Im stumped here. I know A/C pretty well so Ill state what Ive done so far.

Comoressor and 3 wire binary pressure switch has been replaced. System has been charged and currently at 100 equilized with system off. Enought to cause a short cycle or compressor engagement. When I jump comp directly. I have 45 on low side 270 on high side. Give or take 95 degrees today.

I have nothin. I have power but no ground to compressor clutch. Comp is brand new.

I have pcm trigger and 5v into 3 wire pressure switch and 1.1 volts out.

All fuses are good and the A/C relay and I can junp the compressor and make it engage.

When pulling the relay. I have power on all 4 legs when Relay is in and power on 30, 86 and 87. I didnt think I should have power on the load side with the relay out.
i do not have a ground wich I believe comes from PCM. (ADD THAT PCM is new also) I can jump ground with relay installed and still not get activation.

When I unplug the compressor I have power no ground but when plugged in I have power at both leads on the plug of compressor.

I am baffled here and not sure what to do or check next.

Also the evap switch is jumped as well to elimiate that as the culprit.

Any help would be begged for right now.

 

Pin 30 should be hot at all times.

Pin 86 will have power with the ignition on.

Pin 85 is the PCM side of the control circuit for the relay. PCM triggers the relay be grounding pin 85. With the relay plugged in, and ignition on, you will have power there.

Pin 87 Is power feed to the compressor clutch. It should only have power when the PCM triggers the relay.

Compressor grounds to the valve cover. (right side, supposedly.... not real clear where exactly.)

Low pressure switch gets a signal from the PCM. I would suspect 5 volts..... other side of switch just goes to ground.

High side is a transducer. Three wires, 5volt feed, signal back to pcm, and a ground.

 

So Im looking for a problem in the relay circuit? Do you know the pin location for the pcm to see if I have a break in the wire from it to the relay?

Im so thank ful for your help. This one has me baffled for sure.

 

I used the wiring diagrams found here for reference.

Should be a blue (light or dark....) wire with orange trace. Goes to connector 3 pin 1, or 11, depending on if you have NGC, or JTEC communication protocols. (a transition year??? No idea.)

 

That is ground coming out of PCM correct? And rhat goes straight to relay to activate the compressor? Cause I have power to compressor. Im missing the ground. I can jump ground at relay but nothing happens. I can jump ground at compressor plug and it works.

I want this thing out of my garage

 

Okay. This is where Im at currently. I pulled all the plugs and tested continuity. I have all the wiring from tansducer pressure switch to pcm. I have contunuity from compressor ground to relay. If I jump pin 87 with relay installed compressor engages. So thats what Im missing.

What turns 87 into a ground? That come from the PCM? The diagrams Im seeing dont show what provides this or what wire. I also have the evap freeze switch jumped.

Im so frustrated here

 

If you have power at the compressor, everything is working as it should be..... If you ground the compressor, black wire in the connector... does the compressor then run?

 

Yes if I ground pin 87 from relay when installed the compressor engages. The compressor has power all the time. It needs the ground to activate. Compressor has power no matter what and wondering if thos is normal as it doesnt seem so.

That pin 87 wire goes directly to compressor plug. I checked this when I was running continuity tests.

So basically I need pin 87 to be ground. Im pretty sure the PCM does this but man Im lost here. I cannot for the life if me figure this pile of **** out.

Also the evap freeze switch is showing open. Is this normal or should it be normally closed? Either way Ive jumped it and left it open. Makes no difference.

Im at a loss. Ive never had a vehicle defeat me this bad. I guess cause I dont know what Im missing and where

 

Erm, that ain't right. Pin 87 should be the power FEED to the compressor. Where does the black wire from the compressor connector run off to?

 

Thats what I thought too. I dont know. The power to the compressor is qll of the time. Even with the fuse and relay removed. Thought that was strange.

The blue with black wire on compressor is thebwire from pin 87 from relay. The relay wont engage unless I jump ground to pin 85. Then it will power 87. So If I could get ground to the 85 pin. I could rewire compressor and make work.

So checking things. The one wire blue and black goes to pin 87 of relay and the constant power I have to compressor is all black and it goes into the harneess twords the engine and I lose it.

This has me so confused Im just at a loss here. Nothing makes sense on this system.