The AC in my 2001 GTP isn't working. I checked the fuse and I checked the relay and all are good. When I turn on the AC I should hear a click and hear the compressor come on but there is no click or slight blink in the lights and no drag on the motor.

Anything else to check?

Can you tell if the clutch is engaging?

Doesn't look like it is engaging.

Check the plug, make sure it'* clean and plugged in.

The plug into the compressor? I just looked it looks like it is in but I will pull it out and re-attach it.

Check it for corrosion.

Two other possibilities, a blown fuse, not sure where that is on your car. Or low refrigerant. There should be a low refrigerant cut out that will prevent the clutch from engaging.

Pulled the plug out. It looked ok and plugged it back in and the clutch now spins!!! But, still blowing hot air so perhaps refrigerant is the next step? Fuse is definitely not blown.

Connected a pressure gauge to it and it was below 25 lb. Added 18 oz and it it starting to blow a little cooler. Will get another can tomorrow to see if I can get it up over 30 lb.

Be careful with how much you put in. Total system only holds approx 2lbs. When you plugged back in and it worked, that meant there was a decent amount in the system. 18oz is a little over half the system. W/o pressure gauges on both sides and the FSM that gives you a chart of high/low you won't know the correct level of freon based on the temp and humidity.

I thought mine wasn't working well enough, but then read the FSM and it'* very thorough and interesting. Technically it'* only supposed to be about 20F cooler from the vents than external temps and humidity plays a large factor in that too.