If your car is shaking when you turn on the AC, it could be a sign of a problem with your compressor. The compressor is responsible for pumping refrigerant through your AC system. If it's not working properly, it can cause your car to shake.
There are a few other potential causes of this problem as well. Your car may be low on refrigerant, which would cause the compressor to work harder and potentially cause shaking. A loose belt or pulley could also be causing the shaking, as they can put extra strain on the compressor.
If your car is shaking when you turn on the AC, take it to a mechanic so they can diagnose and fix the problem.