Ranger 4WD V6-245 4.0L (1991)
Thermostatic Air Cleaner Vacuum Motor: Testing and Inspection
Air Door Vacuum Motor Test
1.
Verify that the air door is in the closed to heated air position and that the vacuum motor stem and the air door are connected, by looking up into
the snorkel.
2.
Remove vacuum hose from motor, connect a vacuum pump, and apply 10-15" vacuum.
Air door should be in the open to heated air position and must remain so for two minutes with vacuum trapped. When vacuum is released the door
should move to the closed to heated air position.