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Heating and Air Conditioning

1. SD 7H15 0 24 0 25 York 210 0 30 0 32 Zexel DKS 15BH 0 20 0 21 DKS 15CH 0 20 0 21 Seiko Seiki 121 DS5 0 22 0 23 If you remove any components of the air conditioning system you need to add back the amount of oil usually found in that component using one of the oils shown above Here is a guide e Compressor Same as amount removed from old compressor OR 75cc 2 4 oz minimum e Condensor 22cc 0 7 oz e Evaporator 53cc 1 7 oz e Accumulator Dryer 95cc 3 0 oz e Lines 22cc 0 7 oz file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Mold Odor from A C System Tip from Editor have had a similar problem on both my 1990 745 and 1995 944 mildew like odors from the air conditioning system especially when starting the car again after it has been sitting for some time in the heat and humidity To prevent it limit your use of the recirculation function and turn the a c selector to vent about three blocks before you reach each destination allowing the evaporator to dry out before shutdown Before you proceed try cleaning out the evaporator drain so that debris does not cause the problem to recur You have two effective means of fixing the odor problem once it starts Mild case of mildew evaporator and plenum don t have accumulated leaves etc Buy a spray can of BG Frigi Fresh This
2. Second Comment After posting an e mail question regarding heater blower motors on the Swedishbricks mailing list received a response from Bill Cheb that he rebuilds heater blower motors and adds ball bearings which should add an extra several hundred thousand miles to their endurance Bill was easily accessible via e mail at bill cheb ualberta ca He promptly responded with information on how to order His delivery was prompt and included detailed instructions on how to install the new motor The total cost including delivery was 125 00 960 90 Series Cars found what was supposed to be a replacement at Advance Auto Parts for 29 It was an exact fit mechanically but had the wrong electrical connector returned the motor and ordered one from FCPGroton for 60 which was the same motor with an additional electrical adapter to fit correctly file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Check Rotation at least one case of poor air circulation after installing a replacement blower motor was traced to incorrect motor wiring on the new motor The blower should rotate clockwise and direct air into not from the air plenum toward the evaporator 740 940 Procedure Response Kevin Lawler If you have done several 240 s you should be able to do a 740 blower motor with your eyes closed Remove the under dash hush panel on the passenger side Next remove the r
3. Tip from Gary Hammett My 91 940 turbo had more than 9 screws on the cover All were evident with the exception of one on the upper right side of the drain tube section next to the firewall and buried in the foam padding Most of the screws faced downward but this one faces outward toward the passenger door Because did not see it broke the plastic when pulling the cover down which could have been avoided by first removing the glovebox to see the screw John Martin One screw was hidden on the right corner near the door opening Wires were ziptied to it making it impossible to see Ziptie must be cut wires pushed out of the way then working blind the screw can be removed with an extension and u joint Being extremely patient and flexible is a vital skill Make sure you find all the screws because they are hard to find particularly near the firewall used a combination of sockets 7mm ratchets flexible socket driver and bought a cheap box wrench and bent it into shape to be able to get all the screws out When you have all the screws out gently pry the lower half off This may require a little bit of force because there is very sticky mastic sealing the lower half to the upper It may be a little difficult to tell the difference between mastic and a screw but if you leave a screw in and break the duct you ll have to install some more screws to get a good seal when reinstalling the housing found that had to install some new screws anyway
4. evaporator Place some fiberglass window screen between the cowl and the metal air grill to prevent this You can vacuum up some crud against the evaporator by making a hole in the air plenum and vacuuming with a narrow tube inserted into your shopvac nozzle Seal with aluminum tape See also the tip below on installing an intake filter A parts diagram is shown below 740 940 Procedure Read this entire section before commencing the job The most difficult thing about this job is finding all the screws that need to be removed Plan for a full day Patience is vital because if parts of the evaporator housing are damaged you will have a very difficult time remounting the blower and obtaining a satisfactory seal paid 175 from fcpgroton for a new Blower Motor Resistor evaporator The dealer will charge you about 1000 1200 to replace the evap and recharge the CUMS system Lil 1 Take appropriate safety precautions Consider disconnecting battery for extra safety FBI cae N 2 Get some proper lighting a flood a spot and a little LED gooseneck for those troublesome ras screws at the top of the heater box All lights should be affixed and focused leaving both hands free 3 Properly drain refrigerant 4 Disconnect evaporator to drier receiver connections in engine compartment Be careful to use 2 wrenches to apply the proper amount of counter torque to prevent damage Be sure to have new o rings on hand Tightly plug the drier open connection
5. ie speed greater than 40 mph but when slow down or stop lose cooling believe that am not getting good condensing action even though there is a belt driven fan on the engine suspect that the small electric fan in front of the radiator needs to come on with the A C Response Rob Bareiss Norm Cook If you have one electric fan and no booster as in the 940 cars then it is supposed to be on AT ALL TIMES when the AC is running If you have two fans a belt driven main fan with an electric a c booster fan in front you will find that the booster fan is thermostatically controlled My guess is if you pull your grille out and reach in there to test the booster fan you ll find it does not turn freely So the motor probably burned out when it seized up J ust had three of them do that all on 740 s like yours A good used one can likely be found at a junkyard new one is 211 from Volvo It s probably worthwhile to have your AC system leak checked now as well Simple Leak Detection Mix dishwashing detergent and water in a spray bottle and spray every connection If your system has pressure then soap bubbles will show the leaks Look for an oil stain on the tubing or the connectors since a leak will allow compressor oil to escape the system More accurate leak detection may be made by injecting fluorescent dye into the system no more than 1 4 ounce at a time and no more than twice and using a UV lamp to look for leaks by drawing a vacuum o
6. 36 ounces rather than the 32 ounces called for the A C on the 960 That works for me but remember Tom Irwin recommends a small food scale to put in exactly 32 ounces of R134 If you have to change the condenser found the direct fit aftermarket one from FCPGroton has the advantage over the condenser that was in the car Volvo of no steel plates against the aluminum Otherwise that aftermarket condenser is a bit shorter top to bottom than the one that was in the car with round rather than flat tubing cannot compare capacity BTU between the two condensers but so far that aftermarket unit gives me 32 34 degrees Farenheit air at the vents in the tropics ai ey yh Useful Air Conditioning Parts Products and Tools AScanTech Avantia direct fit aftermarket condenser is 175 from fcpgroton and a Volvo one is 439 from Swedish Engineering A new not remanufactured Sanden SD7H15 compressor is 320 from FCPGroton Locally was quoted 995 yes 995 sight file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning unseen so do not know whether it was new or remanufactured An accumulator will cost you 50 from FCPGroton and maybe a couple of dollars more from Swedish Engineering A Mastercool flush gun is 43 and flushing solvent is 20 a bottle from www ackits com You will need shop air to use those The Airsept kit with Compressor Guard screens t
7. ACC and ECC are similar Tips from Bob have done 2 heater cores on 700 series cars It is very labor intensive You have to take apart the lower half of the dash and partially disassemble the heater case The heater core is on the left lower side of the case You need to remove radio fusebox left side center console panel bracket that holds fusebox bottom left side air distributon box When you can finally see the heater core it looks like a hand grenade went off in your car If you are not familiar with the procedure plan on a weekend You MUST have a good shop manual strongly recommend getting the Volvo OEM climate unit manual see Volvo Technical Literature Repeated Heater Core Failures If your car suffers from heater core failures consider coolant breakdown due to combustion from h ket leaks as one possible source Leaking Hose Connection Masking as Core Leak Jim Parker When replaced the heater hoses gouged the surface of the brass core nipples with a razor knife or screw driver when cutting and prying off old hoses The new hose was pushed up tight against the fire wall that has a opening around the nipple filled with a porous rubber sponge where it leaked pressure tested my core before pulling it and it held pressure So sanded cleaned the nipples and reinstalled hoses which sealed the second time and my leak problem was cured Water Valve Replacement The heater water valve controls the flow of coolant to the hea
8. Diagnosti Vacuum Servos Panel Vent Stops Working Upon Acceleration Replacing Vacuum Servos in ACC Equipped 700 900 Cars Upgrades Homem in Air Filter Diagrams Heater Vents Vacuum Controls and Blower Motor Heater Vacuum Controls Source Leaks Leaking Sound from Heater Controls John Sargent One of my 740s made a hissing sound from under the dash in the area of the heater temperature control lever The manual heater control assembly supplies vacuum to the under hood heater valve to shut off coolant flow to the heater core in the cold position of the control lever The vacuum connection had come off the heater valve and the free flow of air caused the hissing sound at the heater control Connecting the vacuum hose to the heater valve cured the hissing sound and shut off the flow of coolant through the heater core See also the notes below under Vacuum Check Valves See instructions for help on removing the vacuum hoses at the back This rear connection has been known to leak Leaking Sound from Under Dash That vacuum leak is almost certainly your floor defrost diaphragm It is on the left side of case just above the accelerator pedal This diaphragm unit is double acting i e it has vacuum to pull it both ways blue hose for defrost and yellow for floor There is a boot that seals the side that yellow hose applies vacuum to and when this boot goes bad it leaks when you use a c or floor settings It is a HARD job to replace thi
9. If the charge is proper in high temperatures you might never see a time when the compressor clutch cycles off until the cabin is cool or the temperature drops outside If the charge is too low it ll cycle frequently to keep ice away If the charge is too high you will blow the system up That s why you need to know how much refrigerant is in the system In very high ambient temperatures it s occasionally advantageous to have a slightly low charge only because the pressures of the system are maintained at a more optimum level despite the huge outside temperature differential But that same system will be largely ineffective if the temperature is lower The whole picture is you should make sure you have the proper charge as often as possible especially if the system has a leak That way you ll be assured proper cooling good compressor life system integrity and for you sanity Fortunately A C work is NOT very hard if you take the time to read about it a little bit and learn about what causes it to function as it does Why Keep the Correct Charge in the System Motor Magazine Apr 03 A just low R134 refrigerant charge typically a 10 to 20 undercharge significantly reduces oil flow according to Four Seasons Jim Johnson He gave this example for 88 F ambient The a c duct temperature rose just 3 degrees from 46 to 49F hardly enough for a customer complaint Yet so much oil was trapped in the evaporator under low refrigerant conditions
10. OE valve Try a big box auto supply store For Air Conditioned Cars The heater water valve is installed in the engine compartment right near the top of the transmission fill tube and under the intake manifold near the firewall It s hard to see it and the area is crowded best to feel down the bottom heater hose until you find it Be careful around the throttle and kickdown cables so you do not crack the end fittings To replace Disconnect battery ground Pinch off both heater hoses in the engine compartment Remove the vacuum line attached to the valve Remove the valve Clamp screws are 7 mm and you will need an extension and universal joint to access them Install the new valve and tighten the clamps RMagoo The valve goes between the heater hose connected to the short pipe coming out the cylinder head and the heater hose entering the bottom tube of the firewall connector The arrow on the valve points toward the firewall The top heater hose goes to the red pipe behind the head leading to the water pump 5 Install the vacuum line APUNE For Heater Only Cars The heater water valve is installed in the left side footwell up near the left edge of the center console behind the kickpanel It is mounted to a plate on the firewall It is round with a hose entering it from the heater core file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning To remove Discon
11. a 1 4 20 threaded hole in the center of this pattern to push on the shaft end If you have access to a mill of machine shop you can easily make this puller Removing the clutch is pretty easy but removing the bearing and pulley is a pain and requires a more exotic special tool The only reason I ve seen for replacing the clutch alone is due to all of the spring bars being broken For the cost of the clutch alone you are probably better off getting a whole compressor Clutch Sources Tip from Rafael Riverol Clutches alone may be had from www hancockindustries com Most suppliers sell only the complete compressor with a clutch Rebuild or Replace A C Compressor file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Diesel Kiki Models Inquiry My 87 700 has a Diesel Kiki a c compressor that has seized Is it rebuildable by me or smarter to just remove amp replace Are rebuilts available Are they good as new Response Tom Irwin In the years worked in aftermarket probably bought between 50 000 and 100 000 Diesel Kiki s as rebuildable cores What can tell you Well in general they are CHEAPLY built and not very reliable compared to Nippon Denso Panasonic etc Is it rebuildable by me No Are rebuilts available TONS EVERYWHERE Are they good as new Sometimes they are better the aftermarket KNOWS which components fail and endeavor to improve
12. because various parts of the housing broke anyway and plastic doesn t seem to care for having screws removed and reinserted had to oversize some of the screws to get a good bite See Tips below 9 To remove the evaporator see tips below on removing bolts holding the plenum to the firewall Pull out the old evaporator and install the new one Add compressor oil to the new unit in the correct quantity Transfer the filter and rubber seal from the old evaporator to the new This will require cleaning the old filter and gluing on the seal used duct tape to keep the nuts from sliding down the pipes while installing the evaporator Also this will take some trial and error to get the evaporator up into the housing high enough to get the threaded connections at their proper location in the engine compartment 10 Remove all of the old mastic with a flat blade screwdriver and replace with new It s sold as windshield sealant and it comes in 20 rolls at AutoZone bought 3 8 diameter sealant and stretched it until the diameter was appropriate for the A C cover also put a bead of silicone around the drip tube foam where it contacts the firewall Replace the lower duct housing blower electrical connections and trim See Tips below 11 Notes from Adam Randy It is hard to get the lower housing back in place See Tips below The problem is that the back of that lower cover nearest the firewall needs to slip over the evap which has a pipe loop han
13. can see the heater controls The cable on the bottom controls the flapper valve for heat The adjustable part of the cable is at the heater control If you see a larger part of the cable about 3 8 inch and about 2 inches long that is it Turn that larger part of the cable until you can feel the temperature control knob moving off of its left hand stop You are done Heater Core Leaking Inquiry guess that the heater core in my 86 740 Turbo wagon is leaking cause have antifreeze on the front floor Is this as nasty a job as it looks file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Response Try to find out where the coolant is coming from Usually if the core goes bad you get a coolant mist on the windshield with the defrosters on and you can get some coolant drainage from the A C condensate line or onto the carpets As a temporary fix you can add a stop leak additive to the cooling system But plan on a new core soon Editor Note that air conditioned cars do not have hoses or a water valve inside the passenger compartment Cars with heater only have a water valve on the left side of the console against the firewall inside the passenger compartment and this can leak appearing as though the core is leaking Heater Core Replacement See the separate FAQ file which explains the replacement procedure for the Manual Climate Control equipped car
