Q: Car idle sputters and engine dies when AC clutch engages

asked by on June 25, 2017

When a/c is turned on, and car is at idle or in motion, the engine sputters and dies when the a/c clutch engages and rpms are increased. The a/c compressor clutch intermittently engages and disengages, I don't know if this is normal for make and model for my vehicle. Also, the clutch makes a loud "clunk" noise when it disengages and when it re-engages. I don't know if the clutch should spin continuously with the belt or not.

My car has 113000 miles.
My car has an automatic transmission.

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Hi there. In most cases, when the AC compressor and clutch engage, it will draw extra ’power’ from the engine and cause the idle to slightly drop. However, this can cause existing issues to be amplified. For example, if you have dirty fuel injectors, mass air flow sensor or EGR valve on the vehicle, the activation of the compressor clutch will make the symptoms worse and more noticeable. However, if the compressor bearings or clutch is dragging, it can "bog" down the motor even more. It’s a good idea to have a professional mechanic come to your location to complete a car idle is rough inspection to determine if it’s a normal fuel system issue or if the AC system is the source of this problem.

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