Idle Air Control (IAC) Valve
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IAC valve is an electromechanical device controlled by the PCM. The IAC valve is mounted on the throttle body and allows air to by-pass the throttle plate. The amount of air allowed to by-pass the throttle plate is determined by the PCM and is controlled by a duty signal.
During cold engine operation, the IAC valve opens, raising idle speed to a predetermined RPM. The IAC valve also compensates for all engine loads during warm engine operation to maintain a preset idle RPM.