I am taking mine of to paint it ,and I noticed that when I apply vacuum to it ,the flapper raises up ,but does not come back down.When I take the vacuum hose off of ,I guess it is a check valve, it comes back down.
Does this sound right . Will the flapper come down when it gets hot? Can I just take the check valve off?What will be the best way to have it?

Thanks
Dave

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81 Dodge D150
It looked easier in the book .

There is a thermostatically controlled valve in the vacuum supply line to the flapper diaphragm. The valve is the little round disc mounted on the air cleaner. When the valve sense the air temp in the air cleaner is below a certain point, it permits vacuum to be applies to the flapper diaphragm and for the flapper to open, permitting heated air to enter.

Thanks Reed, but the check valve that is between the sensor and the actuator seems to be (one way), and the only way I can get the flapper to go down is to unplug the vacuum hose from the check valve.I think I read somewhere on here that you could take that valve off,and just want to make sure.


Dave

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81 Dodge D150
It looked easier in the book .

Yup, it is optional, but I can't help thinking that Mopar put it on there for a reason. What that reason might be, I have no idea.

The check valve was a TSB component in about '78 or so, later added to production. It improves cold-engine driveability. The door will come down (slowly) once vacuum's released from the input side of the check valve. The idea is to keep hot air flowing to a cold engine; without the check valve if you stomp the gas and manifold vacuum drops, the flap door drops and lets in cold air instead of hot, and the engine may hesitate or stall.

No real reason to delete it.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks, I finally found a lighter , and heated up the sensor a little , and the flap came down slowly, so i take it , it is working


Dave

_________________
81 Dodge D150
It looked easier in the book .