OK...so I got my car about 3 years ago and although it runs and looks great, obviously there are many things that require attention on a 30 year old car. I have noticed that warm/hot air is blowing in to passenger compartment from under the dash. (Almost unbearable to drive on hot days) All switches/levers are in OFF position on the climate/air conditioning controls. I was told that the vents under the dashboard are controlled by a vacuum line that opens and closes when the controls are moved thru the heat/air conditioning controls.

Can someone please point me in the right direction to find the correct vacuum line that controls the vents leading into the passenger compartment to see if the vacuum line is broken or damaged?

Thanks for all of your help in advance !

 

You can't stop the air flow no matter what in most GM cars
with a/c. Its a ancestor of the old GM flo-thru ventilation of old.

It drives me crazy on my 84! My new Impala is the same.

Funny my dads Dakota truck when you shut the fan or controls
to off it stops all air flow.................