aircon on a xc70 and a v70 cross country

Hi Peter,

I had the identical problem on my 850, the "pressostat" pressure switch which controls the compressor clutch operation became heat sensitve. When cold it worked fine, but if the car was stopped, it wouldn't work again. Turned out the refigerant was keeping it cool so long as it was working, but when turned off, the rising heat from the exhaust manifold, directly below heated it and it failed. When the car was left long enough and it cooled down, the a/c worked again.

The good part is the switch is a screw on device with a "schrader" type valve on the plumbing which prevents any gas loss when changing. The bad part is the new switch cost about AUD120 about 5 years ago.

Changing the switch fixed the problem.

You can confirm this by removing plug on the switch and shorting out both pins (on the plug wiring - a paper clip works well) and the compressor should start.

BTW, I had three problems one after the other, first the evaporator finally gave up and needed to be replaced (a known problem, it was 10 years old by then), then the temperature cut out on the compressor failed, which is very simple to by-pass (seems they fail more often than the compressor) then the pressostat switch. All within a month. Then it was fine for the next 5 years, 'til I sold it.

Regards Barry

If you look at the A/C pipes immediately after you stop and see ice on them, then the system is probably overcharged.

If it is over pressured then the system cools down too much and freezes up, Exactly the same symptoms as a failed pressostat.

If it has happened on both cars, I suspect that you have recently had the systems recharged, and not by a Volvo dealer.

Exactly the same thing happened to me after I had a recharge at Halfords. After much headscrarching and changing of parts, I just let some gas out, and the system works fine now. I had the benefit of having one of those pressure gauges that come with the do it yourself charging kits.

Hope this helps. Rick... (The other Rick)

then the system is

Exactly the same

systems recharged, and not

After much headscrarching

I had the benefit of

Overcharging is unlikely, we haven't had the cars in except for regular service and some irregular repairs at the local ford shop which has the service agency for volvo. I can't imagine those guys fiddling with the aircon and not even telling us or charging us. (they charge like a wounded bull, I expect I'd _know_).

Still, I'll keep that in mind also as we try to find the source of the problems, thanks for the input.

-P.

then the system is

Exactly the same

systems recharged, and not

After much headscrarching

now. I had the benefit of

Ah Hah.. I suspect the A/C pump needs re-shimming See

then the system is

Exactly the same

systems recharged, and not

After much headscrarching

now. I had the benefit of

See attachment Rick... (The other Rick)