Thermostatically Controlled Air Cleaner

Vacuum Motor Testing:

***UPDATED BY TSB NO. 9003007, JUNE 7, 1990

VACUUM MOTOR AND HOT AIR CONTROL VALVE TESTING

1. With engine not running, connect vacuum motor hose directly to vacuum nipple on intake manifold.
2. Look through air intake snorkel of air cleaner and ensure that hot air control valve is completely closed, blocking off the hot air hose.
3. Start engine and run at idle. Check that the hot air control valve is now blocking off the ambient air intake and open to the hot air hose.
4. Check that the hot air control valve opens and closes smoothly.
5. Ensure that vacuum motor holds vacuum and does not leak down.
6. As an alternate test method, use a hand vacuum pump to conduct the checks previously described.
7. Replace the vacuum motor and hot air control valve if they fail the above tests.

THERMO VALVE TESTING

1. Remove air cleaner from vehicle.
2. Attach a thermocouple-type thermometer to thermo valve.
3. Reinstall air cleaner after allowing it to cool.
4. Start engine and check the following:
a. look through the air intake snorkel and check that the hot air control valve begins to block the cool air intake side when engine is started.
b. take a thermometer reading when the valve begins to open to outside air.
c. take several temperature readings to obtain an average value since readings may vary each time the test is made.
d. if average temperature deviated from the range of 38~-44~C (100~-111~F), replace thermo valve.

Hot Idle Compensator:

HOT IDLE COMPENSATOR TESTING

NOTE: Never touch bimetal temperature sensing portion of hot idle compensator.

1. Remove air cleaner if necessary and attach a test hose to hot idle compensator.
2. With a suitable thermometer, check temperature in immediate vicinity of compensator.
3. Blow on the hose. If the temperature is above 46~-52~C (115~-126~F), air should pass through compensator. Air flow should be blocked if temperature is below specification.
4. To facilitate testing, a hair dryer may be used to raise the temperature.
5. Replace the hot idle compensator if it fails this test.