I recently replaced the super six air cleaner on the dart with a less ratty-looking one. Problem is, the sensor seems to be NFG on it. With the car cold, I started it with the air cleaner lid off. The door stayed shut (cold air position). When I placed my finger over the "standpipe" (for lack of a better term) on the top of the sensor on the air cleaner, the door went to the up position (heated air) and stayed that way after I removed my finger. When I then put the air cleaner lid on, the door gradually closed(over two or three seconds, so I assumed it was a pissed sensor.

I then swapped the old air cleaner (which was in perfect working order when pulled) for the new one. Ok, now I get heated air on start-up, but the door never shut when the car warmed up. Even when I disconnected the vacuum signal (pulled both hoses off the sensor). Once I disconnected the hose from the actuator on the snorkel, the door shut. There is what appears to be a valve (small canister) in the vacuum line between the sensor and the actuator. I looked it over and ensured it was plumbed the right way around (nipple labeled "sensor" getting it's signal from the sensor). I then checked the valve itself. When vacuum is applied to the side labeled "sensor", the thing flows freely, but when vacuum is applied to the other side, it holds and will not bleed down.

I checked the hose from the sensor to the valve when the car was hot and the signal is much weaker than it was at start-up, so I'm 99% sure the old sensor is still good, but I'm stumped as to why the valve in the line won't allow the door to close when there's no vacuum going to it. How do I fix this? I'm stumped.

On the plus side, I know the actuator is still in good nick as it takes a lot of force to get the door closed until I remove the valve from the line.

Thanks in advance,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

That check valve in the line between the sensor and the actuator was originally a TSB part (later incorporated into production) to patch up a cold-engine hesitation and stall problem on '70s and '80s cars tuned on the ragged edge of too lean to squeak by new-car emission certification standards for market eligibility. Try removing the check valve (run a continuous vacuum line from the sensor to the actuator) and see if it works correctly. New sensors have been drying up on the retail market, but I have several on the shelf; send me a PM if you need one.

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

Should the check valve eventually bleed down? I guess what I'm asking is whether mine is toast or not.

Thanks,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

Yes, it should slowly bleed down.

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

I went ahead and removed the check valve from the picture and it seems like everything is as it should be. One final question; What keeps the incoming cold air from cooling the sensor to the point it opens the door (to the heated air position)?

Thanks,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

Nothing.

It will mix the air (heated/unheated) by the position of the flap. If the air gets too cold, the flap will let in more hot air; too hot, more cold air.

When driving it will probably be somewhere between fully open and fully closed.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

The sensor works to keep the air temperature to between 80°F and 100°F at the carburetor air horn — note how there's no line of direct airflow between the snorkel and the sensor, so there's no cold air blast to "fool" the sensor.

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

Hence the deflector just inside the air cleaner, yes? Seems obvious now.

Thanks again,

Nat

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1970 four-door Dart, 225/A-904/2.45 gears. 0-60 in twenty three minutes!

Why not these sensor from other vehicles like carb 2.2? You still can find them, and mine still works.

Cheers, Wizard

All the Mopar sensors, right up thru the 1990s (after which they stopped being used) are discontinued both in the aftermarket and from Chrysler.

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