The AC belt connects the engine’s crankshaft to the air conditioning compressor clutch. When the AC is turned on, this belt bears the load of the compressor, allowing refrigerant to circulate and cool the cabin. Since the AC compressor creates significant resistance, this belt is subject to high stress. A worn AC belt may chirp or squeal when the air conditioning is activated. While a broken AC belt usually won’t stop the car from running, it will result in a total loss of air conditioning function.