Hello all, sorry to start with a cry for help, but on the other hand I'm on my seventh Volvo estate and may have help to offer in future, usually of the 'make do and mend' variety.

Anyway, my 940 1997 P Classic LPT Aircon won't switch on. There was a time when I could hear a relay clicking on and off. Have I got a failed relay, and where is it? The local dealer said it would be 'somewhere on the front nearside' with a wave of the hand, and that the part number ends in 933.

 

Not necessarily an electrical problem; system will shut down if refrigerant charge leaks out. Try running a jumper wire directly to the compressor.
This should make it come on and you can feel the accumulator and see if it feels cold. If it doesn't, refrigeration problem. BTW, when you do this you are forcing the compressor to run even if there is no refrigerant in the system and if that is the case it will only be running on residual oil since the oil circulates with the refrigerant. If the accumulator doesn't get cold pretty quickly, disconnect the jumper wire.

 

Thanks. If it is a refrigerant problem, would there still be any evidence, sound from a relay for instance, when I push the switch?

 

No, when the low pressure switch deactivates the system to save the compressor it is breaking the electrical connection, so, no sound. I don't recall ever hearing a "relay" sound anyhow; the only sound I ever noticed on my 740 is from the compressor coming on.

BTW, I feel your pain. My own AC is also not coming on as it should. I have been unable to locate an AC relay, even after consulting with two dealers and an independent shop. Older models - mine's a '91 - have a relay located behind the glove box in the vicinity of the blower motor, but mine does not. In an earlier thread, a member found a bad connection on the back of his AC control panel which is the next thing I'm going to check. In the meantime I have done the test I described earlier and satisfied myself that I do have an electrical problem, which is step #1.

For the moment, I'm turning the system off and on with a jumper wire to the battery. In Texas, where I live, the AC is the life support system, so even though it's kind of a nuisance, it beats sweating.

I should mention that the jumper wire hookup I am using to temporarily stay cool is slightly different than what I described earlier for test purposes. If you leave the jumper wire hooked directly to the compressor it will run continuously, regardless of pressures, since you are essentially bypassing all the switches and safeguards, and this could cause evaporator freezing, excessive head pressure and other badness.

Let us know how you're coming with it..

 

Hi there, on my case even if I bypass the low pressure switch the compressor won't start. Compressor works if i jump it with a wire straight from the battery, I have pressure in the system. I would apreciate any kind of help solving yhis matter.