After checking al the other possible solutions, I have determined that the AC relay in my wifes 850 is bad.

How do I know this? Well.. basically.. everytime the relay gets hot, the compressor will not kick on.

I know about the shimming, etc. The Compressor will kick on just fine with direct connection to the battery, so it is within gap specs. It is obviously not receving enough juice from the relay to get the magnetism to engage the clutch.

While I am on this subject, I know that the system might be a little low on freon, but after re-seating the compressor (the blue one behind the glove box) the compressor instantly kicked on... getting REALLY HOT in the process.

So - are there any "mo better" AC relays for an 850? Aftermarket ones? The one that I pulled from the system doesn't look fit to handle a light bulb for a long period of time. It is the typical blue capped, Volvo and Hella stamped, 4RD 003 520-52, Made in Spain Relay.

Thanks in advance!

 

I was trolling around, and saw this part:
Relay. Hardware Part for Volvo (9130270)

this matches a Volvo number that is on the relay - anyone know if this would work? Seems like its the same thing as they describe it as a "blue capped" relay, but they say that it is for fog lamps...???

There was also this one, that had the desciption of: "Relay with resistance A.C W/O A.C (9130270) (9162250)" in the exploded AC Unit view."
Heater unit e. C. C e. C. C, L. H. D. Fits: Volvo | VolvoPartsWebstore.com

Relay. Hardware Part for Volvo (9494787)

 

Have you tried jumping the pressure switch to see if it will run on its own?

If the relay does turn out to be bad I see no reason to go out and try to rig another type of relay in there. The OEM relay is fine, get another new or from a wrecker and move on.

If the system is indeed trying to run, sending voltage to the compressor but the clutch does not quite engage then let that trigger wire feed an aftermarket relay that gets its power directly from the battery.

 

Box - I will get the OEM relay to put behind the glove box and go from there.

 

Ok - according to the guys Volvo Parts Web Store - this

http://www.volvopartswebstore.com/products/Relay/1196400/9494787.html

IS a direct replacement for the 9130270 (aka Hella 4RD 003 520-52) -

Gonna order it, and see what happens.