A/C Problem

[Joe 1320]

Here's the scenerio......

93 Z28, the a/c is charged and blows cold. it works perfectly about 90% of the time. Sometimes the compressor cuts off and it will not kick back in unless the car is shut off and restarted. Again, the R134a is at the correct level. When this happens you can turn the a/c off and on as many times as you wish and it will not kick back on unless you shut off the engine and restart. It's done this for 2 years and normally it's not a real big deal.

Now my 94 V6 has started to show signs of this. Sometimes when you start the car, the a/c just won't energize the compressor clutch. Turning the a/c off and on again has no effect. Only shutting off the car and restarting clears the problem and everything works perfectly.

My thought is high heat switch, but why would nothing respond unless the motor is shut off and restarted?

[Jeff_in_Atl]

The first thing I would do is when it does it and won't turn on, unplug the compressor and put a volt meter on it to see if it is being commanded to turn on.
If it is, the A/C clutch is bad.
If it isn't start going backwards. Check to see if voltage is getting to the relay in the fuse panel.
If it still isn't getting voltage check the low pressure switch on the passanger side to see if power is going to it and through it.

[97LT1Z28]

Something else to check too......a buddy of mine had these problems caused by a bad ECM. His mechanic said that the ECM sends out commands to cut off the compressor under certain conditions (i.e. full throttle acceleration). His went bad and caused the AC to cut-off at random...... From what I understand, he replaced it and fixed the problem.

[zaino@cox.net]

Mine has done that since it was new. I have to remember to turn the ac off before the car. No one has ever given me a clue to why it happens but it is annoying!