A/C in my car started blowing warm air. The a/c compressor clutch was engaged and both radiator fans were running while the engine is running. Shut off engine and did a quick pressure test by pushing on the low pressure schrader valve and there was NO R-134a. Tried to pull a vacuum and the system will not hold vacuum.

Thought low R-134a would stop the compressor from running via pressure switch, so tried turning on/off the a/c with the engine running and the compressor and fans remained on. Wiring diagram shows fans + compressor are controlled by the PCM. The PCM gets data from the HVAC unit, relay control module, and gauge control module.

Here is where I am confused starting on page 22-99 in my 04-07 shop manual I got from automanualsource.

The B-CAN self diagnostic without a HDS in my shop manual should repeat codes by flashing the dome light by shorting the MPCS Service connector on the under-dash fuse box. A code 11 (long flash + short flash) flashed only one time and the cluster shows "no" meaning no B-CAN DTCs stored. Code 11 is listed as relay control module in a table at the end of the diagnostic. The manual is not clear if the dome light or the cluster would flash this code. Checked the relay control module connector in the engine bay fuse box and the pins/connector look good. Still need to test the wiring.

I need to figure out what component is signaling to the PCM to turn on the a/c regardless of zero R-134a pressure or having the a/c turned off on the HVAC controls. Code 11 is pointing towards the relay control module which is integrated into the engine bay fuse box.

If you have suggestions, let me know. I'll keep working on it. Not having a HDS makes this type of work extremely difficult. Thanks.

As for the a/c system...
I know the compressor is shot, because the low pressure hose had metal shavings in it. Also, the thermal protector was melted and the pressure relief disc was ruptured. The high pressure line didn't have any metal in it. Will replace compressor, condenser, expansion valve, evaporator, and all o-rings. Flushed the lines with water, then dried them with denatured ethanol. Will flush the lines a few more times onto a white paper towel to verify I got all the metal out of there.