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Q: ac compressor clutch not engaging

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Compressor quit suddenly while driving , cooled great prior to that.( I did here a noise a few minutes prior to noticing it wasn't cooling but thought it was ridges in the road) A shop told me the compressor was bad but due to the high price I got a second opinion. The second mechanic told me that the clutch was not engaging and that it could be just a bad coil and that he couldn't verify a bad compressor without the clutch engaging. He said the system has pressure and that the coil is getting power. What are the odds that the coil is the only problem and I could expect to get a few more years out of the compressor?

My car has 111000 miles.
My car has an automatic transmission.

Let’s assume the clutch is not engaging. The clutch coil should simply be tested to determine if coil failure is the cause and it’s easy to do. The integrity of the clutch coil can be tested on the car using an ohmmeter. Of course, the Factory Service Manual (FSM) specification for your clutch coil is the one to compare against, but typically an A/C compressor clutch coil will have a measured resistance (cold) in the range of 2 to 5 ohms. If the resistance of the coil reads outside that range (or, more accurately is not within the FSM specification) then there’s something wrong with the coil. The diode in the circuit (if equipped) should be tested as well. If the coil is bad, it can be replaced and during replacement the compressor is evaluated for freewheeling (i.e., normal) operation. If it is not seized, you can likely re-use it. While any compressor is out of a vehicle, it’s always a good idea to re-seal it. The parts are very cheap but there is labor involved. Mobile replacement of the clutch assembly (including the coil) will save you money on the repair. If you desire that a certified professional from YourMechanic test the coil and evaluate the compressor’s suitability for repair (i.e., refurbishment with a new clutch/coil assembly) please simply request an A/C system diagnostic. Please let us know if you have follow up questions or additional concerns.

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