The amount of air that enters a vehicle's engine is an important factor for controlling how well the car functions, including its idling speed. One component, the IAC valve, helps control this idling for peak performance.
An IAC valve—or idle air control valve—functions by allowing air to enter through the throttle body. If sensors throughout the engine perceive too much air, the IAC can close off this air passage, effectively regulating the idling speed.
If there is a problem with the vehicle's idling speed, there is a way to check the IAC valve. Detach the IAC from its housed area at the throttle body. Turn the ignition switch to "on," but do not turn start the engine. If the IAC functions by moving in and out, then the IAC is working properly. If there is no motion, it must be replaced.
The IAC can be subject to carbon deposits built up on its exterior. If checking the IAC is needed, make sure to verify its cleanliness before reattachment. If needed, clean with an aerosol carburetor cleaner for best results.
