deltaroads

I have an '86 Cutlass and the heat is not working, I believe it's the air blend door because it's got antifreeze, heater core is not stopped up, and the blower is working. The floor blows somewhat warmer than the air outside so I know it's heating a little, but the defrost blows very cold and the dash vents don't blow at all. So anytime I turn on the heat the cold air from the defrost vents cancels out any warm air from the floor. I need a haynes manual but it's on order and IT'S COLD NOW!!!

J-(Chicago)

My guess is that your heater control valve is not functioning correctly. It opens and lets coolant into the heater core.
I have a few of them laying around I could sell, if it ends up being your problem.

Saw just the round head off of your heater control valve, and clamp your heater hose onto the remaining stalk sticking up out of the back of the intake. You should have heat then.

You won't need to replace the valve until it's time to put the AC on.

J-(Chicago)

It looks kind of like this one.

deltaroads

Anybody have a good description of where that air door is?

J-(Chicago)

If you pull the glove box, It should be there.

BlackGold

It's easy to check the heater control valve operation. Warm up the engine and place your heater control on anything but "off" (just as well put it on "heat") and your temperature control anywhere right of "cold" (just as well put it all the way to "hot"). Now feel both the supply and return hose for your heater core (under the hood, at the firewall). Both should be hot. If cold, your heater control valve is bad, or your dash control unit is not sending the right vacuum signal to the heater control valve. If the hoses are hot, then it's time to look at the blend door.