Q: I have a mazda 1998 protege dx when i turn on the ac the car starts to shake alot but when i turn off the ac it runs normal .....

Hi Omar. Thanks for contacting us today. 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. Since there are multiple fuel and ignition systems that could be faulty that cause this to happen, it’s best to have a professional mechanic complete an onsite inspection to determine what repairs are needed to resolve this issue.