14. control functions Remove both e Remove the climate control vacuum lines block Remove the climate control vacuum lines at the back of the CCU There is a single clear piece of flexible plastic across the hoses to which all vacuum hoses are attached to keep them in order The hoses likely will be of different colors To remove this group of hoses from the back of the CCU gently pry bit by bit at the base of the clear plastic holder until loose e Remove the climate control unit from the car Light Bulb Replacement See the Electrical Instruments sections describing bulb replacement MCC Climate Control A C Malfunctioning Relay Inquiry The 700 900 FAQ shows the relay cluster but there is no AC or ACC relay shown on this panel Where is it Response Check your wiring diagram If a relay is fitted it generally will be located behind the glovebox Removing Vacuum Lines Tip from Bob The individual vacuum hoses at the back of the climate control unit are fused to the plug on the back of the vacuum valve The plug is held on by two spring washers pushed over 2 plastic pins You need to carefully wiggle off the 2 spring washers then the vacuum plug assembly should slip off Note It may not be necessary to remove the plug you can repair the board in situ using an extension cord on your soldering iron Vacuum Leak Notes Tip from Peter If the terminal plug on the vacuum lines leaks air try coating the base of the plastic vacuum pip
15. fail Look For Vacuum Failures Under the Hood First Response First check the black white vacuum check valve mounted at the top edge of the firewall under the hood above the cylinder head This part is very cheap In order to check the valve just remove it and blow into both sides gently If air goes through only one way then you are fine and this isn t the problem If air goes through in both directions then you have a bad check valve If it sticks or malfunctions it causes the a c vent to stop acting on acceleration It can mimic the failed servo problem noted below Tip from Bob Next check the vacuum supply hose under the hood The vacuum hose for the A C heater can be found under the intake near the trans dipstick tube Look for a small 1 8 diameter flexible plastic hose It goes from the firewall near the heater hoses and winds its way to a tee with a vacuum check valve connected to a larger hose ending at the intake It is common for the hose to rub through from chafing on other hoses or wiring harnesses When you find the leak cut the hose and splice with a small piece of rubber vacuum hose Then check the passenger cabin side of the same hose which can be crushed where it exits the firewall or behind the control head where there is a Y fitting in the source vacuum hose Repair it with a piece of the rigid little spray tube that comes on aerosol cans like WD 40 ECC Equipped Cars Bad Underdash Check Valves The small vacuum check valves can f
16. into evaporator chamber to turn into dirt grow mold blow out air vents and block drainage for evaporator condensation To stop this bought a Shop Vac 3 inch Reusable Dry Filters and Mounting Ring Shop Vac P N 901 07 at Pep Boys for about 5 suppose it can be found through www shopvac com too The bag contains three large sheets of filter paper one sturdy plastic ring and one large rubber band took one sheet of paper and cut from the edge one round piece with a radius about two inches larger than the plastic ring or four inch larger diameter Put this round piece of paper over the air intake and pushed the plastic ring down over it narrow end down Perfect fit Of course one has to remove windshield wipers and that plastic drainage channel to get to the air intake will cut the rest of the sheet of paper to fit over air intake inside the car below the glove compartment and behind plastic trim to hold it in place with the large rubber band Two more sheets of filter paper are left over for future changes tried the A C with the blower set at maximum speed and the paper filter looks like it will remain in place and not blow into the squirrel cage For a 740 760 940 think one could use the filter paper with the rubber band that comes in the bag In my 760 have put a flat grease filter with a plastic grid backing from a stove hood wedged between that brace tube and the rubber lip for the air intake and held with a couple of zip ties Wit
17. is an evaporator disinfectant made just for a c systems by BG the same people who make BG44K Contact BG for a local distributor http www bgprod com InterDynamics makes a similar product found in auto parts stores A small can sufficient for many treatments costs approximately 8 Remove the passenger kickpanel under the glovebox and the right side kickpanel covering the computer module You will now be able to see the air plenum and the blower motor Near the blower motor is the blower resistor with wires going into it Using a 1 4 inch drill carefully drill a hole in the side of the plastic plenum about one inch to the bottom left of the resistor and slightly above the bottom sufficient to allow you to maneuver the spray tube of the can so as to spray toward the driver side of the plenum Approximately two inches to the left of the hole is the evaporator core which is around 8 inches wide and 8 inches tall oriented on the long axis of the car If you want to inspect the system remove the glove box and blower resistor Turn on the engine engage the a c system with the blower on 3 Spray a generous dose of FF through the drilled hole all over the evaporator core Turn off the engine and let the treatment dry Cover the hole with duct tape and re assemble the kickwell You will have a disinfectant odor for about a week and the treatment should last a good part of the season The hole will make it easy to reapply the FF next time The whole job sh
18. it does not contact any part of the condenser Leak Points High Pressure Hose Bracket Wear Editor There is on my 95 940 a high pressure a c hose from the compressor to the condenser Under the RF bumper the hose terminates in an aluminum tube before connecting with the condenser This tube is secured to the underbody with a vinyl coated steel clip which in my case rusted and wore through the aluminum tube causing a loss of R134 The hose assembly is expensive so check the bracket and make sure it is not destroying your a c hose tube through corrosion Should I Use a Sealer In a word no There are two types of sealers stop leak for perforation leaks and seal sweller for leaking O rings and O ring type gaskets They re often combined in a single product While the first will seal pinhole corrosion leaks it won t seal anything else and because it works by reacting with moisture it can clog up your system The second can distort o rings Should I Use Teflon Tape on Connections Don t use Teflon tape Refrigerant causes Teflon to soften and fray and little pieces will break off to clog the expansion device The teflon tape will also buffer threaded connections to cause bridging a gap on a o ring fastener and other types of compression seals All sealing is accomplished by the o rings not the threaded connections which are only used to compress the o rings Should I Use a Tracing UV Dye Yes If your system has a leak using a UV dye will allow yo
19. passenger s side of the condenser Note that inadequate flushing and resulting poor lubrication is the biggest reason for the failure of new compressors see the notes below Check and replace the orifice valve in the high pressure line connection on the passenger side not at the evaporator connection Perhaps a variable orifice valve is called for but get 32 34 degrees Farenheit air at the vents with the factory orifice valve Change the accumulator if it has been there for several years or many miles or lines were left open more than ten minutes so air got in Otherwise Volvo says it can be changed every second or third time you open the A C lines Put in at every connection you open brand new R134 O rings yellow not black lubricated with either mineral oil or an application specific silicone based lubricant instead of PAG or POE oils PAG or POE oils should not be used due to their hygroscopic nature that can promote moisture attraction possibly causing o ring deterioration or thread fitting seizure Draw a vacuum of 29 7 inches of mercury for at least an hour Check that the system maintains that vacuum after you turn off the vacuum pump If you use Johnsen s R134 refrigerant in liquid form you turn the can upside down rather than hold it upright like with Dupont Sava R134 preferably with UV dye the vacuum in the system sucks in a can or two right away As soon as you start the engine suction from the compressor will suck a third can That is
20. ratcheting tighteners you can get almost anywhere wrapped around the HVAC box just to the left of the evap and anchored around the pillar between the front and rear doors It doesn t take a lot of force but it helps to have something holding the box away from the firewall You also need to have the box pushed up while being held out so place a small hydraulic bottle jack and a large flat piece of wood under the box about in the same location as the strap Again it s not force that is needed just something that will sit there and patiently hold the box for you To re install the evaporator cover put the rear in place first then swing the front of the cover upwards You ll still have to wrestle with the whole thing to get the drip tube back up into the firewall but it won t be nearly as difficult as trying to put the cover on front end first Gary Hammett When reinstalling the cover make sure you align the passenger side flange at the firewall inside or you never get the cover pushed back There is a flange or rib on that side Rotate the cover into that flange first and then worry about the driver s side The small bulge in the cover for the evaporator pipe at the rear of the cover is just large enough for you to use the sole of your shoe to help push it into place After did that with a bit of working the cover back and forth at the front it popped into place Don t use a rubber mallet to fit the cover or you ll crack it and have to repair it
21. see AirCondition Com Refrigerant Capacities per Volvo T P 8701201 file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Factory Fill Factory Fill R134 Conversion or R134a Refill Model Mears Engine Type Refrigerant grams grams 760 82 87 B28 B280 R12 1200 1100 760 88 90 All R12 1100 900 780 87 All R12 1200 1100 780 88 91 All R12 1100 1100 740 84 90 All R12 1200 1100 740 940 91 An R12 1100 950 960 91 B6304F R12 1250 900 740 940 91 92 B230F R12 1100 950 700 900 91 B204 R12 1000 900 700 900 92 B204 234 Diesel R12 1050 950 700 900 92 Other R12 950 900 Heating and Air Conditioning 900 93 4 cyI R134a 950 950 900 93 6 cyl R134a 950 950 Oil Capacities See the Oil Chart Belt Squeeling After Recharge Symptom After recharging my a c system with R134 my compressor belt squeels and the clutch will only operate when apply direct battery power to it Duane Hoberg You ve overcharged your system The high system pressures caused the compressor to lock up which caused the squeeling since the metal to metal clutch was slipping Place a gauge on the low pressure test port and if above 40psi on the low side R134 bleed some off and get the low side pressure to about
22. somewhere too it IS a turbo engine and see if that actuates the heater valve flappers The actual vacuum switch is pretty reliable but I ve had to replace the climate controller computer on my 87 764T If the vacuum terminal plugs leak see this tip Air Conditioning Failure Note that the ACC system may also suffer from the same PCB solder joint failures as the MCC unit above ACC Climate Control I nstability Inquiry Recently have noticed that my climate control has a new personality in fact several of them Our early Spring days in Charlotte sometimes require heat and sometimes a c My trouble is that the hvac system delivers heat then coolness then nothing then more unpredictability This happens when set to a temp or total heat or total cool What s more the system s ability to select the right venting for defrost heat a c etc has also gone mad Anyone had this problem or recognize the symptoms Response Abe Crombie The manual on this version ECC contains no troubleshooting charts It only has the list of fault codes The fault code list contains no fault tracing either Any fault codes that would impact temp regulation would make the A C button flash on start up and this was not mentioned Does it not provide heat if you go to absolute last stop HOT and cold air if you go to the absolute last stop COLD These end points override the temp sensors The temp knob being set to either full end point should make system default to t
23. that oil circulation dropped from about 10 to 25 by weight to just 2 to 4 That s a prescription for increased compressor wear and therefore short compressor life Other causes of similarly low oil flow he said are internal restrictions typically from contamination which increases rapidly with low refrigerant poor airflow through the condenser and high coolant temperatures Compressor Cycling in Post 92 Models 93 and later models that have R134A refrigerant as factory fill have a compressor high temp shutdown switch at compressor clutch circuit on comp This can make compressor go off for 5 10 minutes if one of two things is happening 1 refrigerant level is getting low The un boiled refrigerant on a full system that returns to compressor will cool it If it s low this doesn t occur and off it goes 2 If it s over 100 F outside the a c shutdown will occur due to compressor getting too hot You can prevent this manually selecting recirc when it s this hot as the re circulated air entering evaporator will allow the return refrigerant back to compressor to cool it down enough to prevent this Don t let it stay on recirc forever as this will lead to a much increased likelihood of a c odors Turn it off recirc at night or when the temp gets back to normal if it ever does in TX Compressor Cycling in 960 Models Inquiry My 960 s a c compressor cuts off during city driving when accelerating When coasting or on the highway just maintaining
24. the low pressure schrader valve Don t do this unless you have a set of manifold gages so you can ascertain high and low side pressures You should also have a digital thermometer to tell the cabin vent temp Figure around 30 40 psi on low side and 150 or so on high side at 2000 rpm 85F system stabilized for 5 10 minutes and inside cabin vent should run about 40 45F at recirc Recharge After R134 Conversion Inquiry Can t just use the 15 recharge kit from Walmart with the hoses and R134 Tips from Chris Herbst George Downs The complete recharge system is the way to go if you want to destroy your A C system Topping off a system that has a leak is totally unscientific and will yield less than optimal performance e DON T try to recharge an empty system without first evacuating completely using a vacuum pump at a minimum vacuum of 29 7 inches of mercury for 45 60 minutes DON T try to charge without keeping track of the high side pressure A cycling compressor clutch is not the definitive factor in determining proper charge Don t overcharge your A C especially an R134a system You must keep track of the weight of the recharge using a scale If you don t know how to recharge a system get someone else who knows how to either do it for you or show you how to do it right Use ester POE oil not PAG for systems converted from R12 to R134 System Pressures For a chart to compare system pressures at ambient conditions using various refrigerants
25. to the solder connections but this is very rare Applications and I nterchangeability Solder board cracks can occur in the MCC ACC and ECC heating ventilation control units and account for many of the system failures in these cars If the heater works and the a c does not take a look at the board file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning 940 Interchangeability The 940 car units with A C Off or Snow Flake A C buttons are virtually the same except for the different button and different color wiring from the panel to the PCB board The positions of the wires in the connectors are the same They are Interchangeable with no modifications Gaining Access to the CCU PC Board Jay Simkin To access the printed circuit board e Gently straighten the four twisted metal tabs which secure the shiny metal inspection plate e Once the tabs are straight lift the plate gently using a small flat blade screwdriver e Remove the four small screws that secure the circuit board Remove the two screws holding the relay connector A magnetic screwdriver keeps you from losing them e Do not touch the ribbon connector the board can stay attached to the rest of the CCU while you repair the printed circuit board You will work on the underside of the board where the mounting pins for the devices at the top of the board stick through the bottom surface of the
26. 0 and wiring harness p n 3522545 7 The new liquid lines vary depending on engine and model check your manual for the part numbers This is a good addition to make if you have to replace a liquid line use the new models and buy the switch and wiring suffered a compressor failure due to just this deficiency In addition if you have to replace a compressor try to get a new one with a blowout valve Condenser Replacement Inquiry How do I replace the condenser after have experienced a large system leak Response Editor To replace the condenser in a 90 e Remove grill top grill cover panel and upper radiator support member e Remove the front air baffle air filter intake and sensor connectors to condenser e Remove bottom air baffle between spoiler and radiator bottom file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning e Disconnect condenser Note this may be a challenge due to rust and corrosion use PBlaster Plug pipes to prevent dirt and moisture from entering system Remove by lifting straight up careful of chrome and once removed measure the oil that drains out the old one if any Remove pressostat sensors Install foam rubber seals on new condenser remove from old and rubber bushings on bottom and or top Clean oxidation from condenser connectors and ensure you will have a good seal Add compressor oil in the correct quantity Reinstall usi
