Hi folks - I have a 1998 S70 with about 165,000 miles. I've had the freon charged up, and the AC blows nice and cold forroughly 30-45 minutes, it varies, but after a period like this,the refrigeration stops refrigerating, and itjust blows ambient temperature air. If I then "let it rest" for another half hour or so while continuing driving (on a longer trip), then it will usually come back up again for awhile, before later again blowing ambient temperature air.

I realize it may not be possible to give a definite cause, but can anyone tell me a most common/most likely cause? It seems to me that it has adequate coolant, and the compressor is at least *capable* of functioning - if these things weren't true it couldn't get cold at all.

But perhapsthe compressorcuts out due to a sensor/switch issue, or perhaps something else? I will freely admit I don't understand real well what all the parts do in an A/C system, and appreciate any help from people who might know what usually is wrong with this model/year in such cases... Thanks!

 

I will bet the compressor clutch needs to be reshimmed.

 

Thanks Tech - I found your sticky on shimming this now:
https://volvoforums.com/m.asp?m=3443...page=1&key=

I looked a little under the hood of my car to see what I think we're talking about. There is a plate mounted outside of the pulley on the compressor.

If I understand you correctly, to verify that this is the cause, I can leave everything in place and try to slide a feeler gauge between the outside plate and the pulley, and find the largest size gauge that fits. If that size is > 0.020", then it needs to have some shim material removed to bring the two closer, so the clutch surfaces will stay engaged under torque, yes? Is it possible to check it in place like this?

 

Any freezing up?
(You can see it blow out of the vents)

 

The spec os .025 but I will also bet your will be at about .030 or .035.
Another way to verify 100% if you want to is drive it till it messes up. Then check and see if the compressor is not locked in. If you still have power and the center of the compressor isn't spinning with the motor running it needs to be reshimmed. If you want to take it one more step carefully tap the center part carefully and quickly and see if it starts spinning again.

 

If you mean like frost coming out of the vents, no, none of that...