1999 Kia Sportage

Hello and thanks for donating

One of the leading causes of a car stalling or loosing power with the A/C on is a seized compressor. If there's screeching, smoking, stalling and the air blows warm out of the vents whenever the AC is turned on it's a good guess that the compressor has locked up. If there is just a belt squealing but the car doesn't stall and the AC cools, more than likely the belt or the tensioner is worn. The most likely cause of a car not idling high enough and sometimes stalling with the A/C turned on without any of the other issues mentioned can be an IAC (Idle Air Control) motor.