1997 3.0L A/C Electrical Problems

[desmarkus]

I just bought a 1997 caravan, 3.0L V6. The A/C wasn't working. So I checked it out and the Compressor was seized. So today I (along with a mechanic friend with his HVAC licence) replaced the compressor and clutch assembly topped with oil and recharged. NO leaks, lots of pressure. A/C clutch won't kick on. So we switch the Horn relay with the a/c clutch relay, nothing.

Then we just jumped the A/C clutch relay and the clutch would engage. So we tried putting the relay back in and jumping the safety pressure switch and the switch and nothing. Plugged the switch back in and jumped the temperature switch (behind the glove box) still nothing.

The A/C button lights up... Anybody know what could be the problem? Oh when we jump the relay to kick on the clutch the rad fan's don't start like they should. (But they do operate to control temperature)

I am stumped... the safety pressure switch doesn't seem to be the problem, the relay was working, could the a/c dash switch be lighting up but not telling the relay to engage the clutch? Do I have bigger problems? Check engine light has been lit since I bought it but I haven't retrieved the codes... maybe something to do with the A/C (or NOT)

Please Help

[desmarkus]

So after doing some more electical research and trouble shooting I have decided that perhaps the problem lies in the Computer. The a/c switch on the dash is working and sending a signal from the switch to the computer.

Without proper schematics I can't figure out where the applies power to the A/C relay to engage the clutch and start air conditioning. But I am assuming That the computer isn't sending power to the relay.

Has anyone heard of this type of PCM problem with the caravans?

Does anyone no an average price for a pcm lets say new or from a wrecker?

[bcstr1]

I am having the exact same problem. But have not figured out the solution yet.

[B33p3r]

Looking at schematics for a 2001, your relay signal originates from the ignition switch and then travels to the front control module, then to the relay. It looks like the PCM supplies the ground. So if you don't measure any voltage at the main coil of the relay look to the FCM and ignition. If you measure the voltage at the main coil, jump the ground side of relay to a known good ground. If that takes care of it, look for a broken wire on the ground side of relay or a PCM issue. PCM issue could be an input sensor, but it sounds like you jumped them already.