I've got unwanted hot in my '84 even with temp lever in cool. This is undesirable in central FL with no a/c. I can see the heater core closed off by the dash lever but warm (well above ambient but not quite hot)air still flows.
Does anyone know the fresh air source for fan?
I shoe-horned in headers that are pretty close to the fire-wall on pass side and suspect it might be the heat source.
I hate unnecessary dashboard surgery so I'd like to hear from the troops in the field before beginning dismantling.

Air is received from the cowl panel. Should a gasket on the firewall to seal cowl panel from the engine compartment.

May have to install a water cut-off valve in the heater hose from the engine. graemlins/thumbsup.gif

Welcome to the Club graemlins/waving.gif

It's the nature of the beast. Try to seal off the hood in the back the best you can. I always had warm air coming out of mine, unless it was below 60 deg.

If it doesn't turn out to be the heater, you can put some insulation on the inside under the carpet running up on to the firewall to reduce the header heat. Good Luck

i had a similar prob, underneath the center console in front of the gear shifter is a rubber grommet/plug where the transmission cable comes into the car, mine had to be replaced and the grommet wasnt properly seated thus allowing engine/transmission heat to enter the car. just a thought, you might wanna check it out..

Ah yes, my '84 Buick Skylark did this...The Summers were aweful, hot air kept pouring out.

I ended up re-sealing the flapper doors in the heater box. This cured the problem.

Another solution is to hook up another switch for the fan. See, the blower motor runs constantly (maybe they didn't in Camaros, but I'm sure they did in most GM cars), so if the flapper door leaks hot air, hot air will blow out.