General Notes.  [Query:] 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 I can't locate the reservoir in this car. Does anyone have any ideas?  [Response: Rich Kelley] The problem you describe sounds like one I've seen quite a bit on 960's. It sounds like a ruptured diaphragm on the flapper control solenoid. There is an illustrated, detailed repair procedure at Replacing Vacuum Servos in ACC-Equipped 700/900 Cars.   It's located on the drivers side. Take down the knee bolster and look up on the side of the climate control box. There are two vacuum controlled solenoids there and the one that usually goes is the one with 2 hoses going to it. It is very hard to get out, as it is held in place by 2, 10mm nuts on the inside of the box.

Look Under the Hood First.  [Tip from Bob]  Start by checking the vacuum supply hose under the hood. Under-dash leaks are extremely rare. 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) white plastic hose. It goes from firewall near heater hoses and winds its way to a tee with a check valve conected 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.

Try Cleaning It.  [Tip from Larry Jacobson] Before doing any cutting and sawing, your arm up into the air intake that goes up in back of the 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.

Replacing the Vacuum Motor.  [Query:] 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, I have done one on my 91 940SE. It 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 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.
You don't mention whether it is a 740 or 760. The 760 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 is 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 (white) above accelerator pedal at firewall can be crushed.
[Response: Abe Crombie, regarding 1990 760T with ECC: air stops coming out of any vents during turbo boost (manifold pressure instead of vacuum), indicating a leaky push-pull vacuum servo)]  The Floor/Defrost servo you discovered leaking is 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. 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.

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. Just remove the trim and panels around the floor, and remove the ECM from its mount. The ECM bracket is them easily unscrewed for removal. The blower is just above and easily replaced with 3 screws. I had to rewire the connector with a soldering iron, but that was no big deal.

My '88 745T had not had its motor replaced, so I had to do the mod. Just do the above procedure and follow the direction for the mod that came with the motor. Needed 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 mounted the new motor, solder the wires, and close everything up.

In both cases, the squealing went away and life quieted down a lot. One observation I made was that the cage on the new blowers are not as deep as the OEM blowers. Hence, the cage will not come as close to the air input port of the duct work. This may cause less efficiently in moving air to the cabin of the car. i.e., less air moving through the vents. Despite what I think is less air flow, I still get plenty of heat and AC. At least the squealing is gone, so I can't complain.

[First comment: GM mid-80's blower motors for AC Chevy Citations are exact replacements. Also: look for an '81 Delta 88 w/ air conditioning blower motor. Also: The replacement for the 760 series fan motor is a standard GM fan motor. The NAPA part number is 455-1076. Also: fan motor for a '87 760. The clerk responded, $57.94 and we'll have to order it. Then, I said ok, Try a '83 Chevy Impala with AC. In stock and $17.99 with lifetime warranty.]

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.]

[Second Comment:] After posting an e-mail question regarding heater blower motors on the Swedishbricks mailing list, I 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.

[Query]  Need help with my '91 740 Turbo Wagon A/C system. It works great when Im on the highway (ie. speed greater than 40 mph) but when I slow down or stop I lose cooling. I believe that I am not getting good condensing action even though there is a belt driven fan on the engine. I suspect that the small electric fan in front of the radiator needs to come on with the A/C.  [Response: Rob Bareiss]   YES, your electric fan is supposed to be on AT ALL TIMES when the AC is running. My guess is if you pull your grille out, and reach in there, you'll find it does not turn freely. So the motor probably burned out when it seized up. Just 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- if it's leaking at all, consider a conversion kit to R134 refrigerant. It's at the point now that it's almost cheaper to convert it than to recharge with R12. A kit costs $61 from Volvo, and R134 ought to be less than $50. If your system was fully discharged, a full charge of R12 would be over $110. A partial charge would be cheaper, and since yours works mostly, it's probably got close to a full charge in it.  Keep in mind also that you'll be getting a new expansion valve and receiver/dryer with the Volvo kit, so it ought to be pretty efficient for years.

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.

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.  The following kits are available from Volvo:

9145660-8 -- covers 1985-92 740 models, 1983-87 760 models, 1991-92 940 models, 1989-91 780 models and1983-86 700 models
9145666-5 -- covers 1991-92 240 models
9134808-6 -- covers 1975-90 200 models
9145661-6 -- covers 1988-90 760 models, 1991 940SE and 1992 960 models.

