Troubleshooting a Car's AC Compressor Clutch.

The air conditioning in my Wife's car stopped working yesterday and by listening to the engine when engaging the AC button, the compressor didn't come on. Given the prior history of this vehicle I knew where to start my checks.

Step 1: The AC Compressor Clutch.

I disconnected the 12v connector for the AC clutch prior to my testing.

Step 2: The Tool.

My fluke multimeter will be used to test the clutch solenoid.

Step 3: Clutch Solenoid Coil Check.

Between chassis and the clutch lead wire the resistance needs to be approximately 3ohms as per the Hyundai trajet manual. As you can see I have an open circuit to deal with. However as I wiggled the alligator clip on the clutch wire, the reading varied!

Step 4: Further Testing and Conclusion.

The clutch wire felt broken along its length. I cut past the break and exposed the wire to do a repeat test. I made sure to check the other lead from the coil that is tied to the body of the compressor, that was in good condition mechanically. Sadly at over 400 mega ohms the clutch coil has failed.

Tomorrow we will take the car to an air conditioning service center to have the clutch coil replaced.