27. 28psi Air Conditioning R134 change from R12 in Volvo cars Basics on Air Conditioning R134 Retrofit Tip from Larry Carley Underhood Service April 1999 In most instances and in most vehicles a basic R134 retrofit procedure is all that s required to retrofit an air conditioning system By basic we mean recovering any residual R 12 that may still be in the system draining out the old mineral oil replacing the accumulator or receiver dryer and then evacuating the system to purge air and moisture adding the specified amount of POE oil for the compressor and recharging the system to 85 to 90 percent of its original capacity with R 134a It s important to remember that R 134a or any other alternative refrigerant cannot be mixed with R 12 or used to top off an R 12 system If an A C system still contains any R 12 at all it must be removed using approved recovery equipment venting is not allowed before a new refrigerant is added to the system This is an absolute must to prevent cross contamination of refrigerants and cooling performance problems R 134a and mineral oil won t mix So if somebody recharges an R 12 system with R 134a and doesn t add a compatible ester POE lubricant the compressor will soon fail Volvo was the first auto maker to approve POE oil P N 1161442 7 for R 134a retrofits Volvo retrofit kits include a new receiver dryer and O rings color coded yellow for the expansion valve and a new expansion valve or orifice tube
28. 5 screws one electrical connector ground lead and there is a motor cooling air tube Motor housing is usually sealed with RTV to prevent any air leaks To get it out remove panel above passenger feet remove the right side hard panel unplug and remove computer and the computer bracket You should now have enough space to get it out 8mm nut driver on flex extension is helpful Remove the tube from the motor housing and inspect the lower bearing any signs of water or rust in there likely means lower bearing is trashed and motor will soon fail Then use air nozzle to blow in to the drain and force any debris leaves out through the blower motor hole or try clearing with piece of coat hanger Just be careful not to damage the A C unit inside Of course the air method may only move the debris away from the drain temporarily Editor s Note Check that the blower motor mount in the air plenum is not cracked Front Footwell Vent Seals See the FAQ section describing leaks at the seals behind the front footwell vent panel covers These can leak and soak the carpets Other Leak Sources See the Body Glass section for other sources of leaks Air Conditioning Air Conditioning System Maintenance Procedure from Rafael Riverol Recharge After Leaks See the FAO Section below for the correct procedure Can I Use Sealer to Fix a Leak Editor In a word no Sealer really does not work long term and instead serves to contaminate your system Many A C t
29. Gunn My 95 960 clutch disintegrated due to heat damage to the bearings The compressor is a Sanden SD7H15 suspect the order of events was 2 out of 3 clutch springs broke clutch started to slip causing great amounts of heat bearing lubricant dried burned plastic bearing cage melted bearings became unevenly distributed around the race clutch contacted windings of coil searched far and wide for a new clutch The only source could find was Volvo over 350 Canadian 225US ended up having the compressor replaced at a non Volvo A C shop They used a different model Sanden compressor but the system seems fine now 3 1 4 20 IIRC screws to pull the pulley don t know what the spec is Gregg Shadduck See http www sanden com index php id MTExOTk30TEwNw 6 for an online service manual Clutch Bearing Replacement Robert Reagan If you have noise coming from the A C compressor bearing you can replace the clutch and or bearing without removing the compressor was hoping to avoid having to open the system to remove the compressor and then having to replace the receiver dryer and recharge the R134a The tricky parts of the job were maneuvering the circlip tool around the shaft of the compressor using a mirror to see to remove the circlip holding the pulley on plus pulling the clutch off the shaft without a proper pulling tool But it can be done A local bearing supply house was able to match the bearing with a duplicate it even had the sa
30. Heating and Air Conditioning Heating and Air Conditioning FAQ Home Volvo Maintenance FAQ for 7xx 9xx 90 Cars Heater Vents Vacuum Controls and Blower Motor Heater Vacuum Controls Source Leaks Heater Problems Heater Core Leaking Water Valve Replacement Vents Blowing Black Foam Specks Blower Motor Failure Blower Motor Replacement Interior Water Leaks Loose Water Shields Clogged Ventilation AC Drains Air Conditioning Air Conditioning System Maintenance Poor A C Performance Diagnosis A C Compressor Cycling or Not Engaging Air Conditioning Leaks A C Recharge Tips A C R134 change from R12 in Volvo cars Variable Orifice Valve Addition R134 versus Refrigerant Alternatives A C Adding High Pressure Cutoff Switch to pre 1992 Cars Condenser Replacement Evaporator Replacement Hose Replacement Receiver Dryer Replacement A C Compressor Failure Compressor Clutch Failure Rebuild or Replace A C Compressor Mold Odor from A C System file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Removing Panel Vents Climate Control Units Access to Climate Control Unit MCC Climate Control A C Malfunctioning A Heater Control Not Workin ACC Climate Control Instability ACC Temperature Sensor Not Operating ECC Climate Unit Not Operating E limate Unit
31. It is suitable to charge into the accumulator as is plainly evidenced by the presence of a charge valve attached to the same low side pipe adjacent to the accumulator Again it is STRONGLY recommended that anyone who is unsure about the components of an A C system avoid work until a time at which they have become sure about it Damage to the system and injury can result Verify all information before attempting any air conditioning repair or maintenance As a review here is a breakdown by model CCOT systems GM type 240 1991 1993 ONLY 740 1988 unable to verify should be all 740 models 760 1988 unable to verify should be all 760 models 940 all 960 all S90 V90 all Recommended System Maintenance When the System is Open As soon as you have warm weather evacuate your A C raise the front of the car remove the air guide not engine pan and front grille Disconnect and mark or identify the three connectors at the bottom of the condenser on the passenger side Unbolt the lines in and out of the condenser Cap or cover with tape those lines to keep air and humidity from entering the system Undo the clamps that hold the radiator in place push the condenser up from its moorings and pull it out from under the car Undo the screws that hold those plates at the bottom of the condenser and put plastic or rubber plates between the steel plates and the condenser to keep metal to metal contact between steel and aluminum Perhaps the plastic like shims th
32. Monty Cracks in the Lower Cover Adam Burke don t know of any way to repair this kind of plastic It doesn t respond to the plastic primers and glues that normally use If you sand it JB Weld epoxy will adhere but JB Weld won t give you the strength the plastic had before it cracked also tried to patch it from both sides with fiberglass but the fiberglass wouldn t stick even to the sanded surface 960 Procedure Editor Your evaporator is far easier to remove than that in a 740 or 940 Remove the battery negative and evacuate the air conditioning system Remove the firewall connections including the metal plate and washer for the pipes leading to the evaporator Remove the glove box and passenger kickpanel then the plastic evaporator cover Pull the evaporator out You may have to remove the air bag bolster the large metal bar near the glove box if it is in the way of the evaporator Hose Replacement Tip from Rafael Riverol When retrofitted my 760T A C from R12 to R134 put in all new Volvo parts from Swedish Engineering including new hoses Soon found the entire hose from the compressor to condenser glowing green with UV dye because R134 was leaking right through the body of the hose Later found out that Volvo has information out recommending use of barrier type hoses when retrofitting A C to R134 It turns out original hoses will hold R134 only when saturated with mineral oil used with R12 New hoses or flushed out old
33. Volvo says the system should be evacuated for at least 50 minutes following recovery of the R 12 and component replacement to pull out as much residual R 12 as possible Volvo also says the shaft seals on Sanden 508 and 510 compressors must be replaced when converting to R 134a The new seal is P N 9134344 2 If the compressor is being replaced it should be filled with POE oil through the fill plug only never through the inlet or outlet ports Also if the compressor is being replaced Volvo says not to add oil to the receiver dryer Editor At conversion consider adding both a variable orifice tube and an in line filter in the compressor suction line both described below to your system to improve low end cooling and protect the compressor against any system debris Procedures How to retrofit R134 into R12 systems Dave Urban developed a series of HTML pages showing the instructions and illustrations for the Volvo retrofit kit for 7xx cars adding Dave s annotated comments from his own changeover These files are duplicated with thanks to Dave here Ulustrated R134 Retrofit Procedures for Volvo Cars by Dave Urban Chris Herbst There is only one way in my mind using the Volvo kit All you have to get on top of the Volvo kit is the two compressor O rings There is no other way there is no acceptable alternative and there is no insta conversion kit that allows you to bypass ANY ONE OF THE STEPS OUTLINED IN DAVE URBAN S DESCRIPTION ABOVE Skipp
34. ail One valve feeds the ECC system and the other feeds the inside temperature sensor in the dome lamp assembly Part number 9134341 8 each costing about 11 All Try Cleaning the Air I ntake Tip from Larry Jacobson Before doing any cutting and sawing your arm up into the air intake that goes up in back of the file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning glove box You may be able to feel bits of plastic or paper or other light foreign matter that has been sucked into the system and is causing the flappers to not close The vacuum motors huff and puff and hiss trying to slam the doors on the accumulated crud I ve had to do this twice and both times found all sorts of stuff up in there My wife has a habit of clipping coupons in the car Bits of paper fall to the footwell and some get sucked into the AC system Makes a racket like baseball cards in the spokes of the old Schwinn bike All Diagnosing the Vacuum Motors Inquiry My heat ac won t come out my vents it will come out the defrost and the floor vents but not my regular vents Response Dick Riess The vacuum motors are located on the drivers side You need to take down the portion under the dash and kick panel against the radio area These are not easily replaced if that is what is wrong but through a shortcut suggested by Tom Irwin and receiving some of my mods have done one on my 91 940SE I
35. and you want to test the compressor directly unplug the connector in the black wire going into the clutch assy If you have an ohm meter there should be a low resistance 3 5 ohms measured at the compressor side of the connector to the compressor body or engine block You should be able to jumper this directly to the pos battery terminal or the B terminal on the back of the alternator and see the clutch activate The engine does not have to be running Because of the low resistance of the clutch coil there s going to be a little bit of a spark Symptom My 86 760T is losing its compressor clutch What does it take to change this clutch Diagnosis First is it really the clutch 1 If the compressor is starting to seize internally that will cause the clutch to slip and burn but the fix is a new compressor 2 Is it the pulley bearing making noise That requires a special tool to hold the front plate while you unscrew the big nut on the input shaft The clutch and pulley then press off You need to remove the freon since you re working at the front seal file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning 3 If the clutch is really worn out get the special tool and press it off However compressor rebuilts are not that expensive and once you re at a u pull it yard the cost of a clutch vs a compressor is about the same So I d say replace compressor either used or rebu
36. arger in surface area and the cooling capacity seems to be better than R12 Just for comparison purposes Our shop gets 187 00 to convert an operating 12 system to 134 on a 7 900 parts and labor 375 00 for a 200 parts and labor recently did the same conversion on my 1989 745GL I m not terribly happy with the performance at idle either After some experimenting ve decided there are a few things that can be done to improve things none of which have implemented yet First thing is to make sure the fan clutch is in good working order Second problem is if your mechanic put in TOO MUCH 134a Problem is that the Volvo conversion kit only includes a low side 134 filler port There s no way to measure the high side using the new SAE 134 fittings Because of this there s no way for the mechanic to know what s enough refrigerant in the system other than looking at the dials at fill time The third thing that needs attention is the all too rudimentary aux cooling fan setup In stock on 7xx cars excl 760 1988 the cooling fan in front of the condenser is triggered by a temp sensor in the radiator That s all well and good but doesn t do squat about the condenser cooling What s needed is the aux fan being ON whenever the compressor is on A simple relay that lets either the engine coolant temp OR the compressor turn on the aux fan would be a good first line of defense This would probably be sufficient for most apps in most parts of the world BUT this w
37. arming it up with a hair dryer will make it nice and sticky then mash the screen into it Consider placing some window screen between the cowl and the metal screen to serve as a prefilter fine mesh Place some pieces on to the screen and squeeze these into the screen so it will not fall down in hot weather Wear gloves or use paint thinner to remove from your skin Consider fastening the vent screen with 8 small black zip ties since the mastic adhesive tends to soften and fail in summer heat The cowl drains to each side where leaves can accumulate and block water flow Clean this out Loose Cowl Air Intake Water Shield Response CW If your water leak is on the right side then the shield over the air intake for the heater fan on the passenger s side could be loose The shield is plastic and is underneath the cowl in front of the windshield If the shield becomes detached from the window edge the water runs right off the windshield and into the intake down onto the blower motor and then on the floor had this problem on both my 745s If this is your problem use the 3M WindowWeld tape noted above on the window edge of the shield to keep the water from getting in Before you install this clean off both surfaces with lacquer thinner Debris in Interior Air Plenum PITA to try to dissassemble the air box but you might try removing the blower motor which may be trashed if the lower bearing has been running in water Blower is held in with 4 or
38. at come with Volvo rear brake pads will do the trick This is a good time to flush that condenser before you put it back in the car While you are under the car you may want to remove the engine pan and take out the A C compressor to flush it and refill it with fresh oil Sanden specifies Sanden SP 20 oil 8 45 ounces but think this is PAG 100 oil perhaps with additives Eight ounces of PAG 100 should do in a pinch to refill the compressor Bryan Warfield CAUTION R12 systems that have been converted to 134a MUST use ONLY ester POE oil PAG oil commonly found in oil charge cans intended for use in systems that were 134a from the beginning will cause major problems if used in converted R12 systems It will attack the O rings seals and possibly even the hoses react with the remaining mineral oil in the system and eventually cause death by black goo Taking the compressor out is not bad if done from under the car If possible put in an Airsept Compressor Guard screen in the suction line at the compressor or depending on the model at the receiver dryer If for any reason you have not adequately flushed the system of 5 debris the screen will catch it before it destroys the compressor sending new debris out both the high and low pressure lines Airsept has illustrated instructions at its website see the photo to the right This device will not fit in a number of Volvo compressors if not install a separate filter in the liquid line on the
39. ated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning WWW BRICKBOARD com the burnt wire was connected marked bypass Multimeter now showed good continuity between the 2 solder points Imagine my surprise when put it all back together the MCC works perfectly Vent Control Selector Fails Prevents A C Operation Tip from Jason R Symptom I ve resoldered the MCC unit and still cannot get 12 volts to the low pressure switch Solution After re soldering and replacing the relay i still had no luck in getting the A C to function by kicking the compressor on checked wiring and everything in between and all was working as it should i have 2 spare MCC units a later one with KA 26 otto i a Snow Flake logo on the A C button and an earlier unit with an A C Off button Both were otherwise 2 gt identical took a good hard look at how this A C button actually functioned noticed it relied on the Vent S Selector knob in the middle of the controller which controls the vents and defrost After turning one of the units to defrost i heard the compressor kick It still would not kick with the A C button so took the complete knob assembly from the other unit which i determined to have a bad electronics board and put it in the one which kicked on when in defrost mode This required unsoldering the 2 black or red wires depending on whether the unit is the Snow Flake or A C Off button and re soldering them to t
