Idle Air Control Thermal Valve

Idle Air Control Thermal Valve




Description
To prevent erratic running when the engine is warming up, it is necessary to raise the idle speed. The idle air control thermal valve is controlled by a thermowax plunger. When the engine is cold, the engine coolant surrounding the thermowax contracts the plunger, allowing additional air to be bypassed into the intake manifold so that the engine idles faster. When the engine reaches operating temperature, the valve closes, reducing the amount of air bypassing into the intake manifold.

Inspection

NOTE: The idle air control thermal valve is factory adjusted; it should not be disassembled.

1. Remove the cover of the idle air control thermal valve.
2. Start the engine.




3. Put your finger on the valve seat area, and make sure that there is air flow with the engine cold (engine coolant temperature below 86 °F, 30 °C) and idling.




If there is no air flow, replace the idle air control thermal valve and retest.

4. Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on, then let it idle.
5. Check that the valve is completely closed. If not, air suction can be felt in the valve seat area.

If any suction is felt, the valve is leaking. Check engine coolant level and for air in the engine cooling system.

If the cooling system is OK, replace the idle air control thermal valve and recheck.

NOTE: If the cover of idle air control thermal valve was removed, do the PCM reset procedure.