The idle air control valve (IAC) controls the amount of air bypassing the throttle valve. The IAC valve is part of the output actuator, and is mounted to the throttle body. It is controlled by the power-train control module -- the vehicle's main computer, which sends electrical pulses to it, moving the valve within the actuator in or out to allow more or less intake air into the system. Replacing the IAC valve in a 1997 F-150 is simple and straightforward.
Raise the hood, and locate the IAC valve attached to the throttle body in the top, center of the engine.
Unplug the electrical connector by pulling it out of the IAC valve.
Remove the two retaining bolts with a socket wrench, then withdraw the IAC valve from the throttle body. Clean the sealing surface and throttle body assembly with a shop rag.
Install the O-ring onto the new IAC valve, and lubricate it with a small amount of clean engine oil.
Install the IAC valve into the throttle assembly; then install, and tighten the mounting bolts. Plug the electrical connectors into the IAC valve fitting.
Close the hood. Start the engine to test the operation of the new IAC valve.