40. ave the flow maintained at a steady pressure That s why the pressostat is on the low side of your system It senses when pressures are too low and therefore too cold It stops that to prevent icing The reason for the frequent cycling of the compressor clutch is not dependent on only one factor The clutch on the compressor will cycle when the refrigerant pressure drops to 25 The pressostat causes the clutch to cycle If the pressure is lower than about 20 on the low side I prefer that to 25psi for better cooling with R134 then the evaporator will ice as will the accumulator and its associated tubes Then you ve got no cooling at all and the compressor will shut off The compressor will cycle for the following reasons Ambient temperature low refrigerant pressure low as a result of low ambient temp Ambient temp high cabin temp low evaporator exchanges little cooling because cabin is already cool Ambient temp warm to high fan set on low same reason as 2 Ambient temperature high cabin temperature high system charge low Faulty pressostat switch OBWNF To put it all together the system is cycled to maintain the most useful pressure for commonly encountered temperatures With a FULL charge the system will cycle very frequently in cooler temperatures and sometimes will not have the pressure to EVER come on That is how the CCOT systems work and why they cycle the clutch a lot The thermal expansion valve systems cycle the clutch less
41. board e Find the relay a square box like device towards the edge of the circuit board f find the main electrical connector opposite where the ribbon connector is attached which electrical connector has 12 or 14 pins Re Soldering the Control Unit PC Board Soldering Techniques See the discussion and FAQ section under Circuits and Relays for correct soldering techniques on boards Responses Philip J ames Abercrombie We had intermittant AC problems on our 94 940 turbo that were cured by resoldering bad solder joints on the control board behind the switches As usual you need a magnifying glass to see the bad solder Ours looked OK but had a dark circle around the outside and black marks on the PC board from overheating Re soldered it and saved 300 for a new one there are no service parts for this unit Two key areas should be examined closely the connector joints and the relay black box in center especially the compressor connections The solder cracks at the points where the high current load is passed through the PC board connections Tips Patric Paul The faulty solder spot is in the lower half a little to the left Take your time and you will get it done Don t overheat the circuit board while soldering Response Brian Oliver The A C failure was caused by the solder joint between the AC relay and the CCU controller s circuit board as suggested All this stuff is integral with the CCU control panel in the dash On
42. c Vacuum Servos Panel Vent Stops Working Upon Acceleration General Notes nquiry My friend has a 94 960 and the air stops blowing from the vents while the car is accelerating the a c fan is still spinning but no air is coming out when ever the car reaches a steady speed it starts blowing again The same thing happened to me in an 90 760t and it turned out to be a hole in the vacuum line that goes to the vacuum reservoir However can t locate the reservoir in this car Does anyone have any ideas All General Diagnostics This is usually a result of a vacuum leak whether it be an interior hose or servo motor in the engine compartment or at the vacuum reservoir Find the vacuum line that goes to the vent diaphragm vacuum bellows under the dash behind the steering wheel Uplug it and stick a vacuum gauge into the line using a T The vacuum should read engine vacuum at idle Then accelerate the engine if vacuum drops your vacuum check valve may be bad The vacuum gauge should keep a high vacuum reading when you accelerate If the check valve and tubing under the hood are fine and the vacuum reading still drops you have a leak under the dash most likely one of the 4 bellows The electronic solenoids in ACC ECC equipped cars and the vacuum reservoir appear to be more robust and don t give out that often The rubber caps on the reservoir in older cars located behind the front bumper and rubber tubes under the hood have been known to
43. cause the compressor to run dry and seize Even if a compressor is still turning it may have to be replaced if it s leaking making excessive noise or not working correctly Some compressors are naturally noisier than others but loud knocking noises can sometimes be caused by air in the system the cure here is to vacuum purge the system to remove the unwanted air then to recharge the system with refrigerant Metallic noises and bearing noise are usually signals that the compressor is about to fail A new compressor may be needed if the unit is leaking internally or not producing enough pressure due to bad reed valves worn piston rings or worn or scored cylinders etc A worn compressor or one with internal problems will not be able to develop normal operating pressures with a full charge of refrigerant This kind of problem can be diagnosed with an A C gauge set Poor cooling can also be caused by a lot of things other than a bad compressor so don t replace the compressor until you ve ruled out other possibilities such as a low refrigerant charge too much oil in the system air contamination a clogged condenser plugged orifice tube inoperative electric cooling fan etc Compressor Clutch Failure General Notes by Larry Carley Import Car Magazine May 03 If the compressor isn t turning make sure the magnetic clutch engages when energized Underlying problems here may include a bad relay fuse wiring problem or a defective clutch If the clutc
44. ce you have the panel on your bench or kitchen table in my case remove the black plastic cover to expose the circuit board mounting screws take out the circuit board In the middle of the circuit board there is a black plastic box probably the largest component there This is the main relay which switches the compressor clutch current On the solder trace side of the board you may find barely visible cracks in the solder holding this part s pins to the copper traces Mine was easy to see but do know that they are not always so it was an open circuit at one of the larger legs of the box on the board enlarged the solder pad by scraping off some solder mask to allow greater wetting area which think will help prevent future failures Once you find suspicious solder you need to reflow the metal with a soldering iron until it is smoothe and shiny possibly adding a but more solder while you are at it The small electronics soldering iron may not be powerful enough but be careful you don t over do it if you use the big gun shaped tool Be especially careful that all the new solder you add doesn t form a bridge to the surrounding traces Use a desoldering braid to remove excess solder Reassemble install in car and enjoy These HVAC control panels can be fixed as long as you don t need parts They are at least as repairable as Bosch relays They are sturdily built too except for this one badly designed trace on the circuit board am a physicist by tra
45. compatibility with HNBR seals Poor compatibility Freeze 12 80 R134a and 20 R142b Marginal compatibility FR 12 Frig c 59 R134a 39 R124 2 butane RB 276 Freezone 79 R134 19 R142 2 mineral oil Similar results came from the use of mineral oil instead of ester oil Poor means seal swelling in excess of 40 marginal between 16 and 40 They note HNBR and Nitrile are used predominately in air conditioning systems worldwide and were not generally compatible with the alternate refrigerants Some of the problems reported from material incompatibility include Seals swelling where they would no longer fit into the glands Seals splitting open Seals extruding between metal gland surfaces Seals turning into a gum type material Hoses leaking throughout the length of the hose Hoses collapsing on the suction side due to softening Refrigerant later fractionating and leaving behind debris poor performance and damaged systems Conclusion when you convert your Volvo from R12 use R134 and an ester oil To improve performance consider a variable orifice valve Air Conditioning Adding High Pressure Cutoff Switch to pre 1992 Cars 740 780 and the 1991 940 cars do not have a high pressure cutoff switch to prevent damage if there is overpressure from blockages in the system In the Green Book for HVAC page 334 there is a modification to add just such a switch by replacing a liquid line and adding the switch Volvo p n 3522247
46. d snake a small piece of garden hose taped to my shop vac and suck the stuff out cranked the A C on high recirc and all the stuff just blew out Didn t even get a chance to test the garden hose vac Left the vents out for a couple of more weeks just to make sure there were no late arrivals Armor All d the vents and put them back in No problem since Response Wong closed all the vents except one Put the blower motor on the highest setting Maybe if you turn the heat on it would help even more Then stick a vacuum cleaner up to the vent and suck that crap out Should take a few seconds Use a little pick to help get some of the foam thru the vent slots Move around and do the other vents one at a time Blower Motor Failure Bearings Squeek The usual failure mode is squeeking bearings due to age and wear Blower Motor Only Runs High If the motor runs on only one speed the failure mode is usually the resistance pack mounted in the air plenum Sometimes this occurs in conjunction with a motor failure when an overcurrent in the motor causes the resistors to also fail General Resistor Pack Failure Inquiry Several days ago my blower fan motor stopped working It works on the highest setting which is number 5 but does not work on the lower settings Local dealership diagnosed a failed resistor that they determined was faulty in the motor Response Warren Bain Probably a failed resistor pack Remove the lower panel under the glove box
47. e firewall Another suggestion everytime you get a screw back in take a break You are laying upside down in the car working over your head in the dark very frustrating Tips for Removal of Lower Cover Adam Burke Monty It does not appear possible to remove that lower cover without breaking it unless you first remove the bolts that hold the HVAC plenum in place The evaporator drain extension is in the way Use a 12 or more of 1 4 socket extensions to access those top screws You will need to tape the extensions together tape the socket to the extensions and use tape or putty to keep the screw in the socket If you don t you will suffer With this method and proper lighting the hidden screws aren t that tough When you have removed the screws between top and bottom halves and you are trying to figure out what else is holding the cover it s wedged between that extension and the protruding evap drain To get around this remove the two bolts at the fresh air intake and one on the firewall behind the receiver drier see air plenum diagram below Instead of removing the exterior cowling and rain guard to get at the fresh air intake bolts reach up through the fan shroud from below with a 10mm open box end combo wrench Looking through the hole where the fan motor goes the bolts are on the top of the metal bar facing upwards It s easy enough to do with the right tools and saves a LOT of time The bottom evaporator cover comes out much easier front
48. echs will refuse to use their refrigerant recycling machines on your car if you used sealer Some may install sealer by themselves but they are better qualified to calibrate the injection Far better to identify and replace the leaking component or abandon the A C if you can t afford to repair it Basic A C Operation Information and Safety Caveats Chris Herbst A C does differ between RWD models so it is important to relay the CORRECT information about which side of a particular system the components are on Don t up getting something backwards or reading high pressure on the low pressure side and overcharging and exploding a system And possibly getting hurt in the process For these reasons it is HIGHLY recommended that anyone who is unsure of what kind of system they are working on stops and either figures out what it is or abandons the job until they can figure it out Also it would probably be good for people who are confused about these differences to STOP giving advice before someone destroys their A C or gets injured This is a review of systems on the 740 940 The 940 information applies to certain models as noted in the section labeled 940 Models are listed by vehicle model because most of the confusion have seen is primarily caused by people applying 240 TVX A C information to 940 CCOT A C systems Included at the end of the review is a breakdown by model Information on model years is stipulated when known to be true otherwise model info
49. eeds replacement and your dash gauge is not reading correctly Cheap and easy to put in a new thermostat to confirm e Your heater core has a deposit of sediment or minerals restricting the flow of warm coolant in which case the system may benefit from a backflush e The heater water valve has a blockage restricting flow and may be in need of replacement e You have a vacuum leak which causes the heat vent control to work improperly Your firewall side heater water valve was installed backwards The arrow on the valve points to towards the firewall inlet not back towards the engine Control cables from the heater control unit to air mixing doors are maladjusted or broken In heater only cars no AC unit the water valve which is inside the cabin above the left footwell is controlled by a cable from the air mixing door e Pete Fluitman Check the heater hoses have seen several 700 s where they are swapped over and it results in ZERO heat See the section on Water Valve Replacement for correct installation instructions Heater Won t Completely Shut Off Hot Air Tip from John Sargent 700 series with manual temperature selection have a reputation for not being able to completely shut off all of the warm air when the manual temperature selector is fully off The problem is the flapper door in the heater is not fully closed There is an adjustment for this in the cable just behind the heater control If you remove the glove compartment you
50. emoving it Noel DeSouza On my 85 740 you press in and then pull out from the side to retract the hinge stub Editor Insert a small flat screwdriver between the surrounding plastic trim and the side of the moving vent opposite the air flow selector wheel Carefully lever the vent out Climate Control Units Access to Climate Control Unit Removing the CCU Unit Jay Simkin To remove the CCU control unit e Disconnect battery ground to prevent shorts e Remove storage tray lighter unit removal bezel around lighter lifts off with fingers grip on the edge at the passenger side of the bezel and pull gently file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning two Philips head screws and three electrical connectors to the lighter Using a blunt edge putty knife press the edges of the console outwards so that one side of the storage tray can be pulled out Then the other side will come free easily This is easier than trying to pull the storage tray straight out e Remove the black plastic faceplate around the climate control unit It is fragile so be GENTLE Start at the section around the climate control unit Using your fingernails or better a plastic knife gently lift to disengage the thin plastic rim from the lugs that secure it It will come free with little effort To free the center part of the faceplate from the clip that secures it use a 1 w
51. end firewall end first It s counter intuitive but there is more room to pull the drip tube clear of the firewall drain hole this way The wrong way If you pull the back of the box down first the front part pivots against the bottom of the evaporator and pushes the drip tube forward against the firewall not what you want Worse this puts a load on the drip tube area of the box and it s likely to break at this point You can t see what s going on while the lid is in place so you can t actually see the cover wedging against the evaporator Tips for Installation of Lower Cover But if you ve loosened the bolts and air intake mount that anchor the HVAC box it probably will have dropped some If it has dropped even 1 4 the lower cover won t fit at all It will run into the firewall before the screw holes line up If had to do this again would first see if it would help to have an assistant push up on the evaporator while remove and later replace the lower cover although this will be difficult because you both need to be in the same place at the same time If that wouldn t work then would remove the HVAC box mounts and pull the whole thing away from the firewall as much as it could go before would work on the lower cover A wedge such as a rag stuffed behind the box might help hold it out temporarily but frankly it didn t work for me When reinstalling if you don t have a helper use a ratcheting strap those flat nylon straps with
52. es a reading that is within 50F to 180F If it says it is 60 deg out when it is 96 the control unit doesn t know it is a bad reading Location of Ambient Temperature Sensor Steve Oakes Remove your glovebox and lower plastic shroud under the glove compartment The sensor is mounted on the air plenum it has wires running to it and removes by twisting 90 degrees ACC ECC Interior Cabin Sensor Tip from Mike Sullivan Just a heads up for those of you with ACC systems My 93 960 had been holding cabin temperatures lower than the level set on the dial at least for heat where 72 was more like 66 68 over 3 E the last year or so For a while I thought this was going to be a problem with the dash computer or some other complex piece of the automatic system Some had suggested that it was likely to be the sun sensor located on the top right of dash at the speaker On studying the system more settled on the most likely problem as being the temp sensor located in the overhead dome light fitting where there is a little hole and air is sucked in past an electric sensor Note that there were no fault codes showing Just before ordered a new sensor found the answer dirt collected in that tube in the dome light leading to the sensor The fix turned out to be a couple of squirts of an electrical contact cleaner into the small hole where air is drawn into the temp sensor in the dome light The excess runs out and in my case brought out a bunch of b
