Auto Air Conditioning & Heater Repair: A/C system is low and will be disconnected., buick riviera, side switch

Question
I have a 1988 Buick Riviera and on start up the display module says the a/c system is very low and wil be disengaged to save the compressor. Today I checked the a/c pressures and there was refigerant. I then jumped the a/c relay and the pressures were:
40  low side
200 high side

I would think that would be enough to turn it on, right?

Then I checked the low side switch and it was recieving power and sending power out. There were two switches in the high side line, but neither were recieving power.
Now What?

Thanks,

Mark

Answer
Located on the accumulator (receiver/drier) there is a 2 wire electrical switch called the PRESSURE CYCLING SWITCH. Disconnect this electrical switch and one terminal should have battery voltage within the connector. Jumper the 2 wires together in the connector and see if the compressor engages. If it does, you either have:


1. A faulty PRESSURE CYCLING SWITCH. This switch is known to fail.

2. Low freon in the system.