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Just pulled the heater box out of my 69 , to install a new heater core , and thought I'd check the vacuum actuators with my mighty vac, the small one works fine, but the large one on the end works in one direction but not the other. I can easily get a replacement but I can't understand how it could only work one way?
When you are testing no other hoses are connected to the actuator other than the pump, correct?
The actuator has to exhaust/vent through one port or another.
Example, applying vacuum to the bottom port should extend the arm and whatever trapped energy on the top side of the diaphragm HAS too vent out the top port and vice versa.
Also, extend the actuator arm all the way out and inspect the witch hat seal for defects.
A spare of mine had a sealing issue I was able to repair with vacuum grease at the base,,.
Defrost vacuum actuator question
