83 H/O, when the car gets to temp and you turn on the heater and blower it blows outside air. No heat, is this mechanical or vaccume?
Thanks,
Adam PA

 

A cable runs from the control to a lever on top of the heater case. This controls the mixing door. That plastic lever broke on my 83 Regal. Possibly a plugged heater core? There's also a vacuum operated valve on the intake manifold. Feel for heat on the hose from that valve to the core.

 

Heater blend door behind the glovebox. Pull out the glove box insert to see it. Then read these threads. This is a common problem on the 1978-1988 A/G-body and 1977-1990 RWD B/C-body cars.

https://classicoldsmobile.com/forums...2-no-heat.html

https://classicoldsmobile.com/forums...lows-cold.html

https://classicoldsmobile.com/forums...questions.html