Long story short, my evaporator had a hole in it and I didn't have A/C for two years. Finally got the $ together and had a guy fix it who is a MOPAR dealer tech. Drove it home and it worked all the way. Left the truck sit for a couple weeks (normal - have another DD). Drove it uptown the other day. A/C worked great for a while then quit. Clutch was not cycling or engaging. Took it home an started trying to diagnose it. Jumped the low and high pressure switch. Nothing. Checked fuse. Good. Pulled A/C relay and tested for hot and ground in the PDC. Two hot, two ground. Put A/C relay back in. Clutch engaged. Revved motor. Clutch disengaged. Couldn't get it to re-engage. Got frustrated and quit messing with it. Sat for 3 days. Started it today. Clutch engages immediately. Turned it off. Loaded door in back, wife in front, and off we go to the Menards. A/C working great. Got almost there and it quit again. Never reengaged after it quit. WTH????? Too much freon, too little freon, or is there some friggin sensor or something I can change out? Can the A/C relay go bad? I don't have any gauges and it's a pain in the rear to get with the guy who did it. SO - do I try to add freon when it first works on a cold start - do I take a screwdriver and let some out - or what part can I change??? Wife is gonna kill me if I don't get this thing going and I'm tired of messing with it.....

 

Try swapping the a/c relay with another one first.

 

There is a zener diode in the clutch circuit. That may be malfunctioning. They used to put them in the pigtail wiring, but on yours I think it's on the clutch itself. Most people overlook it in the wiring diagrams.

 

Is there a way to check that?

 

Where is that thing at?

And is it common for the Relay to go bad? This seems like a deal that when something heats up it quits???

 

They solder it to the clutch on top or on the bottom backside. I could paste the long nerdy way to check it, but the easiest way is to have a test light handy when it stops working. Check your voltage in and your resistance to ground (AT THE CLUTCH CONNECTOR-Unplugged) If you have both, then you know the clutch itself is causing your problem.

Yeah, old relays can do weird things when they heat up. Switch it with a know good one from another slot. I always use the horn in a pinch.

 

I had power at the clutch connector. At least enough to make my test light light. I have a couple multimeters but am clueless on how they work.
I will try the relay tomorrow. Thanks!

 

The test light should be as bright as when you connect it across the battery terminals. I am talking about a non-powered/conventional type.

To check the ground you can connect the test light clamp to the battery positive and the pointy tip to the ground terminal. (ac clutch disconnected) Should be same intensity.

As far as how to use the meters...Google is your friend. Don't let it psych you out. It's a skill you can use other places besides automotive. If you don't come up with anything soon, i'll post a list of other checks you can do

 

I have same exact issue with my A/C, works great for ten minutes on cold start, then quits. I will try the checks TNtech mentioned. :-)

 

get your hands on a set of gauges, its not engaging because the fact that you have either too much or too little freon. My guess is too little. This is what will help you fully diagnose this issue, other thing is that there is probably still a leak somewhere else. When you use gauges though jump the plug coming off of accumulator. If your able to get a vacuum pump once you've acquired gauges leave it in a vacuum disconnect and leave all fittings closed if vacuum decreases to atmosphere you got a leak, more accurate way is to use a micron gauge though. all these tools are fairly expensive though.