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Q: RPM revs too high

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My car has a problem with the rpm. When in idle it revs to about 2000 rpm and that's when the compressor kicks out. When the compressor kicks in it goes down back to 1200 rpm which is really high.

My car has 188000 miles.
My car has an automatic transmission.

A: Hi, thanks for writing in. This is a sign o...

Hi, thanks for writing in. This is a sign of a failing idle air control valve. This is a unit that is located on or near your intake manifold that monitors the air intake as it is mixed with fuel prior to being injected into the engine. This valve is controlled by the vehicle's computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. However, when the engine RPM drops below the normal range of 800 RPM (for most cars), it is more than likely that you are dealing with an IAC valve problem. In cases where this valve is clogged or is nearing its replacement age, your vehicle will stall instead of idling after the release of the throttle. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this rough idling issue for you, and make or suggest any repairs as needed.

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