Thermostatic Air Cleaner: Testing and Inspection

THERMAC Operation:

AIR CLEANER INSPECTION

1. Check that all hoses and heat stove tube are connected. Check for kinked, plugged or deteriorated hoses.
2. Check for presence and condition of air cleaner-to-carburetor gasket.
3. With air cleaner assembly installed, hot air control valve door should be open to outside air.
4. Start engine and observe valve door in air cleaner snorkel. Door should move to close off outside air when engine is first started. As air cleaner warms up, door should slowly open to outside air.
5. If operation is not as described, test vacuum motor. If there is a driveability problem during warm-up, test temperature sensor.

VACUUM MOTOR TESTING

1. With engine "OFF," disconnect vacuum motor hose.
2. With a hand pump, apply 23 kPa (7 in.Hg) vacuum to motor. Valve door should completely block off outside air when vacuum is applied. If not, check that linkage is correctly installed and not binding.
3. Check that vacuum motor diaphragm holds vacuum and does not leak down.
4. Correct any linkage problems and if diaphragm leaks, replace vacuum motor.

TEMPERATURE SENSOR TESTING

1. Start test with air cleaner temperature below 30°C (86°F). If engine is hot, remove air cleaner cover and place a thermometer as close as possible to sensor. Replace air cleaner cover when temperature has fallen below the specified level.
2. Start and idle engine. Damper door should move to close off outside air immediately if temperature is cool enough. When damper door starts to open, remove air cleaner cover and take a temperature reading. It should be about 55°C (131°F).
3. If damper door did not open to outside air at the specified temperature, replace temperature sensor.