2002 Dodge Grand Caravan Sport, 3.3L, front and rear manual heater controls. Had an AC leak and the compressor had disengaged due to lack of pressure while the AC climate control button was still on. Leak fixed, AC working perfectly, but now any time the van is to be started, the Climate Control Power button is always on even if you set it to off before shutting off the van previously and the AC button is always on as well. What then happens is when you try to start the van, the AC compressor tries to engage as the van is starting, causing loud horrible noises which I fear one day will break the compressor. Even if you turn the van key to ON, then turn AC button from on to off (or power button from on to off), then start the van, the AC and power button is back on again right away during starting. Button works fine as long as the van is running... you can turn it on and off without problems. Shut off the van completely, go to restart it and back to the original problem - AC button on, compressor tries to engage during starting. Compressor doesn't wait for the engine to be running to engage. Is there a way to reset the AC button so that it is OFF when you start the van? Because as of now, it is always in the on position every time the van is started.

I can't seem to find an answer anywhere.

 

What was done to fix the leak? The A/C button isn't physically sticking correct? Only way to "reset" it is to disconnect the battery for 5 minutes. This resets the HVAC processor in the control panel. That or it may have to be reprogrammed at a dealership. Might try a calibration procedure. It's in the Tizzy and others DIY information "sticky" at the top of the forum.

 

Thanks for replying. Front condenser had a small crack in it causing a slow leak, and it was replaced. AC works fine and blows cold, and the ac on/off button does work no problem, except it is always "on" when starting.

Only calibration I found was the power + recirc buttons for five seconds. The Depress WASH and REAR WIPER button simultaneously method does not work for me, because the buttons aren't off to the left, they are on the top (as shown in this image I found through Google Images - http://www.autodetective.com/_upload...003/580307.jpg - I don't have the tape deck, but the HVAC and wiper controls are identical).

Doing the only calibration test I found, AND having the battery disconnected for over an hour - didn't change a thing. Power and AC buttons default to ON when starting the van, causing the AC to engage even before the van is fully started.

 

Swap the A/C Clutch Relay in the PDC with one of the other relays. If it doesn't change the symptom. remove the relay and see if the A/C still starts when the engine starts.
Just a thought, does the A/C clutch engage when you turn the key on, or when you turn it to start?

 

1. Key inserted, but not turned - no power, obviously.

2. Key turned to ON, but no engine - hvac power light and ac lights are on.

3. Key turned to start engine - lights go out briefly, but both come back on and before engine is fully started, ac is engaging.

Between 2 and 3, if I manually turn off hvac power and ac buttons, #3 still happens.

Disconnected battery for an overnight, no difference.

Swapped relay with one for fog lamps, no difference.

Removed relay completely, hvac power on and blowing, ac button on, but no ac and no clutch engaging.

It seems to me (just through educated guessing) that hvac power and ac buttons should default to off on van start, but mine is defaulting to on... and I can't get it to really go off until after the van is started, but by then is too late because the clutch has already tried to engage and after a horrible noise (similar to but sounding different than grinding the gears on a manual transmission) ac fires up.

And once it does, I can turn it off and on no problem. Turn everything off, shut off the van, and as soon as I turn the key to on, #2 happens.

 

I'm looking for the wiring diagram for it. It's sounding like a bad electronic control module of some type.