Thermostatic Air Cleaner: Testing and Inspection

1. Ensure all vacuum hoses and the stove to the air cleaner flexible connector are properly installed and in good condition.
2. With engine cold, and ambient temperature in the engine compartment below 100° F, the heat control door in the snorkel should be in the up (heat on) position.
3. With the engine warmed to operating temperature and running, check the air temperature entering the snorkel or at the sensor. When temperature is 105° F, or higher, the door should be in the down (heat off) position.
4. Remove air cleaner from engine and allow it to cool down to 90-95° F. Using a suitable vacuum pump, apply 20 inches HG vacuum to the sensor; The door should be in the up (heat on) position. If not, check vacuum diaphragm.
5. To check the vacuum diaphragm,apply vacuum directly to the diaphragm bleed valve in the line to control the vacuum inserted in the line between the gauge and the vacuum source. Apply 20 inches Hg. to the diaphragm and close off the line. The diaphragm should hold this vacuum for approximately five minutes. Release the vacuum then with the use of the bleed valve. increase the vacuum slowly and observe the operation of the door. The door should lift off the bottom of the snorkel at 5 inches Hg. and reach the full open position with no more than 9 inches Hg. If it does not, the diaphragm must be relaced.
6. If the diaphragm performs properly but proper temperature is not maintained, replace the sensor and repeat procedure.