03' Tiburon Low Idle/shaking with A/C?

[firebird1999]

Hello all, I have recently been driving around an 03' Hyundai Tiburon and I noticed an issue when sitting at idle with the air conditioner on. When the car is started/at idle with the A/C on the car starts shaking like crazy and the RPMs drop down to 500 and feels like the cars going to die. If I give the car some gas or turn off the A/C the car runs perfect at 750rpm with the A/C off. It seems to me that for some reason the car is not compensating for the increased load on the engine? I know very very little about this car and have no idea where any of the sensors are. Also, there are no check engine lights currently on only the anti-lock brake light, which is another issue entirely. Thanks for any help I receive!!