2nd Gen Non-Engine/Transmission A/C cycle

[JRS]

After driving for about an hour if you rotate the temperature knob to the last two detents in the blue section (cold) section before the red section, the compressor will stop cycling and stay off. If you turn off the fan,wait about 5 seconds and turn it back on, everything works fine. The A/C compressor kicks in and starts blowing air at the warmer cold setting. It may work correctly for another hour (with the clutch cycling) or it may only work for another five minutes. Then you have to turn the fan off, wait 5 seconds and turn it back on. It only happens with the temperature knob turned to the last two detents in the blue section. Clutch relay? Maybe at the warmer setting makes the clutch cycle more? (showing a faulty relay) Changing the low pressure switch and high pressure switch in the freon circuit made no difference. Is there anything behind the temperature knob that maybe needs to be cleaned with contact spray? (reostat or wiper?)

 

[monkeyman]

Try unplugging the low pressure switch and crossing the wires, if compressor stays on, your low on freon or low pressure switch is bad. They are not the same. That year had a rash of bad evaporators, I had one.

Rick

 

[JRS]

It turned out to be the a/c clutch relay. Just would not hold up to high under hood heat after an hour or so. Seems there is a timer (resistor/capacitor) that keeps the relay coil from pulling in immediately upon twisting the key.