I connected the battery to the compressor and the clutch does engage. The A/C lines have a static pressure of 100 PSI on both high & low, so that's good. The Clutch relay is good and is getting 12v on pin 30. Also the plug going to the compressor is getting 12v. It seems the PCM is not sending ground to the compressor. I tried a new Pressure Transducer and the clutch is still not engaging. With the car running, I get 12v from the car to the compressor, but ground is not zero and it reads 6 volts. I can't figure out why is not grounding. I don't see any breaks in the wire and most of the wire is wrapped. I don't know what to do next.

So far, I have eliminated the compressor as the problem... since the clutch engages connected directly to the battery. The gauges read about 100 PSI on both sides and that eliminates not having enough pressure in the system. Today I replaced the Pressure Transducer or switch and the clutch still does not engage. I can't see any wires ripped or cut from what I am able to see. Clutch relay is getting 12v on 30, but I don't seem to get ground on the control pin 85 and 86. If I bypass the relay with a paper clip on pins 30 and 87, the clutch does not engage. I may have missed something and just need to be lead in the right direction.

 

When I test the compressor directly to the battery I did connect the positive and negative and the clutch did engage. Where I am not getting ground is when I test the plug coming to the compressor. The plug that comes from the car to the compressor does have 12v, but no ground. Same goes for the clutch relay, if I am testing it right. I watched this video and did what he did. But he found a wire ripped and thats not my case from what I can see. He tested the relay connection on the control 86 and 85 and then the load 30 and 87. I do have 12v on 30. When he test 85 and 86 the control, he gets 12 volts, but when I do it, the number are all over the place.

 

There are a few things in your 2 posts that appear to be jumbled up, but I'll just focus on one thing to start with. The PCM supplies ground to the clutch relay, not the compressor itself (the compressor has a fixed body ground). You said that the clutch engaged when you hard-wired it directly to the battery + and -. But you also said 'there was power at the plug', and also that jumping clutch relay pins #30 to #87 did not cause the clutch to engage. All of that sounds like the compressor ground to the body is bad, but perhaps I'm not understanding everything that you wrote.

In any case, you can test that ground simply by attaching one of the multi-meter leads to the battery + terminal, and probe the other lead to #2 pin of the compressor connector (black/grey wire). If that body ground is good, the meter will display battery voltage. If that test proves the compressor ground is bad, that would confirm most of what you wrote. But if the compressor ground is good, then a few things don't make sense, and will need to be resolved.

 

I did 2 things. First I tested the compressor by connecting the battery + & - to the compressor and the clutch engaged. With that test I came to the conclusion the compressor was not the issue. So I then tested the plug coming to the compressor from the car and I did get 12v, but no ground and That was with the car off. So then I went to the clutch relay and I was getting 12v on 30 and 30 to 87. Then I put one probe on 85 and the other on 86 and did not get ground just random numbers. I checked the pressure switch and I am getting 4.98v on the red and yellow, I am reading pressure on the sensor wire, but no ground wire.

I hope I was clear this time. How do I test the ground on the compressor, since I assumed that the ground was good when the clutch engaged directly to the battery.

Please help me fix this issue. I really don't want to spend more money getting it diagnosed at the dealership. Thank you.

 

Read the second paragraph of my previous post.

 

Been working on it for a week and I think is the PCM. I gave up testing anymore and will take it to the dealership for diagnosing. I will post back with result.

 

I'm not a part-hanger myself, but if that's your choice then why not just buy a PCM online, programmed to your VIN. You can buy one for less than it will cost you for a just a diagnosis at Dodge. The online seller offers a money back guarantee, and it takes half an hour or less to swap it out.

 

The way I am seeing it... I am not sure is the PCM. I know on eBay for $115 I can send it in, get it repair and have it shipped back. I need to know for sure where the issue is, so I am not spending money on things that don't need fixing. I really want to fix it myself, but I tested everything that I know how to test. I don't know how to check the PCM or test it to see if its not feeding ground to the clutch relay. I didn't test the compressors ground, because the clutch engaged when I connected it to the battery. If the internal compressor ground was bad, the clutch would not engage. Do you think I still need to check for ground on the compressor?

 

According to what you wrote, you directly connected the compressor to the negative battery terminal, instead of the ground wire at connector pin #2. So that test bypassed the ground wire.

In addition, you also jumped clutch relay pins #30 and 87, which supplies power to the compressor and should immediately engage the clutch if the key is at the 'ON' position. But you wrote that it did not engage. The only reasons it would not engage is if the compressor is bad, or the ground wire is faulty. But you also reported that the clutch engaged when connected directly to the battery, so the compressor already tested ok.

The results of the prior testing that you did points to a bad ground wire, so yes, you should definitely test the ground wire as I described in the earlier post.

 

I did what you said. I set my multi meter to 12v connected the red probe to the battery + and used the other probe to test the black and white wire. I did not get 12 volts and the multimeter readings were all over the place. To make sure it the multimeter was working properly, touched the engine and I got battery reading 12v.

Does that mean the compressor has a bad ground and the reason it worked before, was because it was using the ground from the battery.

According to the diagram the PCM only sends ground to the clutch relay and the compressor supplies its own ground. But reading online, if the compressor is a 2 wire then it gets its ground from the car. If the compressor is a single wire, then it has its own ground. This compressor is a 2 wire connection. Meaning it does not have its own ground. Is that correct?