A/C help

After 190K on '97 Villager, had slightly used engine installed. It's running great - but the A/C compressor will not shut off. Pushing the off button on the control panel only closes the inside vents so no cold air flows, however the compressor continues to run and A/C components freeze up. A/C blows COLD air inside until it freezes. So, I can't turn off the A/C and the compressor won't cycle off. I'm having to disconnect at the compressor so I can drive the van without damaging A/C. Any ideas as to what is going on?

Russell

After 190K on '97 Villager, had slightly used engine installed. It's running great - but the A/C compressor will not shut off. Pushing the off button on the control panel only closes the inside vents so no cold air flows, however the compressor continues to run and A/C components freeze up. A/C blows COLD air inside until it freezes. So, I can't turn off the A/C and the compressor won't cycle off. I'm having to disconnect at the compressor so I can drive the van without damaging A/C. Any ideas as to what is going on?

Russell
3 possibilities, low pressure switch, high pressure switch, or control panel. In your case sounds like the control panel since when you turn a/c off at the control, it wont shut off the comppressor...........the low and high pressure switch only cycle the compressor, if, there is a command from the panel.......

Guess 1) There is an AC relay under the hood. Maybe it is frozen closed. There are identical relays around it (same color, same numbers). Switch it out with one of the others and see if it helps.

Guess 2) My compressor clutch froze in the off position. Maybe it's possible to freeze in the on position. To check if the clutch is working, pull the electric plug from the clutch (on the compressor). It should stop. If it is no good, you can get a used compressor/clutch for a few dollars off of a crashed car at www.car-part.com.

Thanks for the input. I pulled the relay for the a/c located under the hood inside the right fender. Looks like a capacitor switch. I ran a continuity check and it checked out okay. I reinstalled relay and I was then able to cut a/c off and on, but compressor wouldn't cycle. I bought a pressure switch that sits on dryer for $20 and all works fine so far. You guys may have been right - the relay may have been locked in the closed position - maybe by pulling the relay it allowed the capacitor in the switch to discharge and bring it back to working. I'll need to watch it as it may do the same again. Thanks again for the advice.