interesting. i have an 85 and my blower motor bearings busted. I removed the motor and put some ducktape over the hole where the motor attached to the housing. now, when i turn on the heat i get good heat when the car is moving above 10MPH.
on the highway? shoot...it's like i have a blower motor running back there!!! the ONLY problem is now the defrost motor in the front won't turn on...you know the little knob by the heater pulls? Any ideas? So I end up running the "fresh" air motor to at least blow cold air over the windshield.
then again, i'm in texas and it gets 32 degrees at the COLDEST.