Dear fellow "Brickboarders":

My A/C system works only intermittently (as outlined below). What are your thoughts / advice if my system charge is accurate, and there are no leaks? Symptoms outlined below:


My thoughts are that it must have something to do with the "ambient pressure", and the system's interpretation of that pressure. This is because of a) my system is properly charged, b) there is no leak, c) it cools properly and constantly when the outside temperature is below 75 degrees----approximately. Once the outside temperature climbs beyond that, I begin to notice the problem; and, the problem appears to escalate as the outside temperature increases. I also notice that if I turn off the a/c switch and leave it off for some time, then turn it back on, it will begin to cool again, but only for a short time until the problem repeats itself.

From what I've been able to gather, the problem would be with either 1) the pressostat / low pressure switch, 2) the high-pressure switch (Volvo refers to it as a MAPP sensor?), or 3) the compressor itself. NOTE: I've already checked the pressostat, so that leaves 2 or 3. Which is it? Or, is it something else altogether?

FYI: I've been told by one Volvo shop that it could well be the compressor, as the compressors that were installed in my particular model / year were notorious for this issue. the shop said that this compressor would exhibit this problem because once the clutch cycled "off", it wouldn't re-engage / turn back on.

Lastly, if it IS the compressor, do I HAVE to drain the coolant and remove the radiator----as the service manual says, or is there an easier way?


Thanks so much,

Sweating in Virginia

I also have a 1995 850 sedan, and am experiencing the exact same problem as you are. Intermitent A/C failure at higher temparatures, which gets worse as the temps climb. Obviously this is a serious problem because the hotter it is outside, the MORE I want A/C especially now that temps are over 100.

I'd appreciate any information you've found on the subject, and I'll be glad to compare notes with you and let you know how my problems are progressing. I'm not a gear head, and I really don't know much about the nuts and bolts of the operation but if you want me to test anything out on my system to try to solve the problem feel free to ask me.

Sweating in Vancouver. Yes it gets hot in Vancouver.

Well, a fellow member gave me some good advice. He said to pull the car over the next time the a/c stopped, and check to see if the clutch was running. If it wasn't, then to carefully take something (I used a socket extension bar) to "nudge" the clutch inwards. If it caught, then there is too much "play" in the compressor/clutch, so removing a spacer would fix it. Guess what? That was exactly what happened in my case. As soon as I pushed the clutch in, it caught, and began cooling again----albeit for only a few minutes. This tells me that it IS in fact the compressor, rather than some sensor/switch issue. (I haven't decided yet whether to dissassemble the compressor and remove the spacer, or simply replace the whole compressor.)

Sweating in Virginia

Mine was doing that for 2 or 3 yrs. I finally broke down and had the compressor replaced a couple of months ago. (about $650 at an indy) If you replace just the clutch it is likely that the compressor will go soon anyway.

I had the evaporator done last year...cost about double that when it leaked so badly that wouldn't hold a charge anymore..

If you are handy and can do the spacer thing...I'd do it...you might gain some time before replacing the whole thing.

Lucy
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'95 854T 135,000

Sounds like the clutch to me. You can look at the clutch and see if it is working when you think it should be.

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Howard Berman 95 850 wagon 155K 95 850 Sedan 140K, 94 850 Sedan Turbo 140K, 68 1800S 80K(My Toy)