Well I had a spare pressostat lying around and figured I'd replace it and see what the results would be regarding the intermittent quick cycling of the compressor. When I unscrewed it from the receiver/drier the freon starting coming out. Either the shrader valve is stuck or busted. Anyway I tried to screw it back in quickly and the o-ring unseated itself. So you could imagine me fumbling around trying not to lose anymore freon and getting another switch in. Anyway, probably about 30 seconds later got the other switch in and thought for sure it'd be blowing warm. Was surprised the a/c system still cools some but could tell, not as much as before so must not have lost too much. Ticks me off cause I just paid $120 to get it evac/recharged.

I'd hate to pay another $120 to do it over again. Is there a way to just top it off a bit or do I just bite the bullet?

Also if I get it evac/recharged again, do I have to pay for a complete refill of freon or does it get recycled and reused?

Thanks for input.

95' 964 164k

Nearly two years ago I had the same problem on a '94 945T. It was the pressostat. I bought TWO faulty switches from Volvo, until I finally found an aftermarket switch that worked.

It drove me crazy for days after I installed the first new BAD switch. Then I got anouther (2nd) switch and the compressor continued its rapid cycling.

I persisted that the switch was the only thing wrong with the system and found an aftermarket unit that worked. I was unable to convence the vendor that he had a batch of bad pressostats. They are costly, and NOBODY takes back electrical items.

Do this.......

Disconnect the leads from the pressostat and make a jumper to connect the leads together. Now see if the compressor stops the rapid cycling.

Just my experience, good luck.

Hello, Quick cycling sounds more like there is too much 134. Your pressure switch, high side may be turning the compressor on and off. Low 134 would generally be much slower. It would not turn on all together if it was your inside control panel.

Don't go looking for electrical troubles, as you will not find one. The on/off times are directly controlled by refrigerant pressure (on the low side) and highly dependent on cooling load. Low cooling needs = low compressor ON times. On a warm day or with the blower on high, the compressor should stay engaged for anywhere from 10 seconds to a few minutes before cycling off. Cool car, low fan speed will result in quick cycling.

However, if the fast cycling is happening with the blower on high speed, then either the system was undercharged or some refrigerant (it is R-134a, not Freon) has leaked out and will continue to do so.

Compressor cycling on and off in a regular pattern is normally a symptom of low freon. You will probably observe little or no cooling at the same time.
--
David Hunter

Dear dnice,

Good a.m. and may this find you well. If the aircon blows cold, there likely is not a freon leak.

The first thing to rule out is a failed solder connection in the controller. Once you have accessed the controller (see FAQs), you'll need to re-flow the solder on the relay's four pins (the relay is black pastic rectangular box, about 3/4"/20mm long). Then re-flow the solder on the main connector (12 pins, if I recall correctly).

If this does not solve the problem, the pressostat, located on the receiver/drier may be the problem. Current flows from the control unit, to the pressostat, and thence to the compressor.

Hope this helps.

Yours faithfully,

spook