Engine lopes and rpm drops down to 3-400, warning lights sometimes flash. If I turn off A/C the engine will go to approx. 700 rpm and run fine.
As soon as I turn on A/C, it does it again. Runs great on highway.
I see a couple of different possibilities why the AC Lowers Engine RPM.
- Could be an engine misfire. This means the engine isn’t running quite right on all cylinders. And when the added stress of running the Air Conditioning comes into play it causes the engines rpms to drop. This would also explain the check engine light flashing. Have the check engine light trouble codes pulled and post the codes below for further information.
- The Air Conditioning system have been overcharged and the engine is having trouble turning the compressor.