Ford Freestar, Monterey 2004

Idle Air Control Valve



The IAC valve assembly is not adjustable and cannot be cleaned, also some IAC valves are normally open and others are normally closed. Some IAC valves require engine vacuum to operate.

The IAC valve assembly controls the engine idle speed and provides a dashpot function. The IAC valve assembly meters intake air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or bypass air and signals the IAC valve assembly through a specified duty cycle. The IAC valve responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine RPM and increases or decreases the IAC duty cycle in order to achieve the desired RPM

The PCM uses the IAC valve assembly to control:

no touch start
cold engine fast idle for rapid warm-up
idle (corrects for engine load)
stumble or stalling on deceleration (provides a dashpot function)
over-temperature idle boost

Removal & Installation

  1. Disconnect the battery ground cable.
  3. Disconnect the IAC valve electrical connector.
  5. Remove the 2 IAC valve bolts and the IAC valve.
  7. Remove and discard the IAC valve gasket.
  9. To install, reverse the removal procedure. Tighten the IAC valve bolts to 8 ft. lbs. (11 Nm).