[How to retrofit R134 into R12 systems:] Great website from Dave Urban showing the instructions and illustrations for the Volvo retrofit kit for 7xx cars and Dave's annotated comments from his own changeover: http://www.prismnet.com/~davurban/AC_RETROFIT/Page_1.html
[More how-to:] About a month ago, I retrofitted my wife's 88 765T to R134a, using the Volvo retrofit kit, which contains a new receiver-dryer, orifice tube, o-rings, and ester oil. I did it right. First, I had the system evacuated. Then, using compressed air, I blew out all the lines. Then I installed the new receiver-dryer and orifice tube, and then I pulled off the compressor (that was a job!) so I could empty the old oil out and add the new oil. Volvo gives you the oil for this, but doesn't tell you how you're supposed to change the oil without removing the compressor -- and apparently they don't expect you to, since they don't include o-rings for the hoses. What, do some Volvo compressors have a drain plug on the bottom? Mine has a fill plug on top, but no drain hole on the bottom. Anyway, I took it back to the shop, had them draw down a vacuum on the system, then recharge it with R134a (it takes LESS R134a, BTW). The result? 41 degrees F at the vent -- which is Volvo spec for the '88 765T. This was with the car sitting at the A/C shop, just idling, too.
[Lack of adequate cooling after retrofit:] I would have to say that the person responsible for updating this particular 7xx system missed something. I 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). Inoperative 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 I 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% larger 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).
I recently did the same conversion on my 1989 745GL. I'm not terribly happy with the performance at idle either. After some experimenting I've decided there are a few things that can be done to improve things, none of which I 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 will 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.

[Another Comment:] It is not a good idea to convert your R12 car to R134a or any of the R134a-based refrigerants (FRIGC and Freeze-12 come to mind). They are, relatively speaking, extremely inefficient refrigerants. Also, they are HIGHLY incompatible with R12-type oil. They operate at radically different pressures, so calibration of R12 expansion valves won't be optimal. Also, since 134a is so inefficient, one must use larger compressors, condensers, and evaporators to get the same level of cooling as from an R12 system. This is difficult and expensive to do on an existing system, so you get much less cooling with 134a. Perhaps most troubling is that R134a, unlike most other refrigerants, is not chemically inert. It is reactive, and has been shown to cause reproductive damage and is a suspected carcinogen.

Now that I have detailed some of the disadvantages of converting, let me outline what you would need to do to convert to 134a so as not to shell any of the components [Editor's note: see above remarks for Volvo-specific information and retrofit kits.] You're going to need:

Barrier-style hoses (The R12 hoses are permeable to the smaller R134a molecule)

All new seals and O-rings (ditto above)

A rebuild or thorough flush of your compressor. Which one you will need depends on the design of the compressor. Early Chrysler, York and Tecumseh compressors, for instance, use an oil sump and pump which cannot be "flushed" of oil like non-sump type designs, and because 134a is so violently incompatible with 12-type oil, you have to get ALL of the old oil out.)

New receiver-dryer with XH7 or XH9 desiccant

People often cite low cost of the R134a refrigerant itself as a reason for converting. Have a look at that list above and it becomes readily apparent that $80 worth of R12 vs. $20 worth of R134a is an irrelevant comparison.

There are other legal, safe, effective and efficient options if you have decided, for whatever which reason, to convert your system to a non-12 refrigerant (more on this later). Various companies have brought various refrigerants to market. Many of them have been minimally tested, have disadvantages similar to 134a, and/or other deployment difficulties. For instance, a lot of the new refrigerants have a very difficult time carrying any kind of oil back to the compressor. R12 has very good oil carrying capability, so the vast majority of existing compressor designs are meant for use with a refrigerant that will bring the oil back and lubricate the compressor. New oils have been developed to work reasonably well with the new refrigerants, but industry data confirm that compressor failure rates are up since the advent of refrigerants that don't carry oil as readily.

My own research and testing has turned up two very interesting refrigerants that seem to work extremely well, with minimal deployment difficulties. Those are R406a, and GHG-X4. Both refrigerants were invented by a Professor George Goble of Perdue University in Indiana. I don't work for the company, I don't sell the stuff, I have no association with Mr. Goble or anyone else on his refrigerant staff, except I've communicated with them by e-mail a few times. I point this out to indicate that I'm not trying to sell something, don't have any particular agenda or ulterior motive, etc.

Here is a rundown of some of the advantages of these two products as conversion refrigerants (actually, EPA's preferred term is "substitute" or "replacement" refrigerants.)

They are MORE efficient than 12, yet they operate at similar pressures, so the expansion valve calibration will remain optimal and your existing condenser and evaporator will function MORE than adequately. (improvement is usually quite quantifiable with a good A/C thermometer in the center outlet. Air outlet temps are usually 2 to 12 degrees colder than with 12.)

They are completely compatible with R12 type oil, so no system flush or compressor rebuild.

Both 406a and X4 have passed all UL, DOT, EPA and ASHRAE tests for safety and utility in mobile and non-mobile systems. They are certified nonflammable.

