I recently replaced my heater core, that part works fine. However, it looks like the previous owner of my car tried to do the same, and gave up. (It was totally disconnected) Anyway, when I remove the panel that is above the passenger footwell, I can see the heater core holder box. I'm pretty sure there's supposed to be something around this that directs air into the heat ducting - right? When I turn my heater on the controls work, and I can hear flaps open or close, and the air is diverted into these locations, but only come out very very slightly, The rest blows out at the floor by the passenger's feet. Does anyone know what part I'm missing? It's an 85 IROC-Z28 and I can't heat up in these sub-freezing Michigan winters!

 

When you move the TEMP adjustment on your heater controls you are moving the door flap to allow outside air into the system..... that control is operated by a cable and you can hear the door flap open and close as you use the control.

The air delivery (or mode) is Vacuum controlled. there is a vacuum hose running from the firewall area of your engine bay - thru the firewall - and into the heater system. It sounds as if either the vacuum part of your heater system is the problem.

The heater system vacuum line in the engine bay may be disconnected, It might be pinched shut, or the vacuum "disk" or connection on the heater control itself could be bad.

You mention that the system was serviced in the past - and that air does come from the propper locations,.... but just a little bit. It is possible that the system was not re-assembled correctly or that there is something stuck in the box causing the vacuum operated doors to not work properly. Mice are known to like living in the heater boxes of these cars and it's possible they started building a nest in the box and that crap is causing the doors not to open/close all the way.

 

Thank you for the reply. I know that the hot/cold slider is cable controlled, and that the direction switches are vaccuum, and my system appears to work properly in this regard. The problem really is that the air all blows right down into the passenger's footwell. Like there is a piece that should be there to block that air and force it into the rest of the ductwork. I'm not sure. I'm going to continue to try to figure out what's going onunder there, and I do thank you for the input.

 

this happened to me a few weeks ago.my problem was the same and it was that triangle plastic piece on the left side of the box,the flap pivots on this piece and mine is broken trying to get it out.i dont no if that helps but that was my problem good luck.gm no longer makes this part and i only have one junk yard around here and they wont let me take this piece which sucks.maybe someone here has one

 

I'll look into that for sure, thank you.

 

whoever tried to do it before you, cut a hole in front of the core instead of removing the cover and doing it right.

when i did mine, there was a rectangle piece cut out and hot glued back in.

cover it with something and glue it in place.