I have a wierd (at least it seems wierd to me) problem with my A/C on a 850 with 244,000 miles and in otherwise good working order. During the summer -- when it is needed the most -- the A/C will not run consistently. It will blow cold for five, 10 sometimes as long as 30 minutes and then stop cooling. If you turn off the A/C for five minutes or so and turn it back on it will be cold again for a little while and then stop working again. It only seems to happen when I'm driving and the coolant level is in the "good" zone of the pressure gauge I bought to check on that. The thing that really boggles my mind is that on a recent rainy day when the temperature was not as hot, but I needed the A/C to dehumidfy the car, it worked for my entire 60 minute drive home.

Does anyone have any ideas as to what may be wrong? None of the repair shops I call will even guess as to what may be wrong and I don't want to take it in until I know whether it may be something as small as a bad pressure switch or as big as the compressor going out. I'd appreciate any advice and/or stories relating to similar situations.

Jim

This thread may be too old but I had another thought that I wanted to add.
B/C my a/c clutch was struggling, I always made sure that my a/c charge was "high-normal."
Then, it occurred to me . . . I released enough refrigerant to make it "low-normal." The temp inside the center duct was still around 39-40F. That change helped my a/c a LOT b/c it allowed the low pressure switch to do its job (and MORE importantly for my tired ol' compressor, it allowed it to rest several seconds when it cycled off).
Another huge help for my "rest theory" is to run the a/c only on the Fan Setting = 1. Try it.

I've had this too with my Texas-based 1996 850. However, my fix has been to top off the freon/coolant. I've do it about every 4 years. Did I mention it was 102 degrees yesterday? Ben

I will have to agree that it is the clutch gap being too wide. As much as the AC is used, the clutch will wear and the gap increases. Heat will rob the compressor of needed electrical power to pull in the clutch, and if the gap is too far, it will not kick in.
That is the next step in my 1995. The 1998 just has a leaky evaporator!

Klaus
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(V♂LV♂s 1995 854T, 1998 V70R)

You can test if it is the clutch with a volt meter connected to the clutch wire. I ran a wire into the pass seat and listened to the meter when it got voltage and did not get cool I knew the clutch was not working right. Also noticed the voltage was only 11.0 at the clutch wire. I put a relay into the circuit direct from the battery and it has been working great for many weeks now. The car stays cool in stop and go traffic, like it should.

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

I wrestled w/ this exact problem for many months w/ my 95 850. Here's my summary (more later when I have a few minutes, if you still have ?'s). Assumming you have the manual climate control . . .

1) Easy enough to bypass that "superheat switch" on the back of the compressor, but I've never heard of any example when it actually solved the problem (I'm sure it has for some but appears to be unlikely).
2) Need to determine if power is getting to the compressor when it's not working (rules out all the switches/relays). Easiest quick check to me is to wait until it stops working.
Note how the a/c clutch (on pass. side of compressor) stops spinning (as it always does w/ compressor off). Somehow tap on that round metal plate when the a/c is on and compressor NOT working. Be careful b/c of the aux. belt! (Not in the ASE mechanic book of smart things to try.) My bet is that it will immediately kick in and work.
3) If that answers the problem, then it's on to the a/c clutch problem. Many will say to just replace the compressor at this pt b/c it's "not far behind." If you have $500 (rebuilt aftermarket), I'd go w/ that. If not, time to try and "re-shim" the a/c clutch.
Hope this helps! Thad

Thanks, Thad and Klaus. I will check all of the switch and electrical first and if that fails to solve anything I'll try my best to "test" the clutch. I"ll be sure to post what I find out.

Jim

Klaus may be right, but could also be AC compressor clutch.

There should be a temperature switch on top of the compressor. bypass it. It should look like 2 wires going to the compressor, into a black box, then to a resistor before going into the compressor. Have the wires go directly to the resistor. This should keep the compressor from thinking it is over heating.

If this works, let me know! The rain might have kept the engine temp down.

Klaus
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(V♂LV♂s 1995 854T, 1998 V70R)

Klaus,

You're definitely a Volvo 850 expert and I value your opinion. I'm having the same problem with my A/C with intermittent cooling in warm temps. This problem just started this summer and I'm not sure exactly where to start. Keep in mind, I am NOT a gear-head and I do not know how to fix things myself but I am willing to listen to information and take it in to my mechanic. I usually tell him what I think the problem is and set him loose on it, I'd say the majority of the time after talking with you guys on BB, when I have him fix something it always repairs at least one of the symptoms.

Anyhow, to make a long story short my air conditioner is not functioning now and I honestly don't know what to make of it. I see people talking about an A/C clutch - I don't know what that is, where it is, or what it does. Consider me clueless but always ready to learn more.

Thanks,
David

LOL

Thank's Blue, but I am hardly an EXPERT! I just learned a little over the last 3 years, just enough to make myself dangerous.
First, get a manual or go to the library and look for an 850 Volvo manual. Copy a couple of pages with engine pics and locations or parts with labels. This is not rocket science and your engine is almost fool proof.
The AC compressor is on the front of the engine, the right side of the car, and down below the alternator. Very hard to see without a flash light. The clutch for the compressor is the part that sometimes spins around. When the clutch is not turning, the compressor is not working. Simple.
Read all of the posts for 850 and 70 series cars. Some of them are relevant.

Klaus
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(V♂LV♂s 1995 854T, 1998 V70R)