Well I am bridging the pigtail going to the sensor on the accumulator. But I also tested for continuity on the sensor itself, and there was none.

Yeah, light for the a/c button came on when I pressed it, truck was running and had reached operating temp.

 

It might, or that the switch is bad. It should be closed and pass power if the system is good. Replace the low pressure switch if you do verify you have enough system pressure. It's got a check ball so it can be replaced without losing charge. Do you ever have power at the low pressure switch? Sounds like there are multiple things going on here, lol. Jumpering the low pressure switch will force it run with low pressure....... so that's not the issue.

The head unit could be bad or could have a stored code holding it out too. You need a scan tool to verify that however.

And the light on the A/C stayed on I assume with the pressure switch jumpered but still no compressor. If there is no power to the a/c clutch it could be the PCM, head unit or a bad relay, although you say you tried that. What about new relay and jumper the low pressure switch. See what that nets..

Again a scan tool could force the clutch on and prove the compressor is working correctly......

 

I am getting with Wheatley next week, so hopefully that will get me somewhere. And I swapped relays with the fuel pump relay and no change. The a/c light did stay on.

 

So new discovery. I decided to double check the compressor relay today in the underhood fuse box. I was prying it up with my 90 degree metal pick and it bridged the connection and made a clicking noise at the compressor. I thought, "weird." fired the truck up and turned the a/c on, and when I bridged it again, the compressor kicked on. I only kept it on for a few seconds just in case freon was low. Swapped the relay with a working one, so not a bad relay.

So does that mean the signal is not coming through to turn the compressor on? How do I test where the problem is now?

 

At this point you can start thowing parts at it or get a tech2 hooked to it. I have my guesses but I'd sure hate to see you waste money if something else is causing it. You might have something as simple as a bad temp sensor causing all this.

 

Ok, so a Tech2 will actually identify what the problem is? To be honest, I didn't know the hvac system threw codes.

 

Get a wire and jump out terminals 30 and 87 after you take the relay out.
with the key on, if you jump those terminals, it should click the compressor clutch..
Might have a loose connection at the relay?

 

I'll give that a shot

 

could have a broken wire also..

you can check the ohms from pin 87 i believe to the compressor clutch connector..

 

30 to 87 turns the compressor on.