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Q: Rough idle when A/C on

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Lately I've noticed my 2004 infiniti fx45 idles rough when the a/c is running and I'm idling at a light; to the point where it feels it may shut off. When a/c is off car runs strong or when I'm driving with a/c on it runs great. It only has issues when I'm in idle. Any idea of what the issue could be?

My car has 214000 miles.
My car has an automatic transmission.

Your engine throttle body and idle air control may be clogged with carbon and engine is idling too low with A/C on causing the rough idle. Have the idle control valve and throttle cleaned out. You may also have the injection system cleaned and the combustion system cleaned to reduce carbon buildup on the back of the valves. If you want to have this looked at, a certified professional from YourMechanic can come to your car’s location to diagnose your rough idling issue and let you know what needs repair.

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