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Q: A/C compressor wont engage, weird electrical issue??

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Hello, My A/C compressor coil will not engage. The compressor itself works if I unplug the coil and run jumper wires straight to the battery then the coil engages and I get nice cold air. The coil resistance is 4.0 ohms and draws 2.3 amps when jumped to the battery which appears to be in spec from other internet sources. So I believe the compressor and coil are good. Here is where it gets tricky. The wiring harness plug that goes to the coil has 13.4 volts only if its unplugged from the compressor coil plug? Soon as I plug it into the coil the voltage drops to zero? On wiring diagrams it shows the compressor coil is on the ground side of all the electrical components of the entire a/c system so I'm getting power up to that plug until I plug it in to the compressor. I did a test of running jumper wires from the wiring harness plug over to a chevy blazer's a/c compressor coil (which for sure works) to see if the jeep electrical system will power the coil and the voltage shuts off thesame

My car has 173000 miles.
My car has an automatic transmission.

A: Go to fuse 21 in the engine compartment to ...

Go to fuse 21 in the engine compartment to see if power goes away when you test it while the compressor is connected. If the power stays above 12.5 volts, check connections to the A/C clutch relay in the power distribution center next to the battery. If the connections are good then replace the relay and retest the components. The connection should not be loose and may show signs of heat or arching on the relay and connector. If you need some help with this issue, consider YourMechanic, as a certified technician can diagnose the cause of this electrical issue and fix it accordingly.

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