Caravan (or any) A/C clutch diagnostics

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pishta

pishta

I know I'm right....
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My '12 Caravan compressor clutch is not engaging. I've got 110 psi in the A/C low side with motor off, I have 14V to the clutch harness (measuring red to 12+ and black to harness leads) and even motor off I have 7.57V (up from 0V after about 40 seconds of turning motor off and pulling the key) to clutch harness measuring its ground to battery +. What gives? Just a bad clutch? no engagement. Im not sure if this is always on (I had harness voltage with AC on and off) and the blend door handles the temperature? Any quick DMM reading on a good clutch, ie continuity on the 2 wires off the clutch coil?
 
is replacing the clutch coil an option? $29 on Rock......
 
I would check for continuity and then jumper 12V directly into it and see if it engages. Be careful to get polarity correct because many of them have a spike diode in the compressor pigtail, and you WILL blow that "shorted."

It should be a simple matter of 12V to the coil, but if you are not checking it under load, AKA say you are checking it with the connector separated, then there may be a "drop" problem in the wiring/ terminals/ switching.
 
So just 12V+ to green and ground to black inside connector? Can do, I'll have to release the clip of the plug to see in there. I should have continuity though, right? A coil is just that, an open loop.
 
On my brother's 07 caravan I kept hearing about the blower motor not working, over and over.
He finally brought it to me to check out and I ran jumpers right from the battery, motor worked. Went to blower resistor no power coming in. Swapped heater controls cuz I had another one here. It ended up being a problem with the under hood fuse box, went to junkyard and got another problem finally fixed. (Hey guys do you have a little brother that complains and complains and when he finally brings you his car to find out what's up he brings it over while it's raining?? Mine did)
 
volaredon said:
.... (Hey guys do you have a little brother that complains and complains and when he finally brings you his car to find out what's up he brings it over while it's raining?? Mine did)
Click to expand...
No, I got a 21 year old that refuses to roll down his window after I fixed the 3rd guide pin that had come out, causing the window to **** and bind. BTW he has no AC either so he's gonna be sweating unless he trusts me on that window now.

So I got a pigtail for that clutch harness at the junk yard and will test 12V in to see if this thing clicks. I hope it doesn't as that is a cheap fix. If it does cycle I'm F'd. R134 in California is like gold gas, priced the same.
 
pishta said:
So just 12V+ to green and ground to black inside connector? Can do, I'll have to release the clip of the plug to see in there. I should have continuity though, right? A coil is just that, an open loop.
Click to expand...
As I said, be careful of the spike diode. Use a meter to try and determine, or consult diagram. green vs black, don't assume one is ground

Also have you tried bypassing the low pressure switch? It COULD be bad, regardless of low side pressure
 
Sometimes, those pressure switches are adjustable. You can tell if they have a small flat blade screw in the center. It is a switch after all and they do go out of adjustment sometimes. I've gotten lucky a few times and turned that screw slightly and game on. Just another thought.
 
Yes: The only switch I found was on the high side up at the drier. Its a 3 pin so its not just a 'jump it' type of connection. I also read that you can't jump these 3 pins as it will damage the ECU that drives this system. So the test is put the whole plug in water (?) and sure enough, the fans started up but no compressor clutch. Weird test but I think the 5V supply voltage has to be reduced for the sense line, another said to back feed it 2.5V via a voltage drop resistor (2 150's across in series and you tap into the middle), the water seemed easier and it did trip the fans. Ill test when it gets a little lighter out. Good news is these compressors look to just unbolt and drop out the front, I saw a few at the junk yard and it looks like they can even be lowered a few inches with the lines attached to do whatever you need to do on them, ie. pressing the coil back onto the ring. Hope that is not impossible with hand tools under there. Last thing I want to have happen is lose the R134, its literally ~$12 for 12oz. with $10 on top of that to return the can.
 
