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Air Cond - 96 850

Hi,

I have reason to believe the air conditioner low pressure "pressostat" switch is intermittently faulty in my 96 Volvo 850. It is a non-climate control system. It has the correct charge (750g) and a gauge on the low pressure side seems to point to the switch being bad. The symptom is that sometimes the a/c will cool properly, 3deg C from the vents, with outside 33 deg, and other times the compressor will only stay on for perhaps one second, and of course not cool at all. One instance of this, with the pressostat plug s/c, the compressor would start and with ambient over 40deg C, 15 deg C from the vents, and the suction line to the compressor is sweating but not freezing. With the pressostat in circuit, compressor short cycling. Drive 15 km, turn on and then its all working ok again.

My question is: Is there a (shrader type) valve under the pressostat switch which allows it to be replaced without de-gassing the system? Can anyone tell me for sure?

By the way, the evaporator has recently been replaced and this seems to be (unfortunately) an unrelated problem.

Regards Barry

Reply to
Baz
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There is a (shrader type) valve under the pressostat switch. If you had a pressure gauge on the low side, you should see the pressostat cutting the compressor out in the range of 23-25 psi.

Reply to
Mike F

Thanks , Mike, that's what I was hoping to hear. The pressostat control is intermittent. When it works the pressure is correct. When it's playing up, the compressor clicks in and out almost instantly. With it replaced by a short circuit, the pressure is as expected. I still have to convince myself it's not the connector pins having been spread and causing a bad connection etc, but I can now replace the switch if that's needed without worrying about opening the system, which is an additional hassle I didn't want.

Thanks, Barry

Reply to
Baz

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