90 chevy dying

I have a 90 chevy truck. It has the V6 in it. When I turn the A/C or defroster on the truck wants to die when it is lukewarm. When the motor is cold it will run fine and when the motor is completly to temp it will run fine just in the interm when it has not reached full operating temperature. The compressor turns fine and does not appear to be dragging. I know I am low on freon as the compressor turns on and off frequently. Could that be part of the problem. Is it putting too much load on the motor. I was wondering if the IAC could be the problem (Need cleaned????) or possibly something in the throttle body. Any help would be greatly appreciated. Thanks.

I would start with the iac, if it is moving slow that may be your problem. Any time the a/c is on it is putting a load on the motor, but kicking on and off like that is hard on the clutch.

Is there a way to clean the IAC or do I need to replace?