D50 4WD L4-156 2556cc 2.6L VIN 7 2-bbl (1982)
Thermostatic Air Cleaner: Testing and Inspection
Mechanical System
1. Visually check position of air control valve. If underhood air temperature is below 41° F, the valve should be in the full heat position. If
underhood air temperature is between 41° and 108°, the valve should be in a position to admit both cold and warm air. If the underhood air
temperature is above 108° F, the valve should be in the full cold position.
Vacuum System
1. Check that heat cowl to air cleaner and all vacuum hoses are properly attached and in good condition.
2. With cold engine and ambient temperature of less than 84° F, air control valve should be in up position.
3. With engine warmed up and running, check temperature of air entering air cleaner. When air temperature exceeds 113° F, the air control valve
should be in down position.
4. Remove air cleaner from engine and allow to cool down to under 84° F. Apply 15 inches (380mm) Hg. vacuum to sensor and check that valve is in
up position. If valve does not rise, check vacuum motor for proper operation.
5. To test vacuum motor, apply 10 inches (250mm) of vacuum using tool C-4207 or equivalent. Valve should be in full up position. If vacuum motor
fails to operate properly, replace air cleaner housing assembly.