53. es with silicone sealant You have to coat around the base of each pipe Be careful not to put any near the top so that it doesn t plug up the openings in the pipes Diagnosis Notes Response Patrick Paul First check whether you have 12V at the low pressure switch on the receiver dryer if so then all components before that are OK as far as turning the voltage off and on Then test the electrical connector on the compressor and check if you have power there If yes then your problem is the control unit Any loose solder on the control board lets just enough current flow for you to get a positive voltage reading But the amps are not enough to turn the compressor on The repair is very easy once you find that spot in your control unit circuit board see red circle in photo to the left Response Abe Crombie The control panel with the knobs is the control unit The electronics are part of the control The a c compressor relay on the 91 95 740 940 with the manual a c system is integral with the control assembly The relay usually isn t the problem it is the solder joints from the connector to PC board or PC board to relay pins The relay is soldered to the circuit board When you remove the control panel you will see the metal enclosure for PC board Response James Abercrombie The time delay for compressor start is integral in the electronics of this board so there can be a failure of the circuit that stops the a c compressor that is not related
54. g the recirculation switch pressed in and the A C switch released out Shine a strong light on the solar sensor in the dash speaker otherwise the DTC for the sensor will be displayed even if fault free Retrieve the DTCs by pressing the A C button in and releasing it within 5 seconds If several DTCs are stored they file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning will be displayed sequentially All will be erased when the ignition is turned off If no faults are set then 1 1 1 will be displayed Note that faults may be in the component or in its wiring To diagnose cars with ECC but without air conditioning no trouble light will illlumine the system will fail Remove the ECC module from the dash panel take off the cover plate and press the diagnostic test button twice within 5 seconds Read the DTCs from the nearby LED lamp pressing the button after each DTC to read any more codes Table of ECC Diagnostic Trouble Codes Fault Classes A Serious M Minor No warning to driver DTC Fault Component amp Description Fault Class 1 1 1 Fault free Ambient temperature sensor on blower housing 1 2 1 Short circuit to ground 1 2 2 Open circuit or short circuit to 12V Interior temperature sensor in roof light 1 3 1 Short circuit to ground 1 3 2 Open circuit or short circuit t
55. ging at the lowest point That pipe loop hangs right where the firewall takes a bend towards the cabin and the proximity of that pipe and the incline of the firewall makes it nearly impossible to sneak the cover between there without breaking the plastic One thing that helps is to reach back with one hand and press the evaporator away from the firewall a bit since the housing catches on the tube on the bottom of the evaporator also cut the drain foam plug in two on the bottom and resealed it with RTV which gives you a little more room See the Tips below 12 Reinstall evaporator cover screws The screws are easy to strip from too much torque It s best to watch the box while you re turning the screw Stop turning when the cover contacts the box as opposed to turning until the screw feels tight 13 Reconnect evaporator drier receiver connections in engine compartment Again be careful to use 2 wrenches to apply the proper amount of counter torque to prevent damage recommend using new o rings 14 Evacuate and refill with refrigerant and makeup oil 15 Reconnect the battery 16 Enjoy cool air Tips For Removing and Installing the Evaporator and Plenum Cover Jan Kinner Taking an evaporator out of a Volvo 940 is not an easy job There is ZERO clearance to get to some of the screws that need to be removed see illustration of MCC plenum unit in right side footwell above And even when all the bolts were taken off still broke the evap
56. h fails to cycle on and off when the A C is turned on jumping the clutch lead with a jumper wire from the battery will show if the problem is in the clutch or elsewhere If the clutch engages the problem is the clutch power supply relay fuse wiring switch or control module Refer to a wiring diagram and work backward toward the battery to find out why the voltage isn t getting through Many A C systems have a low pressure cutout switch that prevents the compressor clutch from engaging if system pressure the refrigerant charge is too low This is designed to protect the compressor from damage in the event of a leak So if the clutch isn t engaging check the refrigerant charge and the cutout switch Diagnostic Notes Diagnostics Where can hook up a jumper wire to see if the AC compressor clutch is still good Herb Goltz In 740 cars remove the connector at the low pressure switch on the accumulator dryer the aluminum cylinder at the firewall Jumper across the two terminals inside the connector a paperclip works fine With the AC set to on and the engine running the compressor should engage IF the terminal inside the connector is receiving 12V power via the 10 second delay relay behind the glove box In 940 cars remove the same low pressure switch connector at the receiver dryer and jumper it current comes directly from terminal 10 of the MCC control unit with no relay Larry Spooner If there is a circuit problem after the above test
57. h the plastic grid facing down the filtering element is kept from being sucked into the squirrel cage Dick Riess This idea works for 960 cars it would also work on the 940 SE as it is basically a 960 body The air intake is similar Diagrams Selected parts and assembly diagrams for the HVAC system are shown below CU MCC climate unit main components exploded view Coie CAC file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning SSB 337 azas tay sete Os ee file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning CU MCC Air Plenum Diagram file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Volvo Maintenance FAQ for 7xx 9xx 90 Cars file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM
58. he other board installed the unit once more and it worked When all else fails it could simply be the Vent Control selector that is preventing the A C button to function ACC Heater Control Not Working Inquiry Re 1987 765T while at the dealer getting a new transmission put in also had them install a new heater control valve The automatic climate control system will not put out any heat at any setting even with defroster on The dealer believes the problem is a vacuum connection in dash The heater control valve is not getting vacuum Previously pulled the glove box out and checked the vacuum hose and shutter doors there they seem fine The A C works fine Dealer says it is about an hour s labor to look in the center dash to find the vacuum problem Can do this myself Response Several things could have happened most likely because the dealer who put in the new trans broke a vacuum line or crimped one somewhere if you had heat before the trans was put in There s a plastic vacuum reservoir underneath the car passenger side up front near the radiator and should have a hose line leading to the engine and one leading to passenger compartment Check for vacuum at the engine line and at the line leading to the passenger compartment and the ACC control unit usually through a T connector Fix as necessary You might try putting straight engine vacuum or vacuum pump to line going to passenger compartment there are check valves
59. he respective mode If this isn t happening then the servo that moves temp file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning door needs inspection If the temp goes to the proper mode at end points but not in any other temp setting normal operation as opposed to end point defaults ACC Temperature Sensor Not Operating Blower Motor Ambient Temperature Sensor Inquiry When its cold out usually around 50 degrees the air conditioning works OK When its warm out it doesn t work at all No fan No a c assume its one of the sensors probably the one on the dash Its a 3 wire affair with a small lens in front The other one is in the ceiling light but don t think that s the one giving me a problem Any suggestions Response Abe Crombie The solar sensor is not going to cause anything to fail to function on that system It only makes the system go slightly colder when it s sunny It sends no signal anytime it s dark outside The sensor next to blower motor may be at fault Turn the air distribution knob to face vent the temp to full cold fan in AUT a c switch off and recirc on Now punch the a c switch on and then off and count the flash code punch a c switch again and repeat reading two more times This will give any fault codes that are present in system The sensor can be bad and give no code as the system doesn t know it is defective as long as it giv
60. hoses cleaned of mineral oil will not hold R134 because its molecules are smaller than those of R12 had received and put in the car an original Volvo hose good only for R12 Be sure to put in new barrier type hoses designed to hold R134 when retrofiting from R12 Rebuilding Hoses ve found that flexible ac lines typically start leaking at around 100k miles and can be expensive to replace I ve located a repair service in Tucson that can fix your existing line for around 50 mail them the old hose and they rebuild it They seem to do good work Century Auto Air Jim McDonald Hydraulic hose shops with Parker capability will be able to rebuild the hoses and fittings Anecdotes on Brickboard note that Volvo OEM availability of such parts for 740 940 cars is diminishing so we may be doing a lot more rebuilding of failed hoses and parts Poor Quality Control in New Hoses John Orrell received a wonderful looking Volvo sourced AC hose from FCP Groton this week file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning It was in a sealed bag Volvo labels all over it made in Poland It even had soft rubber covers over both ends of the hose fittings But when removed the rubber covers saw a rather large quantity of metal shavings inside the hose pipe ends from where they cut the ends to size There were enough shavings that it could have done damage to the compressor so if
61. ide flexible putty knife with the edges blunted use sandpaper to do this You need to raise the center section of the faceplate that is between the climate control unit and the switches which are to the right of the ignition There is a metal clip behind the middle of this center section to the right of the switches Insert the putty knife edge at the bottom of the center section With the putty knife at 45 degree angle to the face of the console insert the edge of the blade into the opening at the bottom edge of the faceplate s center section Push the knife handle downwards gently levering outward on the plastic faceplate Do the same at the switches which have plastic clips holding them When the clip pops free move towards the driver s door US Canada models the end of the faceplate that goes around the climate control unit This disengages the end of the faceplate around the ignition switch from the two lugs which secure it e Remove the radio e Remove the radio housing two T 20 screws in the roof by gently pulling the console sides outwards and pulling on the bracket e Loosen the steel radio housing support bracket 4 hex head machine screws 10mm two on either side of the bracket Remove the four philips head screws in the front of the climate control unit and gently pull the unit forward until you can access the back of the unit e The CCU should have two electrical connectors one for the fan selector switch and the other for the
62. ight side kick panel over the fuel ecu then remove the 2 screws holding the ecu and remove the ecu next remove the 3 screws holding the ECU bracket and remove the bracket Now remove the 3 or 5 screws holding the blower motor in place and remove the blower motor Remove the ground wire from the old motor if so equipped and unplug the power wire or the connector Install new motor in reverse order Some cutting and modification may be required depending on the style of the motor had to rewire the connector with a soldering iron but that was no big deal have done several of these always in less than 1 Hr Response Ney The only important tip is to remember to disconnect the battery because the ECU may need to be removed in order to gain access to the blower Also remember the small black wire with self tapping screw is ground on the single connector motors Newer motors are dual prong Karl Siegler Make sure any dirt and dust caked on the fan is removed as even a little build up will cause the fan to be out of balance and thus reduce the life of the blower motor Some soaking in hot soapy water and an old tooth brush completed the job be careful not to disturb the balance clips 740 Modified Motor Mount Response Gary Defrancesco In the last 6 months have replaced the blower motors in both of my late 80s vintage 745Ts The replacement kits came from IPD and include the adaptor ring required to mount the new blower to the heater AC bo
63. ill also mean that the aux fan comes on when the system is put into DEFROST mode as the A C is always on then to dry the air If you re like me you don t want that to happen when it s really cold outside So that would require the addition of a temp cut out switch to the above mentioned two input relay In addition having the aux fan on at highway speed actually will DECREASE cooling performance because the fan is basically in the way So add a speed sensor cut out to the above circuitry Now you ve basically got most of what the more modern 9x0 1993 cars have as standard As a first test for you skip all of this and try wiring things up so that the aux cooling fan comes on whenever the compressor comes on You can fake this by connecting the two wires at the temp sensor up at the top right corner of the radiator effectively bypassing the temp switch itself Use a paper clip or something wrap it with tape close the hood and drive around and see if this makes any difference If this doesn t help I m out of ideas If it does help somewhat you ll obviously need some temp gauges to measure all this there s always the option of grafting the 780 aux cooling fan onto your 740 Volvo has a kit for this which imagine is pretty pricey since it includes a brand new fan etc but they needed it for markets such as Arizona even BEFORE going to 134a As far as remember the kit doesn t include any of the logic suggested above so I m not sure it ll do anyth
64. ilt Apparent Clutch Failure Caused by HVAC Control Unit Jim Holst My 93 945 AC compressor would not come on but measured nearly 12 v from compressor lead to ground was puzzled that the compressor was not engaging Eventually pulled the control unit out of the dash and inspected the printed circuit As noted below the solder connections at the small black relay box were cracked resoldered the relay connections and the AC now works fine What was happening was this the cracked solder joint made a high resistance connection This allowed enough current to flow to let the voltmeter read nearly full battery voltage When the compressor tried to run the high resistance cracked solder joint would not let enough current through to energize the compressor clutch If you Know Ohm s Law think of a series circuit with the 3 4 ohm clutch in series with something like a resistance at the crack of 100Kohm A 10 megohm input meter would read nearly the full supply voltage but not nearly enough current would flow to operate the clutch There is a way to test this without pulling the control unit If you connect your voltmeter to the compressor connection from the rear of the connector without disconnecting the compressor you can measure the voltage when the compressor tries to engage If the solder connection is cracked the voltage will drop to nearly zero With the connector open the voltage will be nearly 12v 960 Sanden Clutch Failure Tip from Ross
65. inch out it came easily Then remove circlips snap rings to get the bearing and coil off There are also some shims that adjust the clutch gap it is important to get these right on reassembly Tip from David Steffy If you don t want to open the A C system you can replace just the clutch amp bearing ass y It s possible to get just the bearing but not to replace it in the clutch Got mine at the local import auto parts store for 125 You ll need a puller tool to get the clutch off The K D one for GMs works and can be borrowed or rented at some auto parts stores Note this is not an ordinary 3 arm type puller Otherwise the swap is straightforward and leaves you with a new clutch plate as well Another Response There is a special tool naturally but it just pushes it off by attaching to the threaded fitting in the hub of the face of the clutch Once that is off there is a snap ring at the front which holds the pulley and bearing on Tapping on the pulley will slowly move the assembly off the front of the compressor Then there are 3 Phillips head screws which hold the coil on to the front of the compressor These round off easily so try tapping on them with a 3 8 2 phillips bit before trying to turn them David Aidnik The clutch removal on the sanden sd7 compressor is not very hard but you must have or make a puller The clutch has a trigonal pattern of 1 4 20 threaded holes and your puller has to have this pattern of 1 4 thru holes as well as
66. ing all or some of the above steps will result in a less than optimal conversion that may cause poor performance system damage or lack of proper function Flushing Debris Out of System Larry Carley Underhood Servide April 1999 ed When a compressor fails it can throw metallic debris into the system Most of the junk ends up in the bottom of the condenser but some of it can also be blown back into the suction hose Flushing the condenser hoses and evaporator with refrigerant or an approved solvent may remove most of the debris One aftermarket supplier s A C flush solvent Dura 141 has seen successful acceptance by the repair industry It has a boiling point below 90 degrees Fahrenheit so leaving residual solvent doesn t appear to be a problem However modern parallel flow flat tube condensers cannot be flushed effectively because debris jams in the narrow tubes Replacement is often recommended if debris is found in the system Most experts also recommend installing an in line filter high side and or low side to protect the replacement compressor and orifice tube or expansion valve Editor Highly recommended filter screens that can be installed in the suction line to prevent any debris from reentering the compressor see AirSept Inc file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning for such a product Some Volvos may need to have this screen instal
