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Q: Engine Reving Up on 2004 Pontiac Grand Am

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
When I turn on the A/C and the compressor engages, the engine will over rev to about 2000rpm - it is normally around 900rpm. When the a/c is turned off, the engine will go back to around 750rpm
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Engine timing usally gets advanced when the AC is turned on so in that sense the engine may run faster.
I suspect you have a stuck Idle Air Control Valve,it is what controls normal Idle speed.
You can try to remove it and spray with WD40, they build up carbon or get cooked from engine heat,,,,
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