A/C clutch not engaging

Hi,

Let's start with A/C pressure. If the system is low, it will prevent the compressor from coming on to protect it. Get a gauge set and let me know what the pressures are with the engine off. If that is not it, then we can move onto the relay to see if that is an issue.

Okay. Is this on the high or low side or both? Also, is that when the engine/AC is on or off?

Okay.

Then you have a compressor issue. You should have about 30-40 PSI on the low side when the A/C is on and about 2.5 times ambient temperature on the high side. When they are equal, it means the compressor is not operating properly. Take a look at the attachments.

The fact that it does not work except when you apply power shows this is the issue. I would check the black and grey wire going to the compressor for an issue. If the wire is okay, then your A/C control module is most likely the issue as long as the fuses to the module are okay ( I assume they are because they are not exclusive to the compressor). Fuse F48 and F34 need to be checked.

Let me know what you find and we can go from there.