Thermostatic Air Cleaner: Testing and Inspection

Thermac Operation:

INCORRECT TAC OPERATION:

1. Hesitation during engine warm up may be caused by:
a. Heat stove tube disconnected.
b. Vacuum diaphragm motor inoperative.
c. No manifold vacuum.
d. Damper door does not move.
e. Missing air cleaner housing to TBI seal.

2. Lack of power, pinging, or sluggish on a hot engine may be caused by:
a. The damper door may not be opening to outside air.
b. The temperature sensor does not bleed off vacuum.


THERMAC AIR CLEANER CHECK

1. Inspect system to be sure 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 throttle body gasket seal.
3. With air cleaner assembly installed, and engine not running, the damper door should be open to outside air.
4. Start the engine, and watch the damper door in air cleaner snorkel. When the engine is cold, the damper door should move and close off the outside air. As the air cleaner warms up, the damper door should open slowly to the outside air snorkel.
5. If the air cleaner door fails to operate as previously described, perform a vacuum motor check. If the door operates, it may not be moving at the right temperature. If the driveability problem is during warm-up, perform the proceeding temperature sensor check.



VACUUM MOTOR CHECK

1. With the engine not running, disconnect the vacuum hose at the Vacuum Diaphragm Motor.
2. Apply at least 23 kPa (7" Hg) of vacuum to the vacuum diaphragm motor. The damper door should completely block off outside air when vacuum is applied. If not, check to see if the linkage is installed correctly.
3. With vacuum still applied, trap the vacuum in the vacuum diaphragm motor by bending or pinching the hose. The damper door should remain closed. If not, replace the vacuum diaphragm motor assembly.
NOTE: Failure of the vacuum diaphragm motor assembly is more likely to be caused from binding linkage or a corroded snorkel than from a failed diaphragm. This should be inspected first, before replacing the diaphragm.
4. If the vacuum motor checks out okay, check vacuum hoses and connections. If okay, then proceed to the temperature sensor test.


TEMPERATURE SENSOR CHECK

1. Start the test with the air cleaner temperature below 30°C (86°F). If the engine has been running recently, remove the air cleaner cover and place a thermometer as close as possible to the air temperature sensor. Let the air cleaner cool until the thermometer reads below 30°C (86°F), approximately 5 to 10 minutes. Reinstall the air cleaner on the engine and proceed to step number 2.
2. Start and idle the engine. The damper door should move and close off the outside air inlet immediately if the engine is cool enough. When the damper door starts to open the snorkel passage, remove the air cleaner cover, and read the thermometer. It must read approximately 55°C (131°F).
3. If the damper door is not open at approximately 55°C (131°F), the temperature sensor is malfunctioning.