67. ing unless some sort of A C triggering is added as well Editor See Recharge Tips above Variable Orifice Valve Addition Lee Fox wish had heard about the variable orifice valve tubes before converted It sounds like a good idea You can find out about them at http www aircondition com vov This is also a great site to learn all about automotive air conditioning You can even take the test online to become EPA certified to buy R12 In summary would recommend the conversion to anyone who needs to fix an ailing AC We be chillin Chris Herbst I ve used several VOVs and they are worth the money the time and opening the system to put them in The VOV does not make a great difference on the highway but in the city under high transfer load it does fantastic work Sometimes it can lower vent temps five degrees plus R134 is not the best refrigerant the VOV makes the best use out of it Also believe that pressure wise it s better for the compressor since there is better oil transfer and the compressor system doesn t get backed up too much heat to effectively transfer out between entering the condenser and exiting the condenser Opening the A C system is not a problem In fact it won t hurt to purge the system add a little oil recharge and replace any or ALL available O rings while you re at it and enjoy better cooling especially in the worst conditions If you are in a very hot climate like Arizona or other areas where temps a
68. ining but years of working in failure analysis in the telecommunications industry tells me that the solder joint in question is under engineered Replacement Relay Randy Duke If the solder joints are fine and the relay is malfunctioning replace it with a Z2570 ND costing about 1 50 plus 2 S H via USPS first class mail from digikey com The old relay is 9V and has a 190 ohm coil resistance with a current load to the A C clutch of about 4 amps though the contacts The replacement relay has a coil resistance of 225 ohms so slightly less current is needed to activate it The contacts are rated at 10 amps Temperature Control Selector Not Operating Tip from Allan Hewick Problem temperature selector knob inoperative Knob controls the distribution shutter servo motor behind the glove box looked all around the board with a magnifying glass and then found the very small section of burnt out broken wire circled in red in the image to the right Burnt broken section of circuit board in red box goes from MCC pin 1 solder connection to another solder connection for a resistor or something and then into the maze of connection within the circuit board In the green wiring book pin 1 appears to have no direct connection to the servo motor control the shutter for air temp but it ultimately connects to ground Solution took a single copper filament from a wire and soldered it at each end where file C Users Steve Documents Volvo 20FAQ 20Upd
69. is a Siemens made replacement blower for a 1984 Chev Citation with the single power connection for use with air conditioning Siemens part number is PM 105 Also look for an 81 Olds Delta 88 w air conditioning blower motor Pre 90 760 Cars The replacement for the 760 series fan motor is a standard GM fan motor at NAPA the part number is 455 1076 was shopping for a fan motor for a 87 760 The clerk responded 57 94 and we ll have to order it Then said ok Try a 83 Chevy Impala with AC In stock and 17 99 with lifetime warranty In all cases you will have to reuse the blower cage Post 1990 740 940 Cars A Factory Air 35339 that lists for 49 88 on the PartsAmerica website will fit with a different wiring pigtail made using an adaptor pigtail from a bit of heavy automotive wire and some female and male crimp on spade connectors This will allow you to connect the original harness plug to the motor without hacking anything Make sure the polarity is correct on installation so it does not run backwards This is the same blower as used in any 91 96 rear wheel drive full size General Motors car Note that post 1990 cars use a different plastic mounting plate The reason the original fan failed became quite apparent in today s rain Water showed up around the new fan Apparently the 740 has a tendency to leak on the passenger s side with the water ending up in the plastic basin that the fan sets in Note See Volvo TSB for a fix for this problem
70. ks Tip from Rafael Riverol Markku from Finland reported epidemic corrosion of the A C evaporator on 93 95 cars due to lower corner attachments with steel bolts in direct contact with aluminum As he reports it iron in contact with aluminum in the presence of water and road salt corrodes the evaporators in four to six years If your 960 is like mine then the A C condenser is held by bolted through steel plates touching the aluminum of the condenser which will corrode and leak refrigerant and PAG oil This can ruin your compressor too and send debris through components and lines that will prove difficult or impossible to flush successfully before putting in a new compressor and condenser BTW To save all the trouble and expense of an A C overhaul after your condenser corrodes and leaks see if it is held by bolted through steel plates at the bottom both right and left sides On the condenser in the 960 it is easy to take out the steel bolts and plates to replace them with aluminum plastic or stainless steel bolts and nuts with plastic or aluminum shims between the steel plates and aluminum of the condenser body That can be done by taking the condenser out of the car from below or taking the radiator out of the car and working on the untouched condenser in place Editor There is a diagonal bracket in front of the condensor in many cars If this is struck or bends it can contact the condenser tubes and cause a leak through vibration and corrosion Make sure
71. lack dirt dust that was insulating the sensor ECC Climate Unit Not Operating The ECC climate control unit in 960 90 cars can suffer from the same solder board cracks as the MCC unit above Symptoms included irregular compressor operation In addition the solenoid valve controller mounted under the dash in the passenger footwell just after the evaporator can also have these cracks Symptoms include both irregular compressor operation and vent doors closing at random not correlated with acceleration The solution is to remove the units and resolder the boards The former is in the upper dash above the radio and the latter is identified by seven or eight vacuum lines and an electrical connector If you cannot control temperatures check your dome lamp sensor unit shown directly above for dust and dirt ECC Climate Unit Diagnostic Codes The ECC climate unit in air conditioning equipped cars can detect certain system faults and display the appropriate diagnostic trouble code by flashing the lamp in the A C button If the control module detects one or more faults the driver is warned by the flashing A C button If a fault is major the lamp will flash continuously while the engine is running if minor the lamp will flash for 20 seconds after the engine is started To read the diagnostic trouble codes the engine must be running the blower selector in AUTO setting the function selector in VENT setting the temperature switch set to maximum coolin
72. led at the receiver dryer because it will not fit in the fitting at the compressor Many compressor suppliers now require this to maintain warranties and avoid unwarranted comebacks If You Replace Any Hoses Make sure you replace with R134 compatible barrier type hoses Lack of Adequate Cooling After Retrofit Diagnosis would have to say that the person responsible for updating this particular 7xx system missed something have performed probably 25 of these conversions on 200 and 7 900 vehicles using the OEM kits provided by Volvo and all of them have worked as well or better than the R12 The secret is to use the proper amount of 134 if you overcharge or undercharge the cooling output is diminished In our shop we use the Snap On charge station that charges the system by dialing in the amount digitally and forces it in by the kg or ounce The only way to get the proper charge is to weigh the refrigerant before installation no way you can guess and be accurate The lack of cooling at idle could be from over undercharged Partially blocked condenser radiator bugs dirt noperative clutch fan or auxiliary fan Too much oil in the system wrong orifice tube should be changed to a tan one weak ac compressor blocked accumulator or ac cycle switch set too high The 200 s are a different story but have never had a complaint for insufficient cooling here in Georgia even from a 245 owner The new evaporator that comes in the Volvo kit is about 30 l
73. ling that your best bet is probably an OEM replacement Dave Stevens If you have a turbo that hiss is from the pneumatic vacuum reservoir for the dash heater amp A C air distribution system Your turbo uses a vacuum pump rather than manifold vacuum to evacuate this container which is why your symptoms are noticeable under acceleration rather than deceleration as you d expect with an NA engine Normally there is a slight hiss whenever you change the heater control positions In your case it seems there is a more noticeable sound and it s hissing under other conditions Although haven t had this particular problem understand it s often caused by a leak inside the heater control unit itself You can replace it or just live with it It could be a leaking diaphragm in one of the air diverter servo motors but that normally just causes loss of functionality rather than hissing Could also be a loose hose at one of the servos but these are fastened pretty good doubt you d find a split hose anywhere Tip Chris de Courcy Bower If the air conditioning misbehaves and hisses when accelerating check the two one way valves that connect the climate control system vacuum pipes to the inlet manifold If they let ANY air through in the from manifold direction when you gently blow into them then replace them The good news is they are cheap John Sargent The two black and white check valves are shown in the picture to the right The car is a 1988 760T but m
74. me number stamped on it pressed the bearing into the clutch with the help of a little oil on the outer bearing surface Put the clutch back on the compressor installed the circlips and nut and was off to the races Engine is much quieter now that there is no bearing noise and don t have to worry about a seized bearing interrupting any trips The entire repair cost 20 Genaro Lopez Sorry to rain on your parade but I ve never had good luck with either replacing the bearing or the clutch on A C compressors And have done many here in Deep South Texas I ve gone to just getting a rebuilt unit That way only have to do it once Pulling the clutch will require you to use a pair of bolts to screw in and they put pressure on the compressor and push the clutch out do not know if you will have room in front of the compressor installed in the engine bay to do this guess you will have to remove the radiator etc to make enough room but it seems to me that you will end up frustrated and unsuccessful Ask me how know still think your best bet is to get a re manufactured compressor Clutch Removal Tips from Loren Rux Ross Gunn Remove the radiator for better access There are three threaded holes for 5mm bolts in the clutch plate and just assumed they were for removing the clutch plate by evenly screwing in three bolts forcing the plate off the shaft Whether or not that is the purpose of the threaded holes it worked After the plate was about
75. n prevent the circulation of oil in the system starving the compressor for lubrication If the condenser is dirty why not just replace it That s what many experts recommend But condensers are expensive to replace The alternative is to clean the condenser with an approved flushing chemical that hopefully will remove most or all of the contaminants Flushing can save a customer a lot of money but it also increases the risk of a repeat compressor failure or an orifice tube or expansion valve blockage if the flush fails to remove all of the gunk from the condenser To reduce the risk of residual debris from a flushed condenser passing into the system and causing problems an in line filter should be installed in the liquid line after the condenser to trap any debris before it can cause trouble A filter screen also should be installed in the suction hose at the compressor inlet to trap any junk before it can enter the compressor Debris can be blown backward into the suction hose and evaporator by a compressor failure too so don t overlook this part of the system if you re flushing to get rid of contaminants 960 Condenser Leaks See the discussion on steel bolt on aluminum tube leaks Evaporator Replacement s 3 j i Evaporator Seals Preventive Maintenance Editor Leaves and small crud are often sucked up into the air plenum a 71 a through Firewall from under the cowl screen They end up against the evaporator where they corrode the expensive
76. n the entire system and looking for loss of vacuum or by using an a c Sniffer designed to detect the presence of refrigerants If you inject a dye into an R134a system make sure it meets the SAE J2297 standard for refrigerant and oil compatibility One dose of dye is enough Adding extra shots of dye not only won t help but because dye changes the viscosity of the oil excessive use can adversely affect compressor life Control Unit PCB Solder Cracks See the FAQ section describing common electrical failures in the heating air conditioning system control units These can be intermittent sometimes the a c works fine other times not Your low pressure switch can fail as well If it does the system will assume it has a low coolant charge and shut the compressor off See the section below A C Compressor Cycling or Not Engaging Inquiry Is it normal for the compressor to cycle on and off like this The one on my wife s old Mitsubishi cycles on and off but it runs for a longer period of file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning time than this one Response Chris Herbst The clutch cycling orifice tube CCOT A C systems such as the one in your Volvo are designed to cycle the compressor on and off to maintain a workable system pressure While the thermal expansion valve systems in other cars vary other factors the FOT fixed orifice tube needs to h
77. nd back on close around 40 psi The bad ones got would switch open at around 20 psi then almost immediately close again This caused the compressor to cycle faster that you could count Trying to figure it out drove me nuts Editor The location of the switch 2 in the photo above on the receiver dryer 1 makes it subject to damage when replacing distributor caps etc Unexplained compressor cycling when you know the system is charged should lead you to suspect a faulty low pressure switch Air Conditioning Leaks Tips from Chris Herbst Paul Willems The common freon leak spots are the condenser any O ring suction line the schroeder fill valve evaporator and the high pressure pipe along the right side frame rail The last one is the most common because the rubber from the straps that hold it down deteriorates from engine heat leaving a lovely condition for bimetallic corrosion Some cars suffer from low pressure aluminum pipe leaks in the pipe beginning at the accumulator that dips down running along the passengers side before turning 90 and crossing above the splash pan where it becomes a rubber hose below the front of the engine again becoming an aluminum pipe where it connects to the compressor The intake pre heat shield or air intake tube rubs against the aluminum low pressure hose causing it to break through If your schroeder fill valve is leaking it is replaceable separately from the pipe Leak Points 960 Condenser Lea
78. nect battery ground and remove left side dash under panel and air hose Remove the accelerator pedal and the the ignition control box and if you have it the cruise control connector all for better access Clamp off lower hose from valve to heater core Clamp off lower hose in engine compartment then disconnect Place cloth on carpet to soak up spilled coolant Remove lower hose inside car connected to valve Remove control housing from water valve Remove plastic valve by rotating clockwise Unhook cable ONAUBRWNEH To Install Reconnect cable to water valve Install valve by placing it on the mount and turning counterclockwise Mount and adjust the control housing Reconnect hoses under dash and in engine compartment Remove hose clamps OBWNF Make sure that the heater hoses are held by the plastic clips that keep them away from the block the EGR system and other areas they can wear and leak Vents Blowing Black Foam Specks Inquiry have black foam blowing out my vents What do need to do to fix this Response David This comes from deteriorating foam sheets on air doors within the system popped all the air direction vents out with a small flat tip screwdriver There are only two small nipples one on each side holding the vents in place A little leverage and they come out easily BE CAREFUL THE SMALL CURVED WASHERS THAT PROVIDE THE TENSION TO HOLD THE VENTS IN POSITION AREN T ATTACHED TO ANYTHING figured coul
79. ng all new o rings coated with mineral oil or an a c specific silicone based lubricant such as Nylog made especially for o rings and antiseize on the outer threads don t get this near the o rings The lubes noted are not hygroscopic as is the ester or PAG used in the compressor and therefore will not corrode the fittings e Torques to condenser 25 Nm 18 4 ft lb from condenser 20 Nm 14 8 ft lb Apply rustproofing liberally to the fittings to prevent corrosion e Reinstall other parts and connectors and recharge system If you had a leak leading to discharge in an R12 system then convert to R134 Install the correct amount of oil per system specifications In 1993 cars a new type of condenser and compressor pipe termination was used requiring different pipes that terminate in non screwed ends Make sure you buy replacement condensers that drop into your car without the need for new pipes Should Flush or Install a Filter Tip from Underhood Service magazine Apr 2003 Condensers are trash collectors Any debris that comes out of the compressor goes straight into the condenser It s a low spot in the system so debris and oil naturally collect in the condenser But the debris doesn t stay put Refrigerant flowing through the condenser can pick up debris and carry it to the orifice tube expansion valve or back to the compressor Debris can plug up the orifice tube or expansion valve causing a blockage and loss of cooling Such blockages also ca