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I watched a youtube video once where the guy pretty much knew where the problem was. He went through entire diagnosis to prove a failed harness connector down near the frame rail about 10 inches from compressor. Good luck
 
OK, clutch coil is BAD. 12V battery right to a harness pigtail plugged into coil, zilch. No click, clack spark or buzz. Now....anyone got a bad compressor from just about anything FCA laying around that they want to sell me the coil out of? These things are $150 alone!
CHRYSLER2002011-2014
CHRYSLER3002011-2013
CHRYSLERSEBRING2009-2010
CHRYSLERTOWN & COUNTRY2011-2014
DODGEAVENGER2009-2014
DODGECHALLENGER2011-2014
DODGECHARGER2011-2013
DODGEDAKOTA2004-2007
DODGEDURANGO2011-2014
DODGEGRAND CARAVAN2011-2014
DODGEJOURNEY2009-2014
DODGERAM 1500 PICKUP2009-2010
DODGERAM 2500 PICKUP2009-2010
JEEPGRAND CHEROKEE2011-2014
RAM15002011-2013
RAM25002011-2014
RAM35002013-2014
 
pishta said:
OK, clutch coil is BAD. 12V battery right to a harness pigtail plugged into coil, zilch. No click, clack spark or buzz. Now....anyone got a bad compressor from just about anything FCA laying around that they want to sell me the coil out of? These things are $150 alone!
CHRYSLER2002011-2014
CHRYSLER3002011-2013
CHRYSLERSEBRING2009-2010
CHRYSLERTOWN & COUNTRY2011-2014
DODGEAVENGER2009-2014
DODGECHALLENGER2011-2014
DODGECHARGER2011-2013
DODGEDAKOTA2004-2007
DODGEDURANGO2011-2014
DODGEGRAND CARAVAN2011-2014
DODGEJOURNEY2009-2014
DODGERAM 1500 PICKUP2009-2010
DODGERAM 2500 PICKUP2009-2010
JEEPGRAND CHEROKEE2011-2014
RAM15002011-2013
RAM25002011-2014
RAM35002013-2014
Click to expand...
What kinda compressor is it?
 
Mother F'r....right under the metal harness bracket. Not sure why the coil failed from this but I'm glad it didn't short the PCM that runs the show down here. No relay in this circuit ....if I read right. New coil energizes fine, clutch surface is a little glazed but that's for another time. That's an easy job as the clutch cover and pulley just slide off (?) after the weird circlip and belt is removed.. $18 for the entire clutch/pulley/coil at pick your part (F the warranty), just zip tie coil inside the pulley/clutch cover and tell them it's a unit as they don't list just the coil anymore.

20221029_092124.jpg
 
I think it shorted internally and burned here. Insulation was pretty crispy.
>>> Matter-of-fact, it was shorting the PCM system. We were getting intermittent A/C indicator (not a low signal) as well as hi-lo blend button. All lights stable now.<<<
 
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I agree with your analysis. Must have been an internal short to ground to draw enough current to melt the wire insulation. When I bought my 1982 Dodge Aries from a sister's friend, I found the AC clutch didn't engage. Some friend, they never told me that, nor that the water-pump leaked (was raining), and the alternator didn't charge the battery. After buying a new clutch w/ coil ($100 auto parts), I found the only problem was a bad ground where clutch coil- screwed into the compressor body, which a little sanding fixed. Got a refund on the new coil since not installed. Even with a good coil and supply, they don't always engage if the plate gap is too much. Forgot the spec (20 mil?), but most mechanics say "matchbook cover thickness". To adjust the gap, you have to remove the outer plate and add or remove thin washer shims to the end of the shaft. Note that often that securing bolt is a LH thread, and you need to use an impact wrench (or hammer a manual wrench) to loosen it since the compressor shaft will just spin otherwise.
 
Pishta, as I mentioned before, suspect an "in harness" spike diode. Carefully cut back the insulation and see if there's one in there and clip it out and check it. "Might be shorted."
 
67Dart273 said:
Pishta, as I mentioned before, suspect an "in harness" spike diode. Carefully cut back the insulation and see if there's one in there and clip it out and check it. "Might be shorted."
Click to expand...
Got it handled...took the old one out and the 2 wire harness was charred behind a metal bracket and was shorting to ground. Yard pull had good harness, bolted it in with old spacer, blamo! Cold air....Nice $18 bucks spent. still working.....
 
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