OK, I had some time to tinker today. A/C hadn't come on at all yesterday or today, which for me actually a good thing because it gives me time to test. First thing is that I believe I eliminated the wire harness. I pushed, pulled tweaked, and twisted that thing every conceivable way and the compressor never kicked on. Then I started plying with relays and noticed something. With the truck running and A/C switched to on, I would remove and re-insert the relay. The clutch would kick on for a fraction of second every time. I tested the posts that the relay plugs in to and got 14.1 on 2 of the terminals which I'm sure is correct. I then tested the voltage at the compressor harness again. Now the last time I tested it, got zero voltage at the compressor when the A/C was switch on. Today I got all kinds of readings. My voltmeter would change constantly anywhere between 0 and 14.1 and everywhere in between. Not increasing, or decreasing, but jumping. 5.1 then 1.1 then 13.9, then 3.4, and so on. At first I thought it was my tester, but I get a solid 14.1 at the battery. Than after letting the truck sit for a while I tried again. This time the A/C turned on. I tested at the harness again and got the same result. I'm no mechanic but it seemed to me that if I have steady voltage at the relay terminal, and conflicting voltage at the harness, I figured it had to be the relay, so I exchanged with one of the others. Same jumping voltage, tried a third relay, same result, and a fourth, same result.
What the hell. How is this possible. If the relay is receiving steady voltage but I'm getting jumping voltage at the harness, and I get the same result with multiple relays. What could be going on?

 

A/C work can be tricky take it to a shop.

 

There's probably an intermittent short to ground on the hot wire from the IPM to the clutch. Unplug it from the clutch and see if the voltage on the harness connector continues to jump around.
If it does, shut it down and check resistance to ground. The problem could be under the IPM.

 

We said that he cant find it is the problem

I don't know why?

Could be a bad clutch

 

I understand, but the process is flawed.

You've probably heard the saying about continuing to do the same thing and expecting different results.

Unplugging the clutch takes it out of the equation.

Now there are 2 possibilities: the PDC/IPM (whichever it is) and the wiring.

If the voltage is still fluctuating, it's probably a bad wire, either shorted to ground (the engine) or corroded.


And yet, the relay socket could also have bad/loose connections, going by the test he did by swapping relays.

 

I understand, but the process is flawed.

Yes I know that but its up to him