Why does car stall when AC is on?

Why does my car hesitate when AC is on?

A vehicle that is stopped stalls when the steering wheel is turned to full lock only when the air conditioning is on.

The power steering pressure switch signals the computer to increase the engine idle speed during parking-type maneuvers. If the vehicle has a bad power steering pressure switch, the engine could stall at idle when the steering is moved to the full lock position. This is due to increased load on the engine from the power steering pump.