i am haveing small problem with cold air blowing thru my vents with the heater on
the heater works good but is still cold due to the fact that there is cold air coming outa hte vents LOL i thought that it possible that the fresh air vent is not closing ?
to the outside any ideas before i dig into it ?

 

there are two hoses that run to the firewall on the passenger side. Once side is your HOT flow of coolant, the other side is the return. Verify that both are equal temp or hot, and give it a squeeze for pressure on both sides. You want to eliminate whether or not it is plugged, it's simply a small radiator inside the cabin.

If those check out, then there is a switching valve thats controlled by your heater control. It opens or closes to allow more or less flow through. I'm not exactly sure on specifics, but a simple search will give you an answer. I think trochoid or rx7doctor explained it once but i'm too lazy to search, plus im heading out the door. G/L

 

Do you have the slide controls or the push-button type for the settings.
And if you put it over to defrost does it blow hot air towards the windshield?

 

Where is the cold air coming from? I know the control on dash vent on the far right side often breaks, and cold air comes in from there.

Welcome to the forum and the Darkside. In my sig line is a link to the online FSMs, carb manual, etc. Enjoy.

 

mine does this only on the passengers side.......then my buddy noticed air coming from above his feet by the ac unit. i removed my AC pump and lines up to the firewall and i think when i was takin the lines off i messed up the ducting cuz i noticed it wasnt connected all the way so i taped it and it helped a tad. but somtimes it gets either really hot or just a lil cold.

 

I've noticed this too with my 85 GS. Heater works fine, but the center vents over the controls continue to leak cold air into the cabin. Its not a whole lot of cold air coming in, but when the temps dip down into the teens you know you'd be a lot warmer if that cold air wasn't being added to the mix...

 

it may be stupid but I fell for this one, the switched under the side vents (if thats the vents leaking air) in one position they draw air from outside, in the other they do as the controls do.