The AC on my 94 940 (non-turbo) just started acting up with what may be a malfunction of the pressostat. Once the compressor kicks in, everything is fine and cooling is excellent so I assume I have an adequate freon charge. (I haven't dragged the gauges out yet to check pressures.) However over the last couple of days, it has occassionally cut out - not welcome with our 100F temperatures in Texas. The first time it happened, it didn't cool during the first few minutes after sitting overnight but then worked fine. Last night, it worked periodically. This morning on the way to work, no problem.

If the problem is the pressostat, is this a binary device - either making an open or closed circuit? If that's the case, I would assume it is open with excessively low pressure and closed if the pressure is adequate on the suction side. If that is the way it works, I should be able to short the connections in the the connector when the problem manifests itself to see if the compressor clutch then engages. That would give me confidence that it is the pressostat malfunctioning. Is my logic correct?

Thanks,
Ron