92 940 A/C repair

Ben-jamin · Post by **Ben-jamin** » 01 Sep 2010, 20:53

So its time to give my Volvo some love again and fixing the A/C is at the top of my list. There may be more than one issue with the A/C as it has not worked since I purchased the car. The one thing I do know is that it needs a new clutch because the pulley is frozen, and it should turn freely without making noise as I understand.

Plan
1. Assume the compressor is good and replace only the clutch without removing the compressor at all. This way the system stays charged and I don't need a mechanic to charge me $300 in labor to evac and recharge the system.
2. Put on the belt and see if the air blows cold.
3. If not, jump out the freon low temp switch momentarily. This is located on the passenger side near the firewall. If the compressor kicks on then I just need a charge. ($40 can from parts place)
4. If it does not kick on, jump the wire coming off the A/C clutch from the connector near the engine block to the positive battery terminal. If it pulls in and runs then the problem is electrical. I will need to find what is holding the 12V from the clutch.
5. Check the fuse, and the switch (which I learned can be replaced with the antenna switch), and the relay.

Questions
1. Am I on the right track? Any suggestions?
2. How do I remove/install the clutch.

Post by **JDS60R** » 01 Sep 2010, 21:57

Do you have r-12 or R-134a refrigerant (sticker under hood tells you)?

Is there any pressure left in the system?

Ben-jamin · Post by **Ben-jamin** » 03 Sep 2010, 17:04

It's r-12, and yes, there is still pressure in the system.

Retired MVS Contributor · Post by **Retired MVS Contributor** » 03 Sep 2010, 18:44

Ben-jamin wrote:It's r-12, and yes, there is still pressure in the system.

Even if there is still freon in it, how long has it been inactive?...Freon will leak off if the compressor shaft seals are not "exercised" regularly...How did you measure the pressure, what was the pressure, and what was the ambient temperature when you measured it?...A property of R-12 is that the pressure will closely follow the ambient temperature...If the temperature was 75 degrees the day you measured the pressure, and if the system is fully charged, the static pressure should have been 77 PSI...100 degrees?...117 PSI...BTW, the switch near the firewall on the passenger's side is not a temperature switch, it is the low pressure cut-off...

A big problem is the availability of freon...If you can get it at all, it will be VERY expensive, well over $100 a pound...An option is to convert to R-134, but that will be expensive too...You need a conversion kit (fittings, etc) and the system has to be purged of the mineral oil that was used as a lubricant in R-12 systems...Mineral oil is incompatible with R-134...That means remove the compressor, empty it, measure the amount of oil you got out, and refill it with PAG oil...The same applies to the evaporator and condenser, they have to be flushed of the mineral oil and replaced with PAG...The accumulator will have to be replaced...It will also have a small amount of oil and that will have to be replaced with PAG...It is not worth while trying to save it, just measure the oil and add the same amount to a new accumulator...

There are other refrigerants available that do not require an oil change, will mix right in with the freon, it is not necessary to evacuate the system, they are environmentally approved, and they are cheap...AND THEY ARE COLDER!!!...They are hydro-carbons and some will say they are inflammable...So is R-134, R-134's flash point is 378 degrees...We are all sitting on 20 gallons of gasoline...What is more inflammable than that?...The A/C system only holds 1 1/2 pounds or so...

Post by **JDS60R** » 03 Sep 2010, 19:02

I would convert and be done with it.
Replace the compressor - not all clutches come off easily and R-12 is ridiculously expensive. They should pay you to evacuate it.

When I converted my friends 240 we took the time to replace o rings and worn parts (compressor etc) . The new system was ice cold and he can charge it cheaply if he ever needs it.

Retired MVS Contributor · Post by **Retired MVS Contributor** » 04 Sep 2010, 15:33

If you are sure that only the clutch bearing is bad, the compressor should be able to be turned by hand without any noise...If that is the case, I would put the belt on, run it, and check the A/C out...You will not be able to cycle it off because of the bearing, but you will know whether the rest of the system is good or not...If everything else is good, the sensible and cheapest thing to do (in my mind) is replace the clutch...The clutch will set you back $110 at FCP Groton, and the compressor wil set you back $300...I have never had much trouble getting the clutch off...Leave the belt on so that the puller cannot turn and hit it with an impact wrench...