2001.
New compressor will not engage.
When I remove the clutch relay and put a safety pin in to bridge the connection everything works fine.
Cold air, refrigerant level is perfect, nothing failing at all.
Bought two new relays, neither seem to work but that'd be a hell of a coincidence to have 3 bad relays.
The pressure switch/sensor is fine.
What do I check next?

 

Oh and a code reader shows nothing faulty

 

Sounds like the signal wire to the relay is missing.
- By bridging the connector, you are completing the circuit to engage the A/C clutch. Now, you need to figure out what signal wire causes the clutch relay to bridge the connection.

Do you have a wiring diagram for the car you are working on? Start tracing the wires backwards from the A/C clutch relay.

 

I had problems with the low side pressure switch on my 01. it it has 4 wires. my 98 only has two. Had problems trying to find a new switch for my 01. When I got it to finally work, I super glued the wires in the switch.

 

The "control" wire for the A/C clutch relay comes from the the PCM connector 3 pin 1. It should "ground" and activate the relay when other conditions are met. The other conditions are the a/c controls are set to on and the PCM detects this at connector C3 Pin 23 and also detects it at the PCM at C3 Pin 22 via the high pressure switch and then the low pressure switch. The high pressure switch is a 4 wire, and also feeds the PCM at C3 Pin 13 in order to turn on the radiator fan when the A/C is engaged.

I would start by checking Continuity from the A/C compressor clutch relay "control" wire to the PCM connector C3 pin 1. the a/c clutch relay is the relay out the outer most edge "towards passenger side" and towards the front of the jeep. The control wire is the connection that is also the outermost closest to the front.

 

The a/c clutch relay uses 4 connections, the "control" I mention in the previous post. the other 3 are: battery power from fuse 9 (20 Amp) in the power distribution center under the hood, this powers the a/c clutch. Fuse 10 (15 Amp) in the junction block at the passenger kick panel, this provides the power to "activate the relay". but like I said before, the relay won't activate until the PCM "grounds" the control side of the relay.

 

Ok so we tested with a multimeter.
The relay is getting power. But I will follow up checking with the ground.
The neighboring relay is not getting power, for the fog light. (Which does not work)
The low pressure switch is not getting power.
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