System Testing

Fig. 83 TAC air door operation. Engine off:

Fig. 84 TAC operation. Engine running, temperature below 85 F:

Fig. 85 TAC operation. Engine running, temperature above 128 F:

FUNCTIONAL TESTING

1. Remove air cleaner cover and install temperature gauge tool No. J-22973 or equivalent, as close as possible to temperature sensor.
2. Install air cleaner cover. Do not install air cleaner cover wing nut.
3. With engine ``OFF'', check damper door position through snorkel opening. Snorkel passage should be open, Fig. 73, if not check for damaged linkage.
4. Start and operate engine at idle. With air temperature below 85° F, snorkel passage should be closed, Fig. 84. When damper door begins to open snorkel passage, remove air cleaner cover and check tool reading. Reading should be between 85° F and 115° F.
5. With air temperature 128° F, damper door should be fully open, Fig. 85. If not check linkage for damage.
6. If damper door does not close completely or does not open at correct temperature, note the following vacuum motor check:
a. Switch engine ``OFF'' and disconnect diaphragm assembly vacuum hose from temperature sensor.
b. Connect a vacuum gauge and apply 7 inches Hg to vacuum diaphragm assembly through diaphragm hose. This can be done by blowing into the diaphragm hose.
c. Damper door should completely close snorkel passage when vacuum is applied.
d. If damper door does not close, check linkage for damage and diaphragm for a vacuum leak.
e. With vacuum applied, bend or clamp diaphragm hose. Damper door should remain in closed position. If not, replace diaphragm assembly.




VACUUM MOTOR TEST

1. With engine off, look into snorkel to be sure the valve plates are open.
2. Start engine and observe valve plates with engine idling. If equipped, the left plate will close immediately, regardless of temperature.
3. If the temperature in the air cleaner is below 90° F., the right valve plate will also close to outside air. With temperatures above approximately 100° F., the valve will remain open.
4. If vacuum motors fail to operate with vacuum directly applied, replace motor.

TEMPERATURE SENSOR TEST

1. With engine temperature below 85° F., tape a thermometer in air cleaner.
2. Install air cleaner cover and start engine.
3. When cold air door starts to open, remove air cleaner cover and check temperature. If temperature is below approximately 85° F., sensor must be replaced. If hoses have been removed from connectors for any reason, it is very important that they be correctly positioned for proper operation.