Thermostatic Air Cleaner: Testing and Inspection

Heated Air Intake Components:

VACUUM-OPERATED SYSTEMS CHECK

1. Apply the parking brake and block the wheels.

2. Remove the fresh air inlet tube. Inspect the heated air duct for proper installation and/or damage. Service the duct if needed.

3. Remove components as necessary to ensure that the duct door is in the open to fresh air position (engine not running).

4. START the engine. If the door is closed, proceed to Step 7. If the valve door has not closed turn OFF the engine and cool the temperature sensor.
WARNING: Do not cool the temperature sensor while the engine is running. If R12 refrigerant is drawn into the carburetor body while the engine is running, poisonous phosgene gas will be exhausted into the area. Conduct this procedure only in a well ventilated area.

START the engine. If the door has closed, proceed to Step 5. If the valve door is open during idle proceed to VACUUM MOTOR AND VALVE CHECK.

5. START the engine and run for 5 minutes and observe the door. If the door does not start to open within a 5 minute period, note the temperature.
a. If the temperature is greater than 24°C (75°F), replace the sensor.
b. If the temperature is less than 24°C (75°F), the temperature is insufficient to operate the valve door. Run the engine for an additional 5 minutes. If the valve door has not started to open, replace the sensor.

7. Turn the engine OFF and remove all test equipment. Install all system components. START engine and check for vacuum leaks.

VACUUM MOTOR AND VALVE CHECK

1. Remove the fresh air inlet tube for access to the valve door.

2. Check the valve door for sticking or binding by depressing with fingers and allowing internal vacuum motor spring to return door to normal position. Correct any sticking or binding before proceeding with test.

3. Using an external vacuum source, apply a minimum of 54 kPa (16 in-Hg) vacuum to vacuum motor and retain. The vacuum motor should remain closed for 60 seconds. If not, replace vacuum motor assembly.