73silververt

did all c3's have a fresh air door flapper top of cowl, mine does'nt, it has a/c, (73 base model) i have seen them for sale for 68-82, was it associated with a specific option, mine has a vacumn operated vent in lower right kick panel

7T1vette

I think they all had them. I would think all A/C cars would need them for the "MAX" A/C setting to work properly. Mine is a '71 and it has one; would think it to be the same on '73.

Manuel Azevedo

Not that it relates really to yours, but my 68 air car has the freash air door and the kick panel door

Easy Mike

AC cars have a flapper door tucked under the right fender top at the end of the windshield trough. Non-AC cars do not have the flapper door.

AC cars have a vacuum operated kick panel vent door on the passenger's side. Left side kick panel vent and both ball vents are closed off and do not route outside air.

For non-AC cars, both kick panel vents open and close from the console vent ***** and both dash vent ***** will route outside air.

The AIM shows the operating doors and their installation for AC cars. Also shows where the remaining vents are blocked off and not used.

Manuel Azevedo

partly true, the ball vents on the dash are used for the air conditioning on air cars, at lease they are on my 68. But I think you meant they are not vents which is true, just not blocked off but used for the air system.

Easy Mike

For AC cars, the vent ***** route cold AC air and will route outside air only when the AC controls are set to VENT (and maybe BI-LEVEL, can't recall exactly).

For non-AC cars, you get outside air through them.

LS7Vette

I have an A/C that the entire A/C system is being removed. I have the correct heater core cover from a non a/c car, dash ductwork, etc and would like to get both kick panel fresh air doors to work with the levers on the console. I think the right side should be easy enough to get working properly but was wondering if there is a way for me to punch out the left side. By the way I am getting a donor car to take any needed parts off of. Anyone know if this is able to be done?

thanks,
Ray

mrvette

on any vert, what you really want to do is seal off that opening, I just disabled the door mechanism so that it could stay closed, it opens if vacuum is removed from the control device....having it sealed shut and the a/c on permanent recirc is a huge help in keeping the car cool, remove the interior flapper door also....

as for adding astro vent, I wouldn't bother.....time waster....

73silververt

could someone educate me on how that flapper valve and the door in the kick panel work, by vacumn of course butwhat are there functions, do they work togeather? my 73 is defintely an a/c car but had some damage on passenger side of car i think some parts were not put back, anyone have a photo of a 73 showing cowl area with flapper valve

Mike Ward

If you talking about the flapper valve inside the hood (you mentioned 'top of cowl') this has no connection whatsoever to the heating or AC system.

The hood flapper was a whizz-bang failed attempt at cowl induction to boost performance.

73silververt

i know about the hood deal, this flapper valve is on top of firewall, shouldnt said cowl

Mike Ward

Not sure which flapper valve you're talking about then, got a picture?

Easy Mike

In a nutshell, on AC cars, the cowl flapper and kick panel vent doors open and close by vacuum depending on whether you want cooled AC air or fresh outside air in the cabin.

Purchase the 73 assembly instruction manual (AIM); it shows diagrams of the optional factory AC and the required parts.

Mashman

It really wouldn't make sense to have the door in the kick panel, and not have the fresh air door. The idea is for when you want max cooling, the air coming into the plenum would come from the already cooled air in the car, and not from the outside. So then the lower door is open, the upper door needs to be closed, or the whole intent of the door is lost.

Maybe there was a problem with the door not opening, so a prior owner removed it. My 72 is a bit different with the wiper bay, but the door is back a little ways, is it possible you just aren't seeing it? If it really is gone, I would just go down to the kick panel door and set it to remain closed at all times. I think you can do this by either removing the vacuum line, or the spring, I'm not sure which.

noonie

The upper flapper is only used in "Max air", it closes and the kick panel door (normally closed) opens for recirculating the cool air.
A lot of the flappers deform over time and don't seal well, so it you use the air a lot it helps to seal the upper shut and remove the spring from the lower to keep that door open.
Otherwise, you don't have to worry about it too much. Your choice.

Here is a pic from another thread.

73silververt

sorry for not identyfing the part in question correctly, i seem to be missing the plenum valve (flapper), still confused on function. it seems if flapper and or kick panel vent are open then you would be pulling in air from outside car (or least from inside fender or underhood) isnt air recirculated in the interior heating and a/c housing. maybe i will leave that plenum valve off, i see it in the aim and my firewall is missing the portion it would be mounted to anyway. damn this car is driving me crazy

Manuel Azevedo

You are right that the air for both vents comes from the outside only, But the lower vent is only outside air going into the cabin, the upper vent goes directly into the blower plenum.

7T1vette

One of the important functions of that cowl plenum door is to keep cr@p out of the plenum when the car is not running. That door closes without vacuum present and keeps leaves, bird 'doo', etc. out of the plenum. It may not work as well as we would like it to...but it works.

moonsteel

But but, whiz-bang is good for 1000hp

bigvette1

Is the vent door open when in vent position and closed when other positions?