Air Conditioner decreases engine power

I do not understand about the decrease for air conditioner, but if it is low on Freon or some other thing wrong like with the hvac controls that can be a cause. The hesitation may be from the load the air conditioner puts on the engine depending on temperature outside the higher the temperature the higher the load on engine. Try cleaning throttle plate on both sides and iac hole with choke cleaner that may help or cure your hesitation.