It is a ternary zeotrope, which means it is made of three components. This is an advantage AND a disadvantage: Leaking systems theoretically must be completely evacuated and recharged. Also, charging must be done in a LIQUID CHARGE fashion. (Note, this also explains the improved efficiency. The three factions boil/condense at slightly different temperatures. This is known as a temperature "glide" and effectively increases the usable condenser/evaporator area, creating the increase in efficiency.)

You still need barrier hoses, because R12 type hoses are permeable to the smaller R406a factions' molecules.

Ditto new seals.

New fittings and system labels are still legally required, since EPA has determined that each individual refrigerant product must have its own set of uniquely-threaded fittings. Adaptors and replacement fittings are available. (Note, this is a legal requirement. Physically and chemically, these two Rs are completely miscible and compatible with R12.)

Shops using R406a and X4 may be more difficult to find than those using 134a. Production and distribution of 406a and X4 has been ramping up steadily for the past several years.

Some will tell you that R134a is the only legal refrigerant. That's wrong. Go to the EPA SNAP (Significant New <refrigerant> Alternatives Plan) homepage and see for yourself that many new refrigerants, including 406a and GHG-X4 have passed all the safety tests, are certified nonflammable/non-corrosive, etc.

Some will tell you that 134a "moves more heat" than R12. That's also wrong. Some will tell you that no flush, rebuild, or anything else is needed when converting to 134a, and that you can just drop 134a into an existing system. For most systems, That's dangerously wrong.

Information on conversions and refrigerant alternatives can be found at:

Screen is fastened to underside of cowl with some sticky black RTV type stuff.  Getting the cowl back in is a bit more difficult than getting it out.  First, often the small plastic pins at 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. Get the plastic leaf/snow guard from Volvo that goes over the vent opening - helps keep the leaves and crud out.

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 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.

Diagnosis Notes.
[Response: Patrick Paul] If you have power to the pressure switch then all components before that are OK as far as turning the power supply off and on.  You can go to 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 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.  [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 to the solder connections, but this is very rare.

Re-Soldering the Control Unit PC Board.
[Response: Philip]  We had intermittant AC problems on our 94 940 turbo that were cured by resoldering a bad solder 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 aound the outside. Re-soldered it and save $400 for a new one.  [Response: James Abercrombie]  There are no service parts for this unit. The wave solder process demons have struck this unit. The solder cracks at the points where the high current load is passed through the PC board connections. Soldering is usually all it takes.
[Tips: Patric Paul] Remove the radio.  Take off the cover on the front of the control unit.  It just clips on.  There are 2 or 4 screws that hold the CU in place; take them out and disconnect the CU. Remove the silver panel (clips and screws).  Take out the screws for the circuit board and examine it.  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 HVAC contoller's circuit board, as suggested. All this stuff is integral with the HVAC control panel in the dash.  Once 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, and look for the cracked solder joint. Mine was easy to see, but I do know that they are not always so. Resolder, 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. I am a physicist by training, but years of working in failure analysis in the telecommunications industry tells me that the solder joint in question is under-engineered. I just scraped away some solder mask to allow greater wetting area, which I think will help prevent future failures.

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;  I: No warning to driver]
 

DTC	Fault Component & Description	Fault Class
111	Fault-free
	Ambient temperature sensor (on blower housing):
121	Short-circuit to ground	A
122	Open circuit or short-circuit to 12V	A
	Interior temperature sensor (in roof light):
131	Short-circuit to ground	A
132	Open circuit or short-circuit to 12V	A
	Coolant temperature sensor (in heater):
141	Short-circuit to ground	M
142	Open circuit or short-circuit to 12V	M
	Generator:
151	D+ signal level in generator	A
	Solar sensor (in speaker grill)
161	(Note: illuminate this with a lamp to clear code)	I
	Servomotor/potentiometer:
211	Open circuit or short-circuit to ground	A
212	Short-circuit to 12V	A
	Servomotor Drive:
213	Pin 17 or 18 connected incorrectly to 12V	A
	Servomotor:
214	Motor activated for too long > 10 seconds	A
	(blocked motor or failure of motor supply)
	ECC Control Panel:
231	Faulty temperature control	A
	Blower Motor:
233	Starting current too high, motor seizes or	A
	turns sluggishly
	Power terminal incorrectly connected to
	12 V for the solenoids as follows:
241	Water valve	A
242	Bi-level	A
243	Vent	A
244	Recirculation	A
245	Defroster	A
246	Floor	A
247	Maximum blower relay	A
248	Compressor	A
249	Blower relay (cars with air conditioning)	A
249	Engine cooling fan relay (cars without a/c)	A