A/C Clutch Not Engaging. Need help.

sneaky98gt · Jun 4, 2010

This started yesterday afternoon. I drove for about an hour and half from home to school (with the AC on, like I always do), parked at my apartment, came back to my car an hour later, and the AC wasn't working. I got out and the pulley is spinning, but the clutch is not kicking on, although I can still spin it freely with my hand. The plug into the AC appears to be fine. Fuse is also fine. Because it was still blowing cold when I got out of the car, I think the R134 is fine, but I could be wrong. My dad said that there is probably a pressure switch that will not allow it to come on if it is too high or too low. I'm going to get him to check it tomorrow afternoon (he has gauges and vacuum pump and all that), but I have about 4 hours of driving to do between this afternoon and tomorrow, and it's about 95 up here.

Any ideas on what's causing this?

trombonedemon · Jun 4, 2010

sneaky98gt said:
This started yesterday afternoon. I drove for about an hour and half from home to school (with the AC on, like I always do), parked at my apartment, came back to my car an hour later, and the AC wasn't working. I got out and the pulley is spinning, but the clutch is not kicking on, although I can still spin it freely with my hand. The plug into the AC appears to be fine. Fuse is also fine. Because it was still blowing cold when I got out of the car, I think the R134 is fine, but I could be wrong. My dad said that there is probably a pressure switch that will not allow it to come on if it is too high or too low. I'm going to get him to check it tomorrow afternoon (he has gauges and vacuum pump and all that), but I have about 4 hours of driving to do between this afternoon and tomorrow, and it's about 95 up here.

Any ideas on what's causing this?

Heres a trick my teacher taught me, to engage the pressure switch, take the switch out, and take a paper clip and stick in both holes to complete a circuit. See if the pressure switch comes on. If the switch dosn't come on then you know its the switch. When the switch comes on, put the switch back after turning the A/C off then back on and listen for the switch to engage, if the switch does not engage then you know you have a High Low pressure problem. Report back w/your results.

sneaky98gt · Jun 6, 2010

trombonedemon said:
Heres a trick my teacher taught me, to engage the pressure switch, take the switch out, and take a paper clip and stick in both holes to complete a circuit. See if the pressure switch comes on. If the switch dosn't come on then you know its the switch. When the switch comes on, put the switch back after turning the A/C off then back on and listen for the switch to engage, if the switch does not engage then you know you have a High Low pressure problem. Report back w/your results.

Pressures were fine; checked the low pressure switch like you said and it was fine too; there is no voltage getting to the clutch, so that means that it's electrical and not mechanical.

We need a AC wiring diagram. Anyone got a link to one?

Edit: Got a wiring diagram.

sneaky98gt · Jun 6, 2010

We have power all the way to the wire coming off the clutch cycling switch going to the CCRM.

Where is the CCRM?

wmburns · Jun 6, 2010

Assuming the fuses are OK (all of them!).

Confirm if +12 volts sent to AC clutch the clutch will engage.

Check the DG/O wire at the CCRM for +12 volts with the AC on. If not, the problem is upstream of the CCRM.

Monitor the PCM operating status with an ODB2. Look at the AC clutch PID to confirm that the PCM is calling for AC. If yes, then the CCRM is BAD.

If not, the problem is in the AC controls in the dash (in any case, more trouble shooting will be necessary).

My $$ is on a bad CCRM. The CCRM is located in right hand fender well. Remove the fender liner for access.

sneaky98gt · Jun 6, 2010

We have voltage all the way to the CCRM.

We don't have a scanner that will monitor the PCM. Is there any other way to confirm or not if the CCRM is bad?

sneaky98gt · Jun 6, 2010

It was the CCRM, or well, the relay in the CCRM that controls the air conditioner clutch. There was a bad solder joint. We soldered up that joint and put it back together and the AC went back to working. I'll get some pictures up in a bit.

StangSims39 · Jun 6, 2010

Nice! glad you got that workin, its hot as balls outside!

sneaky98gt · Jun 6, 2010

Dang. It has already quit again. It lasted until the car got driven for about 15 miles. My dad (a certified electrician) said that he was pretty sure that the relay inside the CCRM was bad, or at least the leads inside of it were burnt up. The side of the relay appeared to have gotten really hot at some point. So once it was on for a while, and warmed up, it just gave way again.

I've read that you can replace that relay, but it seems that that doesn't last long either. So I guess I'm going to have to get a new CCRM.

Question now is do I get a new one? Or a junkyard/reman one? I'm going to the dealer tomorrow to get a price on one. I'll probably let that decide for me.

wmburns · Jun 6, 2010

If it were me, I would go new (re-man).

Cardone 73-70020 - Relay Control Module | O'Reilly Auto Parts

Amazon.com: A1 Cardone 73-70020 Relay Control Module: Automotive

Of course it's not a bad idea to check prices at the junk yard.

A/C Clutch Not Engaging. Need help.

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