Q: Why does my car shake when I turn the a/c on?

Hi there. Shaking with the A/C on can be caused by a number of reasons. The a/c compressor puts a lot of strain on the engine because the compressor is similar to being a small engine itself. When the a/c is switched on, the engine control unit should trigger components such as the idle speed/air control motor, to increase the idle slightly to compensate for the extra drag of the compressor. If that does not happen, then the additional drag can cause a low,shaky idle and even cause the engine to stall. Stalling can happen more often with the a/c on and turning the steering wheel as the power steering pump also creates drag on the engine. Excessive shaking can also be attributed to weak/broken motor mounts as well. It’s probably a good idea to have a professional mechanic complete a vehicle shaking inspection to determine why you are having these problems.