After starting up my 850 turbo, all seems fine with the AC, but after 30-45 minutes driving, it starts putting out hot air. Eventually, it'll cool off again, and if I turn the car off for a couple hours, it will work fine when I restart.

Last week I bought a combo r-134 and pressure gauge. I got 45 psi, at the high end of normal with the engine warm and running, AC cranked up all the way.

Later that week, I was pulling into my driveway with the AC blowing hot. Checked the pressure and it was at 100+. Scary.

Today, I started the car and hooked up the pressure gauge. Got 45 psi. Let it run for a little while and pressure started rising till it was at 55 psi, in the middle of the "alert" range. Turned on the recirculate button on the climate control, and the pressure went back down to 40-45 range. Lather, rinse, repeat with same results.If recirc is on, pressure in the 40-45 range, turn recirc off and watch it climb to 55 in about 15 seconds, then recirc on and it falls again.

All the while it's putting out cold air. I can never seem to duplicate a problem when I have tools and time to do something about it,.

Drove around for 40 minutes and continued to get cool air with the recirc set on.

The compressor will engage and disengage when I swith the AC from "off" to "aut" but doesn't seem to cycle a whole lot otherwise.

Both pipes that head into the firewall are cold. Very cold.

Thoughts, ideas, suggestions?

Bueller?

Bueller?

If you need more information, I'll try to answer to the best of my ability.

Todd
affirmed(at)mindspring.com

Today I had the problem where my AC stopped putting out cold air, although using recirc liberally did appear to help.

When it started blowing hot, I pulled into the next gas station, popped the hood and hooked up the pressure gauge and got 100 psi. Holy cow.

At this point, both pipes going into the firewall were warm to the touch.

Any thought, suggestions, etc?

Thanks.

todd

When the compressor is not cycling the pressure in the system will approach 100psi in hot weather. That is the natural pressure of condenced R134. AS it cools the tempreture drops. When the compressor is cycling you are measuring the low (intake) side of system. Somewhere I saw a chart plotting temp vs. pressure for R134. You might find it on the net.
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Tom 69-1800S, 72-1800ES, 96-850T,2000-S70 GLT-SE

Todd,
I hope you are watching my post also. The heat broke today, it's in the mid 70's, and the ac works just fine. There isn't enough air flowing through the condenser to cool the r134a, and even though the compressor runs the gasses are too hot to cool off at the evaporator.
I am trying to figure out how to help my 850T cool itself off. When I find out how, I will post a new thread.

Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)

If you do a search on this site, or just look down the paqge, you will find a zillion of us with the same problem.

Generally, it is probably the clutch in the compressor that is worn out and not engaging. It is recommended to replace the whole compressor, not just the clutch.
Some have removed a spacer between the clutch and the compressor.

You can read what others have tried and done.

There are a/c temp sensors at the grab handles above the front doors. (Little circles with a line through them. Some have tried cleaning those.

I turn mine off at long red lights because on on accelleration it tends to blow warm. Then I can just turn it off for several minutes then on and ot willl work again.

If you haven't yet replaced the evaporator then that is usually the first A/C part to go. Will start leaking so badly that it eventualy won't work at all with a new recharge. It goes from 2 months recharge, down to a month, the two weeks, then not at all. None of it is cheap. If you are willing to remove your whole dash yourelf there are detailed instructions on a couple of sites with various links around here. www.volvo-forums.com keeps one on top of their 850 section.
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'95 854T 125,000

I basically have the same problem with my V70 and as of this morning it was in at my indie to take a look at (not the first time on this problem). They are seeing quite a few cars here locally with the same problem and claim that that the fix is a new compressor. Actually, just as mentioned its not the compressor but the clutch. Personally, I think the fix is bogus but try and find the clutch assembly as a seperate bit! Anyway, I thought that I would just add my two cents in here as a kind of confirmation that the fix seems to be a new compressor (i.e. clutch).

Cheers,

If it appeared that my problem was the same as those experienced by others on the board, I wouldn't have started a new thread. I did indeed search through this forum and read every single post that appeared to be on point.

The main difference I see between my problem and the vast majority of the similar problems that have been reported here is that mine does not seem to be an issue of low pressure.

I didn't read of a case of _elevated_ pressure in any other posts, which is what I thought made it worth posting as a new question.

The lowest I have seen when measuring the pressure is roughly 40 psi. I have also seen over 100 psi, which is quite alarming to me.

It's also possible that the inexpensive/free with purchase of a large can of refrigerant gauge is inaccurate. I'll try to get another one of another brand and see what I turn up.