Why does air come thru my vents when everything is off?

[400sforever]

I'm not experienced with anything under the dash on my 74 charger se because I've never had to take one apart, but when cruising down the road with all my a/c and vent systems off, air still comes thru the vents like the fan is running wide open. I'm assuming there must be a door that isn't shutting or something. When switched to defrost or floor settings, the air flow doesn't change to either, just keeps coming out of the vents. Anyone know what I need to fix? Thanks!

[myk]

Like you said, there could be a door or something not shutting all the way, allowing air to still come inside the cabin.  Also, keep in mind that some ventilation systems in cars will always have even a little air coming inside because they're not perfectly sealed; at least not in the cars I drive.  I'm sure a newer car with an upper scale interior and appointments (BMW, Mercedes, Cadillac) might have a better contained ventilation system...

[Mytur Binsdirti]

The foam gaskets could have disintegrated.

[Mike DC]

 
Seems like every car/truck does this to some extent.  Annoying.

 

[myk]

What I've noticed is that even with the AC or heater motor off, air will still come in either cool or warm, depending on where the control knob is set.....

[400sforever]

Does anyone know why it won't switch from vents to floor to defrost? I'm thinking that there must be a vacuum line unhooked maybe?

[XH29N0G]

It is not that there is a separate 'vent' pull cable that is open, is it?  I have one on my 70 under the dash on the left of the wheel.  Don't actually know if it runs through the same ducts though.

[1973rallye]

Does anyone know why it won't switch from vents to floor to defrost? I'm thinking that there must be a vacuum line unhooked maybe?

Had similar issues with both 73's.
On one the cable clip came off and the cable was not connected to the controls.
On the other the vacuum lines had somehow been disconnected under the dash.
Both simple fixes which result in everything working fine on both cars.

[Baldwinvette77]

every car allows air in, even today, the doors on the evap unit either don't fully close or the factory drills holes in the door so fresh air is constantly going through the car..   

[400sforever]

I'll have to check my cables and vacuum lines under the dash. Since my car is an a/c car it doesn't have the individual vent cables

[polywideblock]

don't have H41 on your fender tag do you ? 

[400sforever]

I'd have to check the tag. What code is that for?

[polywideblock]

strato vent 

[400sforever]

Oh ic ya my se doesn't have that code

[PlainfieldCharger]

I thought the AC cars cycle the fan on and off with the thermal time delay that is on the bottom of the AC Box

[myk]

every car allows air in, even today, the doors on the evap unit either don't fully close or the factory drills holes in the door so fresh air is constantly going through the car..   

Might be a safety feature...

[ODZKing]

Does anyone know why it won't switch from vents to floor to defrost? I'm thinking that there must be a vacuum line unhooked maybe?

If you have a factory A/C car there are vacuum actuators in there. at least 2 if I remember that open and close the doors. If the line/hose has a crack in it or the actuators are stuck the system won't work properly.
Here is a pic of my 73, should be the same.

[johnnycharger]

http://www.dodgecharger.com/forum/index.php/topic,70841.0.html

Maybe helpful to shut off the heat....