Control of Fast Idle For Cold Engine Operation

Air Cut Valve:

PURPOSE
Provides fast idle when the engine is cold.

OPERATION
When the engine is cold, the air cut valve opens an air passage which allows intake air to by-pass the throttle valve, providing cold/fast idle.

As coolant temperature rises, the valve closes off the air passage, reducing idle speed.

CONSTRUCTION
The valve is a rotating shutter valve. A bi-metal spring reacts to surrounding coolant temperature to either open or close the valve.