Auxiliary Air Valve (Idle Speed): Testing and Inspection

NOTE: The fast idle thermo valve is factory adjusted; it should not be disassembled.

1. Start the engine.
2. Remove the cover of the fast idle valve.

Fast Idle Thermo Valve Testing:

Fast Idle Thermo Valve Exploded View:

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 not, replace the fast idle thermo valve and retest.

4. Warm up the engine (the radiator fan comes on).
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 coolant system. If OK, replace the fast idle thermo valve and recheck.