what's the pass. foot vent do?

[mike weyman]

i want to cover the foot vent over with silicone and plastic to close it off.it's too much of a p.i.t.a.to change the gasket so i just want to stop the flow without harming the workings,so i was just going to cover it with plastic and glue the edges.
is it part of the a.c.? exactly what does it do???

 

[Bob Chadwick]

The door in the vent moves and changes between fresh air and recirculation mode. I can't remember which position is fresh air and which is recircualtion.

Several people have posted about sealing it up. All it does is force the vent system into one mode or the other. I rebuilt the gasket and it wasn't too bad. If I were going to seal it up I would make sure that I figured out which position is fresh air v. recirculation and close it up in recirculation mode. In fresh air mode it pulls air from the outside and can be a source of heat in the cockpit.

I've posted some more detailed information with pictures on my web site.

 

[mike weyman]

by definition recirculated air must be from inside the car,therefore the closed position is most likely recirculate, there is no a.c.left in the car so it won't matter in the sense that i will not be cooling air to put outside.

i will seal it separately without giving into just calking it shut ,someone down the road may want to re-install the air conditioning.
thanks for thr response

 

[Bob Chadwick]

That is a two part system with another flapper up above. If I recall correctly, in recirculation mode the flapper up above closes and that door is actually open. This prevents air from being drawn into the system on top and draws the air from the inside of the car. If you close it you will be forcing it into fresh air mode and possible drawing hot air into the car.

 

[mike weyman]

what if i took the top air hose and joined it to the bottom one and let it suck itself to death? ...

seriously, i don't think the top vent is reachable in these things is it?
i got the shifter console in tonight so the side covers aren't far off and i would like to have this adressed before i get to that point.
Does anyone have a chart or anything wich tells wich does when??

 

[JohnZ]

In normal operating mode, the upper door is open (to admit outside air into the evaporator from the plenum in front of the windshield), and the lower inside door is closed. In "Max" mode (inside air recirc), the upper door is closed, blocking off air entry from the outside, and the lower inside door is open, to provide a return air path from the inside of the car to the evaporator. Recirc mode will cool the inside of the car down sooner, but if you lock it in that mode, you won't get any fresh air in the cockpit.

 

[lucky76]

i want to cover the foot vent over with silicone and plastic to close it off.it's too much of a p.i.t.a.to change the gasket so i just want to stop the flow without harming the workings,so i was just going to cover it with plastic and glue the edges.
is it part of the a.c.? exactly what does it do???

On my 76 I've always found that the fresh air was hot coming down from the windshield area so I changed the vent so it's closed all the time regardless of the settings on the ac/heater control. I have a new ac compressor, lines, and dryer but I don't plan on install them any time soon. I don't drive mine with the tops on anyway except in the winter.

You can see the vent and vacuum diaphragm unit down below the passenger side windshield wiper arm. Remove 3 screws and work it out.

I removed mine and the edges of the flap are brittle and pealing off so it doesn't close air off very well. This is a normally open vent (with no vacuum applied it's open). I took the cotter key out of the rod, pushed the rod all the way back, drilled a new hole and put it in the new hole. It's now permanently closed so no more hot air can come down into the car. That is as soon as I can find something to make a new flap and bolt it to the old one or cover the complete hole with, a piece of plastic or something. I've searched for this part in all the catalogs but haven't found it anywhere. Guess they don't sell it. Who would ever think after 28 years a piece of plastic would get hard and fall apart. Guess I'm lucky anything works on it.

Lucky

 

[mike weyman]

i tried getting the flap out tonight but i could not get it to lift off the bottom pivot.i did manage however to totally destroy the foam stripping around it.i popped the pin on the air powered thingey arm so that it is no longer controlled by anything,next i will seal off the bottom door with silicone.it is almost rare to see temps in the nineties here, more like sixties or seventies,so i don't think i'll ever hook up the a.c.again.

can anyone forsee any problems by closing this vent off?? i seem to be past the point of no return now anyway, but i can if i have to.
did anyone else block off the lower vent?? did it work??

 

[Bob Chadwick]

Mike,

It won't create any problem. You just won't have recirculated air. I didn't notice where you're from. Unlike here in Georgia, a little hot air is probably a good thing.

Bob

 

[jdp6000]

If you are having an issue with hot air getting into the cockpit I don't think what you are doing will solve anything.

There is another flap in your heater box that diverts hot an cold air. The seal on that one is usually the problem.

Jim

 

[mike weyman]

i am re-assembling the interior,i have never had it on the road so i don't know if i have a heat problem yet, but the gasket is bad tho,and i heard so many speak of this vent letting heat in.

bob, we usually only hit about 70-75 here, but believe it or not it's been in the high 80's this week,we usually don't see that in nova scotia till july.