Checking voltages at ECM. Looking for wire or wires in harness for supply to high pressure sensor under hood a right Headlight. Color and volts with switch on, full charge,.
my diagram shows b/w ground, b/y 5v power supply,, W--1.0-4.0. This is a 2006 revision, would colors have been different before revision? Stumped is the word of the day.

 

did you check the ribbon cable behind the controls?

 

I did. Looking at BCM at the moment.

 

have you tried jumping the relay on the AC coil to see if it engages when the engine is running?

 

You can jump the coil at the PDM, L/Y wire and it engages fine,

 

so when you jump the compressor relay, the A/C system does not cool the vehicle? What temp is coming out of the vents with the compressor jumped for like 4 minutes?

Is the AC button orange light blinking when trying to activate?

Any DTC's?

 

Most likely you have a low system charge so I’m not sure I’d be cycling the compressor too long. If you can access the valve, give it a little push with a small screwdriver to check the pressure in the system…at static (not working) it should be around 90-100 psi, so there should be significant pressure there (keep face away). Less pressure means you’re gonna be headed to a shop for the repair.
Otherwise you may have a sensor issue and I’m not sure what kind of sensors they use in these, but what I usually do to test is take the plug off and short it together if it’s a 2-wire sensor. If everything works then you’ve found your problem.