Thermostatic Air Cleaner: Testing and Inspection

1. Check system to make sure that all hoses and ducts are connected. Check for kinked, plugged or deteriorated hoses.
2. If engine temperature is above 77° F. on Buick, Cadillac, OLDS & Pontiac or 80° F. on Chevrolet, remove air cleaner and allow to cool. Place a cold wet cloth over sensor to aid cooling.
3. Install cooled air cleaner with cold air intake disconnected.
4. Start engine and observe damper door. Door should be closed when engine is first started and gradually open as engine warms up.

NOTE: Some air cleaner sensors have a check valve that delays the opening of the damper door. Length of time depends on temperature, which may vary from a few minutes at 0° F. to a few seconds at 70° F.

5. Disconnect vacuum hose from vacuum motor and apply a minimum of 7 inches Hg vacuum to motor. Damper door should completely block off snorkel assage. If not, check linkage for bining condition or diaphragm for leakage.

NOTE: To check vacuum diaphragm for leakage, pinch vacuum hose to diaphragm while applying vacuum as noted in Step 5. Damper door should remain closed. If not, replace vacuum motor.

6. Reinstall air cleaner. As the engine warms up, damper door should start to allow outside air and heated air to enter carburetor.
7. If air cleaner operation is not as specified previously, or operation is doubtful, check temperature sensor as follows:
a. Start test with air cleaner temperature below 77° F. on Buick, Cadillac, OLDS & Pontiac or 80° F. on Chevrolet. If engine was running recently, remove air cleaner and place thermometer as close as possible to sensor. Allow air cleaner to cool below calibration point of sensor.
b. Start engine and allow to idle. Damper door should move to close the snorkel passage immediately, if engine is cool enough. When damper door starts to open the snorkel passage, remove air cleaner cover and read thermometer. Thermometer should read 100 +/- 20° F for Chevrolet or 123 +/- 20° F for Buick, Cadillac. OLDS & Pontiac If not, sensor is malfunctioning and should be replaced.