Thermostatic Air Cleaner: Testing and Inspection

The Thermostatic Air Cleaner consists primarily of three components, the Thermal Vacuum Valve (TVV), Vacuum Reservoir and the Air Control Flap.

The vacuum actuated Air Control Flap regulates the amount of warm or cold air entering the air cleaner housing. It should be covering the warm air intake when the engine is not running.

The Thermal Vacuum Valve supplies the engine vacuum needed to actuate the air control flap. Outside air temperature varies the amount of vacuum the thermal vacuum valve delivers to the air control flap.

Air Cleaner:

AIR CONTROL FLAP CHECKING
- Loosen the air cleaner upper housing and remove filter element.
- Turn air cleaner upper housing to expose air control flap in air cleaner lower housing.
- Disconnect the vacuum reservoir hose from the thermal vacuum valve leaving hose connected to reservoir.
- Connect a hand operated vacuum pump to the vacuum hose and operate pump.

^ The air control flap MUST CLOSE the cold air connection -1-.
^ Check vacuum reservoir for proper function or leaks.

- If either the control flap or reservoir fail the test, it should be replaced with the lower air cleaner housing.

Thermostatic Air Cleaner Components:

THERMAL VACUUM VALVE CHECKING
- Reconnect the vacuum hose to the Thermal Vacuum Valve.
- START engine and let idle.
- Check position of air control flap after 20 seconds (maximum). Air Control Flap SHOULD BE:

- With ambient air temp. UNDER 68°F (20°C)

^ Cold air connection -1- CLOSED

- With ambient air temp. OVER 86°F (30°C)

^ Warm air connection -2- CLOSED

- With ambient air temp. BETWEEN 68°F (20°C) and 86°F (30°C)

^ Between cold and warm air connection

- If either the thermal vacuum valve, control flap or reservoir fail the test, they should be replaced