My 94 Volvo 940's A/C has not worked for about a year now and I want to finally fix it. I was almost sure that it was low on gas causing the compressor clutch not to engage but a friend put a gauge on the gas refill fitting and it shows that it is full and has pressure. The compressor clutch does not want to engage for some reason. Could it possibly be a fuse or that the system is low on gas after all. What do you people think I should check next and where is the fuse for the A/C compressor located, I checked behind the ash tray but it's not there. Thanks for any help that you can give me.

 

First short out the switch on the drier by using a paper clip to see if the compressor kicks in, and this will mean that the switch is bad signalling low pressure and keeping the compressor off. Change the switch... If the compressor does not come on, then it may be bad or the control panel may be faulty.

 

Do can one just stick a paperclip in there and walk away unscathed? Or are some precautions needed?

 

This might be a dumb question but if it were to end up being the low pressure switch can I remove and replace it without loosing any refrigerant. Thanks for your help lev.

 

The low pressure switch on the accumulator is on a schrader valve, so you can remove/replace it without losing refrigerant. I'm thinking that's probably not your problem though..

 

Thanks for your reply Joseph. What do you think could possibly be the problem.

 

Numerous possibilities. Here's a couple of examples:

I'm fooling with a '92 240 that belongs to a friend. It has an orifice tube system similar to yours. Based on his complaint that it would cool "some" at idle, but not going down the road,and the fact that I noticed that the compressor was short cycling (In the heat we're having in TX these days the compressor should be on constantlyl at idle and his was cutting on/off every few seconds), I suspected a low refrigerant charge. As I was hooking up the gauges something moved me to feel the lines going into and out of the evaporatorl on the firewall. Normally the high side line (the small one) is warm or even hot and the larger suction line is cool. On this car, the high side is cold and the low side is warm, indicating a restriction. Haven't torn into it yet, but I expect to find a partially plugged orifice tube. Since the system is supposed to be sealed and surgically clean inside, the contamination is most likely from a broken dessicant bag in the accumulator or, worse, little bits of seal or whatever from the compressor. Should be interesting and educational.

On my '91 740 the AC would not come on at all with the switch, but running a jumper wire directly from the battery to the compressor produced cool air, indicating that the basic refrigeration system was good. Apparently the only fuse in the system is part of the AC control panel and replacing that with one from the junkyard was ultimately what fixed it. Here's that thread : https://volvoforums.com/forum/volvo-...-aircon-41960/

In my experience, it's hard to get a meaningful gauge reading if the compressor isn't coming on. I almost never get a "zero" reading when first putting gauges on a system, but that doesn't necessarily mean the system is "full". If the charge falls below a certain point, the low pressure switch on the accumulator will keep the compressor from coming on. I'd try running a jumper wire directly to the compressor. Let it run for a few seconds, then feel the accumulator. If it feels like it's starting to get cold, you probably have an electrical problem like I had on my 740.