80. o 12V A Coolant temperature sensor in heater 1 4 1 Short circuit to ground M 1 4 2 Open circuit or short circuit to 12V M Generator 1 5 1 D signal level in generator A Solar sensor in speaker grill 1 6 1 Note illuminate this with a lamp to clear code l Servomotor potentiometer 2 1 1 Open circuit or short circuit to ground A 2 1 2 Short circuit to 12V Servomotor Drive 2 1 3 Pin 17 or 18 connected incorrectly to 12V A Servomotor 2 1 4 Motor activated for too long gt 10 seconds A blocked motor or failure of motor supply ECC Control Panel 2 3 1 Faulty temperature control A file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Blower Motor 2 3 3 Starting current too high motor seizes or turns sluggishly A Power terminal incorrectly connected to 12 V for the solenoids as follows 2 4 1 Water valve 2 4 2 Bi level 2 4 3 Vent 2 4 4 Recirculation 2 4 5 Defroster 2 4 6 Floor 2 4 7 Maximum blower relay 2 4 8 Compressor 2 4 9 Blower relay cars with air conditioning P Pr Sl Si Sb S S Sl SiS 2 4 9 Engine cooling fan relay cars without a
81. o keep debris in the system from getting into your new compressor costs 67 from www jcsonlinetoolshed com For leak detection get an Airmax LED penlight for UV leak detection from http www keep it kool com costs about 40 and a set of UV enhancing glasses from JC Whitney for about 5 You can purchase air conditioning dye injectors from NAPA The glasses are necessary to see the dye To seal pipe joints with o rings get some Nylog which is compatible with the o ring material and prevents corrosion Poor A C Performance Diagnosis Heater Valve Will Not Shut Off Robert Ritter A C suddenly did not cool as well as it had been or should be New compressor and accumulator installed a couple months ago Finally got around to snooping under the hood Pressures seemed fine and pressostat working ok Then observed that the vacuum hose to the heater valve had either been chafing or too hot and had a decent size hole in it Spliced in a new section of hose and everything seems to be back to normal Chris Mullet If the A C blows nice and cold at first start up cold engine and then starts blowing warmer as the engine warms up which is pretty quickly in a Volvo especially in hot weather then the heater valve or vacuum source to the valve is are suspect The default position at the valve with no vacuum applied is open or heat Quick A C Fluid Diagnosis Editor To determine whether your poor a c is due to low Freon start the engine and tu
82. orator drain spout pulling the thing out of the car Editor s Note Broken drain spouts are quite common so be VERY careful The mating surfaces are filled with sticky mastic which must be pried apart Warren K When I couldn t get the evaporator out because of the aluminum tubing loop on the bottom and the inlet and outlet tubes on the top nearly gave up Fortunately we started looking for any remaining screws That was the one mentioned by two posters out of sight in the right rear as mentioned above Tip The evaporator once disconnected from the a c tubes on the engine side of the firewall came out easily enough but the new one was as stubborn as a mule Note that the evaporator has two tubes that extend through seals in the firewall We finally got it through the firewall and hooked back up but that was the easy part The tough part was putting the evaporator cover back on this took almost 6 hours to do Tip take out all the insulating material around the drain spout that goes through the fire wall That will at least give you enough clearance to put the cover over the evaporator John Martin The foam donut that surrounds the plastic drain soit file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning should be peeled off the firewall padding and glued onto the lower cover for reinstallation then the donut and spout can settle back into the hole in th
83. ost are similar One hose is for the ACC and the other is for the temperature sniffer in the dome light if so equipped found that the hoses leaked at the check valves and using the small worm drive hose clamps took care of the leaks Prior to that the panel vents would snap shut as soon as you depressed the gas pedal Application of Vacuum to Water Control Valve Inquiry My heater won t shut off When is the hot water control valve in the engine compartment shut off Response Vacuum to close the water valve is only applied in max AC mode or when the MCC temperature selector is fully cold This varies according to the type of control system in the car MCC ACC ECC and the Volvo OEM service manual should be consulted for details of vacuum signals Heater Inquiry The heater in my 745TD still thinks it s summer The engine itself heats up in a normal period of time coolant temperature is at a normal level The coolant system builds up pressure in the expansion tank This morning put a piece of cardboard in front of the radiator still got cold feet so the thermostat is OK right The hoses that go towards the heating element are fairly warm The air from the top dash vents is not very warm and even on position 4 the flow is rather weak The middle vents are warmer and the flowrate is good The flowrate below is nearly neglible and the temperature is just above 0 C Response Dennis Hamblet Several suggestions e Your thermostat n
84. ould take about an hour e Worse case of mildew along with accumulated crud in the system Same disassembly procedure as above only remove the blower motor in addition to the resistor This requires removing the glove box and engine computer to secure good access then the blower motor and resistor Using a shop vac and a small tool kit such as the computer vac kits remove accumulated crud leaves dust etc by inserting the wand through the resistor hole and vacuum the face of the evaporator with a small brush attachment to remove mold dust etc from the aluminum heat exchanger Swab out the plenum with disinfectant through the blower motor hold Either use a treatment of Frigi fresh on the evaporator as above or go the whole nine yards with some Airsept a cooling coil coating treatment applied by spray such as a garden sprayer This costs around 60 and can be bought from Volvo dealers as part number 1161570 or from GM dealers GM Cooling Coil Treatment haven t used it but it results in an acrylic coating on the evaporator coils that inhibits mold growth GM claims good results This procedure is described in great detail in the Volvo shop manual for heating air conditioning systems While you are at it make sure as well that the cowl leaf screen is in place to limit ingress of crud which will be caught in the plenum and result in mold growth A new company makes a foam cleaner called DWD2 that cleans the front of the evaporator although so fa
85. r assembly located underneath or behind the glove box Get used to removing the blower motor to retrieve the debris from the inside of the squirrel cage You ll probably be surprised at what else you find in there Interior Water Leaks Loose Water Shields Clogged Ventilation AC Drains Tips by Steve Seekins courtesy of Guri Roesijadi Inquiry Water is leaking into my front footwells and soaking the carpets How do diagnose this Clogged Evaporator Drain Responses Dave Stevens Norm The single most likely culprit for the wet carpets is a plugged evaporator drain look on the firewall passenger side you should see the drain outlet there may be flush with the firewall or there may be a tube attached that runs down toward the frame rail The plastic casting for the lower air box half actually includes the drain spigot It is likely clogged with leaf debris or other stuff Suction it out by poking and then vacuuming Response found the drip tube grommet at firewall had deteriorated and cracked at bottom probably due to heat age Lathered with silicone caulk inside and out suggest placing a small downspout tube to extend drip pipe as the drain only extends about 1 2 thru firewall and water was dripping out and running back inside firewall Clogged Cowl Drains Leaf Screen Loose Check the air intake behind the hood there should be a screen under the slots and bonded to the bottom of the slots If it has come loose it lets
86. r it is sold only to trained installers You may also want to consider a product from ATP 1 847 967 6790 called Clean N Coat This uses the same two part chemical formulation as AirSept s coil coating except it comes in a convenient aerosol can obviating the need for a fancy blowgun and wand driven by shop air The product comes individually Part No AT 211 For further information on various cleaners and coatings see the article at I MCool com http www imcool com articles aircondition evap_stinks htm Real crud in the system clogged evaporator downstream dirt Bad news you will have to remove the plenum lower cover Do all of the above then around ten screws holding the lower plenum on These screws are in all kinds of weird places requiring extraordinary personal dexterity and a few socket extensions bendable extensions and magnetic tips The plenum cover is held on with thick mastic and is a bear to remove without damage Once you pull it off clean everything out insert the drain tube replace the mastic and put it back in place Don t do this unless all else fails Removing Panel Vents Inquiry How do you remove the vents from the dash Response JohnB A straight screwdriver used as a small pry bar works since the vents are just popped into holes in the sides But be careful there may be a cupped thin metal friction washer used to hold the vent in a set position To avoid losing this down the duct close the vent before r
87. rculation on and the controls set to max fan speed and dash vents accelerate until the air no longer flows from the vents and then put your hand down under the dash to see if air is flowing from the floor vent If this is the case then the recirculation vacuum motor is likely leaking Tip In a 960 you can pop off the panels on either side and put a clamp on the recirculating bellows orange hose and drive the car and see if the problem is gone or put a clamp on the floor side of the bellows Yellow hose IIRC or both as in our case and see if it goes away If it does the respective solenoid is at fault The vacuum reservoir located behind the glovebox may also have a leak common problem on this model Unfortunately in their infinite wisdom Volvo opted to make the canister part of the evaporator case VERY expensive replaced mine with a separate and independent canister Any good A C shop can do this You can also just permanently cap off the offending vacuum line probably orange or yellow although you will lose some functionality Remove the glovebox to locate the vacuum junction box with the lines installed All Replacing the Vacuum Motors Tom Irwin and Dick Riess developed a shortcut method requiring cutting the driver s side inner kick panel Another technique is listed from Beka at Brickboard Both are in the FAQ reference document Punting on the Fix Tips from GregV and John Sargent Assuming the problem is not the under hood
88. re It is a silver 3 16 cylinder with tapered ends one of which is white In either case i can tell you w o too much doubt that you will have to go behind glove box as the relay is there and the resistor is stuck into the blower case in that area also Blower Motor Fails Melted Heater Blower Fuse See the FAQ section Melted Heater Blower Fuse Heater Blower Motor Replacement Repair or Replace If your motor is squeeking you might be able to oil the bearings but most 740 940 motors have sealed and inaccessible bearings Plan on a replacement motor Tip from John McIntosh It is quite easy to dismantle the motor by bending the tabs holding it together Mine had been squealing and making sundry horrible noises The rotor was encrusted with iron filings and the bearings were dry lubed the bearings with 3 in 1 soaking the felts blew off the iron filings Mounted the rotor in my drill chuck and filed the armature with a smooth flat file finally polishing with glass paper not emery which am told is conductive The hardest part of re assembly is ensuring the brushes are held back whilst the armature is put in place This was done using pieces of wire Dont forget the cooling pipe when re installing My fan motor now runs silently and well Replacement Blower Motors Pre 90 740 Cars Earlier blower motors used generic units from GM GM mid 80 s blower motors for AC equipped Chevy Citations are exact replacements Another exact replacement
89. re routinely near 100 or more get the VOV for high temperature environments It has a slightly different operating range for best results in those conditions Tips from A C UPDATE Retrofit Vs Recharge Retrofitting Techniques Improving Cooling Performance amp Alternative Refrigerants Larry Carley I mportCar May 2000 Excerpts file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning One way to improve cooling performance when retrofitting an older R 12 system to R 134a is to install a variable valve orifice tube in place of the standard fixed orifice tube These aftermarket variable orifice tubes allow the flow rate through the valve to change for better cooling at idle and low speeds Such a valve can lower the A C outlet air temperature by as much as 5 to 8 degrees which can make quite a difference if the vehicle is crawling along in stop and go city traffic Installing a larger or more efficient condenser can also help compensate for losses in cooling efficiency with R 134a If the original condenser or evaporator is being replaced because of a leak damage or defect make sure the replacement unit has the same or better BTU rating Some aftermarket replacement condensers and evaporators may not deliver the same cooling performance and create a problem your customer didn t have before Location of Orifice Tube Chris Herbst Later cars have the orifice tube in
90. remove the glove box There are two small covers on either side of the box with screws under them The resistor pack is attached to the plenum with several wires close to the fan motor Replace it My car is 14 years old and has the original resistors Make sure the blower motor works OK Specific to 1992 740 file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Inquiry Fan switch only works on 5 no 1 2 3 4 Is it the switch or is there a resistor pack or can it be the motor Response Abe Crombie There are two things that come to mind dependent on how a 92 is wired There may be a blower relay on the case behind glove box It passes all the current from resistor to blower but on high the relay is energized and its contact switches over and feeds direct 12 v to blower saving the switch from having to carry the high amperage If the contacts on the lower speed side are burnt this failure would occur The other is the resistor itself believe a 92 has this feature but it might not have occured until 93 anyway the resistor may have a temp fuse integrated into it that will go open if the blower resistor has debris around it or if the blower motor drags Either of these two will make the resistor get hot enough to trip the temp fuse If the resistor has the temp fuse it will be a green ceramic covered resistor and the temp fuse will be adjacent to ceramic co
91. rmation is suggested as being possibly earlier or possibly all models because of the inability to verify this information at the time of writing Model years are included where known The file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning purpose of this review is not to include every screw pipe and switch in the A C system but is merely to educate about the fundamentals of two different kinds of A C system found in RWD Volvo models from the mid 1980s to 1998 940 Models This system also applies to 700 series cars and 960 models It also applies to ALL 240 models from 1991 1993 The mechanics of the system are the same between climate controlled and non climate controlled systems electronics vary and are beyond the information covered in this review The 900 system is a clutch cycling orifice tube system abbreviated CCOT The CCOT system cycles refrigerant through the following components Compressor begins high pressure cycle at compressor outlet Condenser Fixed orifice tube locations vary slightly ALL are high side fixtures Transition from high pressure to low pressure side via Fixed Orifice Tube Evaporator downstream of F O T Accumulator dryer NOTICE this is on the LOW SIDE Refrigerant returns to compressor via suction side OUBRWNE The CCOT system has the accumulator dryer large silver can at the firewall on the LOW PRESSURE SIDE
92. rn a c and the fan to on Open the hood Locate the receiver dryer the big aluminum can up near the firewall on the passenger side in LHD cars Push the spring clip on the low pressure switch connector mounted on the side of the dryer and remove the connector Using a paper clip short the two connectors If the compressor engages your Freon is low Inquiry have a 1993 945 turbo The air conditioner 134a works ok on the highway when it is less than 90 degrees outside but only makes the car bearable in city driving checked the charge level and it appears to be fine Does anyone have any ideas Response Abe Crombie had a car like yours and the a c was fine in the southeast US summer The problem could be any one of several possibilities like heater valve not being closed at full cold position of the temperature control partially blocked condenser cooling fans not working correctly etc The only way to know you have the right charge level is to recover and then refill a c system The hot water valve should be getting vacuum via a vacuum switch on the heater control when the temperature knob is turned that last little bump to the left Bugs and stuff will block the condenser over time and this will make performance suffer even more on R134a systems The electric fans must work properly for the same reasons Fan Operation and System Charge Inquiry Need help with my 91 740 Turbo Wagon A C system It works great when I m on the highway
