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When the engine is not running, both flaps should be open.
With the engine running, the LH flap should close during cool weather (below 86*) and open when the engine warms up. This causes warm air to be drawn thru the LH exhaust manifold heat riser.
When the engine is running, the RH flap should stay closed until the intake manifold vacuum drops during full throttle operation.
This operation is described in your '84 FSM, pg. 6E2-121.
(The weather in my area never gets very cold, so I have disconnected my RH flap vacuum motor and plugged the hose to that vacuum motor, so both flaps stay open during normal operation. I'm therefore using both in-hood snorkles for best cool air flow to my intake system.)
To add to the above, the feed hose is connected to the inside vacuum port on the drivers side throttle body. (Port closer to the middle, the outside one runs the MAP sensor). I have seen it where people switch the connector with the balance port, the one in the middle, and plug the vacuum one. In doing that, the thermac system will not operate as there isn't sufficient vacuum. Also... it could just be disconnected.
If you disconnect it, be sure to cap the vacuum port. If you need to pass a smog test and the test requires a visual inspection, you'll fail unless you do a sneaky job of hiding your crime against humanity!
The OP's air cleaner housing may have already been modified like this! Or maybe it's just disconnected, either intentionally or unintentionally.
If you disconnect it, be sure to cap the vacuum port. If you need to pass a smog test and the test requires a visual inspection, you'll fail unless you do a sneaky job of hiding your crime against humanity!
The OP's air cleaner housing may have already been modified like this! Or maybe it's just disconnected, either intentionally or unintentionally.
Thats kind of what I'm thinking. Those vacuum diaphragms don't really ever fail. I thought one of mine were bad but someone had actually cut the rod off the one side.
