Q: I have a 2011 hyundai genesis coupe 2.0 84540miles. When the ac is turned on the car shakes drastically.

The a/c system loads the engine when the a/c is turned on. To maintain engine speed and power, there is an "idle-up" control circuit. That control may be malfunctioning in your case. Another possibility is a problem elsewhere in engine management or controls, such as in the fuel or ignition system, such that the engine cannot compensate for the added load from the a/c system. A faulty idle-up system is the first possibility to rule in or out though. Initially, you need the problem diagnosed and pinpointed, so the recommended service is an engine idle diagnostic. If you request that service, the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.