93. s diaphragm unit It requires removing a lot of under dash parts and ducts and then standing on your head to reach two extremely hard to get at nuts would try blocking the yellow hose with an old style fuse the glass w metal end cap kind and see if you notice any real compromise in operation you won t ever get the full flow to floor and you ll always have some air out of defrost any time that you aren t on a c Vacuum Check Valve Failures Inquiry have a 1990 760T and the H AC is losing vacuum during low vacuum and during boost from the turbo There is a tee above the intake that has two black amp white fitting that connect to two smaller hoses that go to the fire wall suspect these supply vaccum to the H AC but does anyone know if these are actual check valves to prevent vacuum or boost from entering the system Response RL There are numerous sources of potential vacuum leak including some of the vacuum motors bellows on the actual heat AC system but those two valves are a common problem They are check valves to prevent loss of vacuum and if you bench test them individually you may find that they perform well under a fair amount of vacuum but that as soon as you try minimal vacuum the valves will give up You may try cleaning them out in WD40 or some rubber softening file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning substance but fai
94. s immediately because moisture may damage the drier Since was replacing the compressor too my parts supplier suggested a new drier Might be something to consider with a new evap anyway 5 Remove right side sill trim side panel panel under glove box and the glove box Removing the dash is not really necessary Doing this job is much easier file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning if you remove the front passenger seat then lay some padding down on the floor 6 Disconnect control module cable clip remove control module 2 screws and its mounting bracket 3 screws 7 Disconnect electrical connections to blower and resistor 3 plugs Remove 3 screws to remove the blower 8 Remove approximately 9 screws around front side and back of the evaporator housing Note that 740 s 760 s 940 s 960 s may have different evaporator housings so the number of screws and procedure may vary What you are trying to remove is the lower half of the duct which extends from the cylindrical portion containing the blower going to the left to a point where you may see a label for the evaporator Coming down vertically from this point underneath you will see 4 circular grommet looking things That is the other end of the lower housing you will need to remove The upper and lower halves of the evap are adhered with sticky butyl mastic and you will have to pry them apart
95. speed the a c works great The Volvo manual says it is a fuel economy issue whereby the a c compressor cuts off during acceleration but this should occur only at wide open throttle file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning Responses Problems are likely to be found in the vacuum system that controls the opening and closing of the flaps in the AC vent ducts namely the vacuum control check valves diaphragms and or defrost floor vacuum motor located just above the accelerator pedal or in the integral vacuum reservoir built in to the evaporator case Faulty Control Unit See the FAQ section below about solder failures in the control unit that can prevent the compressor from engaging Faulty Low Pressure Switch Inquiry When the A C button is ON my compressor is not engaging nor the cooling fan is coming ON Supplied 12V to the contacts at the low pressure switch compressor did engage charged the A C to 30 PSI on the low side installed the switch back but again same thing as above Response Chris Hollis had the same problem with my 94 945T You might check continuity of your low pressure switch had a bad low pressure switch bought TWO bad switches from Volvo before bought a third aftermarket switch from a place called The Volvo Site part number 1343216 forget the exact pressure ratings but they switch off open around 20psi a
96. stalled in the expansion pipe The joint at which to access the expansion valve is located along the right side frame rail in the engine compartment It is where the high side pipe gets a little bit bigger in diameter You ll find the OT in that joint The earlier cars with very small diameter pipes at the firewall had it in the evaporator The expansion tube location started in 1991 believe but that is not a guaranteed model year for the change As a 1993 model your car is sure to have the OT in the expansion tube R134 versus Refrigerant Alternatives Editor The R134 conversion debate seems to be over and it is widely accepted as an alternative to R12 Numerous other refrigerants are also approved by the EPA as having met safety and environmental criteria Unfortunately the EPA does not test these alternative refrigerants for compatibility with refrigerant oils elastomers and other components in your car s cooling system Santech Industries a major producer of air conditioning components has done some tests and found R134 the only acceptable substitution product for most applications See the link for more information in the testing and reference section http www santech com Volvo uses HNBR in its black and yellow o rings some earlier seals were blue neoprene They also recommend the use of ester oil as the replacement lubricant in R12 to R134 conversions After testing HNBR and ester oil Santech rated the following fluids for
97. stuff into the air box To repair you need to remove the cowl piece three bolts along front edge under rear edge of hood no need to remove hood and remove the wiper blades and rubber pieces Middle bolt is usually hidden behind the rubber weather strip Cowl moves forward and then pulls back off toward the windshield There are pins on each side that fit into slots on the cowl It also fits into clips along bottom edge of windshield See the section in Electrical Wipers Getting the cowl back in is a bit more difficult than getting it out First often the small plastic pins at file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning the ends break they are sort of a blind plastic rivet affair good to have one or two new ones on hand Second getting the cowl properly lodged under the clips at the lower edge of W S can be tricky and if you don t the cowl will not lay down against the lower edge of w s properly Push down on the cowl while a helper pushes back against the firewall edge Leaf Screen and Drains The leaf screen is fastened to underside of cowl with sticky black adhesive caulk called body caulk The black glue can be replaced with Butyl Tape 3M WindowWeld Ribbon Tape in 1 4 inch diameter from an auto parts store which is the stuff used to glue in an older windshield this lasts forever Duct mastic from a heating contractor might also work W
98. t is kind of the Don Foster approach in his case replacing the heater motor on 240s There are 3 motors and fortunately the most accessible is generally the culprit and has two hose connections First try a Mighty Vac and hook up a tube to each of the connections and see if they hold a vac If one doesn t you have a bad vacuum motor Have to disconnect the hoses on the motor first of course Do your diagnostics first Response Abe Crombie To expand on what Dick posted The likely culprit assuming the vacuum supply is coming in correctly from the engine compartment is the floor defrost servo It is a double acting no vac centered floor defrost split vac on blue hose defrost vac on yellow hose floor and has a boot on the floor side that retains vac on that side of diaphragm The boot fails and you lose vac Blocking yellow hose fixes it simply with compromised floor air volume floor would be floor defrost All of this aforementioned stuff is usually the case if symptom is loss on acceleration Editor A new vacuum servo costs around 60 if you choose to replace it 740 or 760 Tips The 760 with ACC has an electric vacuum valve set to left behind glove box and a cold soldered joint on it at one of the end pins will cause no response in any position which defaults to floor defrost The 740 with MCC has a rotary vacuum switch linked to slide lever for vent selection and the hoses behind panel white is source can be crushed or the feed hose whi
99. te above accelerator pedal at firewall can be crushed The 760T with ECC has a floor defrost servo sprung to return to center when no vac is applied This will direct air reaching this part of the air distribution housing to the defrost and to the floor outlets The yellow hose applies vacuum to the side of diaphragm that will extend the servo rod to push the door up blocking most of the defrost vent air and directing 90 to floor The seal that rides the servo rod can dislodge or just split and you have the result you observed air stops coming out of any vents during turbo boost manifold pressure instead of vacuum indicating a leaky push pull vacuum servo Disconnecting the yellow hose will not allow you to get full floor air When the floor air position is selected by you or by the ECC logic the air will be split between floor and defrost This is likely not a problem unless you have really poor leg circulation that gives you a severe tendency to cold feet long after the rest of your body is warm The logic in the ECC always has the floor position selected on this servo when it is directing air to the dash face vents so if it leaks you lose the vac for entire system and all the doors go their respective sprung positions VR ge 960 90 With ECC Tips Tip from Steve Long for 960 ECC If you have done the tests above and you are still having a problem while in recirculation mode try to pinpoint the cause to a specific vacuum motor With the reci
100. ter core If this plastic bodied unit cracks you will instantly lose a majority of your coolant The engine side valves installed in air conditioned cars are exposed to much more heat and have a shorter lifespan than the passenger side valves in heater only cars The engine side units last about eight years and should then be discarded When you replace this consider new heater hoses as well Part Quality The rather pricey Volvo OEM valve 9447896 is top quality and lasts a long time Quality goes down from there all the way to the cheap MTC brand valve for which several anecdotal reports on Brickboard note avoid since the valve failed within a year or so of installation and cooked the head gaskets For a decent alternative try the FourSeasons domestic water valve part number 74612 widely available in parts stores for about 12 John Martin Drop in replacement for the OEM metal and plastic heater control valves used in the 740 and 940 is available from Ford dealers Motorcraft part number YG 136 List price is 31 68 local dealer sold it to me for 18 80 Side by side the valves are clearly the exact same thing Local Volvo dealer wanted over 80 Tasca wants 64 Quite a mark up from the red box to the blue box Some googling shows it s also available as D4AAZ 18495 A for Fords and under other numbers for some GM applications too You will need to source a vacuum tube adapter as the nipple on the Motorcraft valve may be smaller than on the
101. the unit Look for who manufactured it Murray Moog Four Seasons AC Plus are all EXCELLENT rebuilds ASK the parts guy who makes their private label stuff Can the clutch be replaced without discharging the system Yes One last note Diesel Kiki s that were converted to 134a are shit Since you are going whole hog get a 134a pump new receiver drier do it right 12 is just too much hassle Response Lamar You can get a new one for just over 200 at Autozone or Advance They come ready to use either R 12 or R 134a just replaced one on an 88 740 Sanden Models See the Sanden Corporation website under Support for a full service manual and parts information for their compressors Lubrication Capacities Use the correct compressor oil Volvo 7XX 9XX Air Conditioning Compressor Lube Capacity Chart Note OEM lube oils for R134 OEM systems come in several PAG viscosities depending on compressor one for Sanden SD 7H15 Volvo p n 1161425 2 one for Seiko Seiki SS 121DS5 Lubricating Oil Volvo p n 1161426 0 and one for Diesel Kiki Zexel Volvo p n 1161407 They may not be intermixed R12 Mineral Oil Note R134 retrofit oils are always ester Volvo p n 1161442 7 R134 Retrofit Ester Oil R134 OEM Install PAG Oil Compressor Model Metric L English Qts Delco R4 0 30 0 32 Diesel Kiki DKS 15BH 0 20 0 21 Sankyo Sanden SD 510 0 24 0 25 SD 709 0 24 0 25
102. ur tech to trace it that much more easily especially the leaks that are intermittent or hidden See Tools above for a source of UV lamps and detectors If you do use a dye add no more than 1 4 ounce at a time and only file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning twice More than that may dilute your compressor oil If you inject a dye into an R134a system make sure it meets the SAE J 2297 standard for refrigerant and oil compatibility One dose of dye is enough Adding extra shots of dye not only won t help but because dye changes the viscosity of the oil excessive use can adversely affect compressor life A C Recharge Tips Recharge Connection Volvo used R 12 in cars up through 1992 then R 134 in 1993 cars Inquiry Can anyone tell me how to distinguish between the high and low side connection in order to recharge the air conditioning on my Volvo 1990 760 4 cycl turbo Replies Bob and JohnB The flow in the system goes from the compressor under high pressure to the condensor Then via the receiver dryer to the evaporator inside the cabin From there it flows at a low pressure the suction side back to the compressor Locate it ll be the low side High side port is on the compressor low side port near the hose from the firewall to the compressor on the big silver round cylindrical container receiver dryer There should be a cap covering
103. vacuum check valve it is probably a leaking vacuum servo After reading the FAQ s was tempted to go under the dash and tear everything apart However talked to the guy at the volvo dealership and he recommended a less then 3 perfect solution The servo valve that is going bad is the dual action vacuum servo on the outside of the heater box used to control the recirculating air function Access is above the driver s right foot take down the panel above the pedals and the knee deflector You can check it by removing the yellow vacuum line from the servo and applying vacuum to the nipple on the servo It probably won t hold vacuum Replacing the servo is almost as much work as ugh replacing the heater core If you simply plug that one vacuum line as shown in the photo right the recirculating function will not work but the rest of the system will work fine He asked me file C Users Steve Documents Volvo 20FAQ 20Updated HeatingAirConditioning html 01 13 14 10 12 34 PM Heating and Air Conditioning how many times a year actually use the recirculate button and if it was worth 4 6 hours to tear up my dash He made a good point so consider this as another option to actually fixing the problem Replacing Vacuum Servos in ACC Equipped 700 900 Cars See the file link for more information Homemade Cabin Air Filter Tip from Rafael Riverol My 95 960 has sucked enough tree leaves pine needles etc through fan blower air intake and
104. x Apparently Volvo made a design change in the motors and the replacement ones require a slight mod to the box In fact the IPD kit contained the part from Volvo for the mod TheVolvo shop manual also describes the mod so am convinced it is a Volvo design change and not an aftermarket attempt to make a universal motor fit a Volvo My 87 745T apparently had already eaten a motor and the mod had already been made So replacing this motor was a piece of cake My 88 745T had not had its motor replaced so had to do the mod Follow the above procedure and read the directions for the modified mounting plate that came with the motor You may need to cut off a short plastic drain pipe using a hack saw blade apply some sealant to the adaptor ring screw it in place and drill a vent hole No big deal Then mount the new motor solder the wires and close everything up 760 with ECC 960 S V90 Blower Motor Replacement Remove the battery ground lead the passenger kick panel the glove box the kick panel in front of the door the a c ductwork the bracing crashbar left bolts remove easiest from radio compartment and the right crashbar mount Remove the terminal strip and bracket holding the back of the motor then the electrical connector and the motor itself When reinstalling don t forget the rubber gasket around the housing The vent system in the 960 can suck paper and debris very easily when in recirculation mode It usually ends up inside the blower moto
105. you are replacing a hose inspect for shavings and flush as needed Receiver Dryer Replacement Editor When replacing the receiver dryer canister measure the refrigerant oil contained in the old unit and fill the new one with fresh oil of the same grade and quantity Use new O rings compatible with your refrigerant and lubricated with the correct oil Use two wrenches when installing so you do not overtorque one side of the fitting Evacuate the system using a vacuum to pull any moisture out then refill with refrigerant A C Compressor Failure General Notes by Larry Carley Import Car Magazine The most common symptom of a compressor failure besides no cooling is a seized compressor It won t turn when the magnetic clutch engages and you may hear squeals of protest from the drive belt Or the belt may have already broken or been thrown off its pulleys Loss of lubrication is unquestionably the most common cause of compressor failure This can happen when there s a refrigerant leak somewhere in the system that allows refrigerant and oil to escape Typical leak points are hoses hose and pipe connections O rings and flange gaskets the evaporator condenser or the compressor shaft seal An electronic leak detector or dye should be used to find the leak so it can be repaired A restriction inside the A C system can also starve the compressor for oil Oil circulates with the refrigerant so if the orifice tube or expansion valve is blocked it may

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