A/C clutch not engaging

Last 8 digits of VIN are 1F208882.

Is there supposed to be positive 12 volts at Pin 17 during a No AC request condition?

Does the computer climate control module ground the AC request Pin 17 on the PCM during an AC request on condition?

Hi 2CarPros, you asked me the question below.

"You stated way back you had power there. The wire changes color to dark green/white as you see. Is there power at 17 with the connector disconnected? Look for power on the harness, not the ECM."

I don't have positive 13 volts on red pin 17. It doesn't matter if the A/C light is on in the HVAC control module or if I turn it off. red pin 17 is always a ground.

Also I have purchased a PCM.

Pin 17 will have power as it comes from the relay control side.

The ECM grounds that the wire and the relay will engage and send power to the compressor.

From all indications and results, you need an ECM. I would not use a used one. I would get a new one.

Roy

On the schematic red pin 17 is the A/C request and comes from the HVAC Control Module; and not from the from the relay. I never said I had power at red pin 17. We only verified that there is power at the pressure switches. My vehicle only has 2 pressure switches. It doesn't have the high pressure switch between the (PCM red pin 17) and the (HVAC Control Module). That is unless I misunderstood.

Thanks for your help.

Pin 43 is the relay control. That is the wire you need to be testing, not 17. 17 is for the high-pressure switch.

Roy

On my truck pin 17 is just an A/C request. We have determined that there isn’t a pressure switch connected to pin 17. The HVAC Control Module sends a 12 volt signal to pin 17 to turn the A/C on. So what does it mean if I don’t have 12 volts at pin 17?

Correction
Pin 18 should have Pin 17.
I corrected the typo.

A wiring issue to that pin.

Roy

It wasn’t the PCM.
There is a third pressure switch. It’s a high pressure switch mounted on the back of the A/C Compressor. The A/C request signal goes through it then to Red Pin 17. I must of knocked it lose when I unbolted the compressor to replace the A/C Clutch. Anyway the A/C is fixed now.

Good job!