change the cabin filters
It appears your blower motor is not working correctly on your 1980 Cadillac Coupe Deville. The vents are for both AC and heat. You may also be losing vacuum pressure. If you cannot find the source, your mechanic can help you do so.
could be a leaking heater core ( Steam ) . Depends on WHAT KIND OF SMOKE. Is it steam or smoke. Smoke like something burning could be oil. electrical, etc
The heater core has failed.
The blower resister is not supposed to be grounded. The smoke may be steam from a leaky heater core.
Smoke could be coming from the vents of your car for a number of reasons. You may have an internal car fire.
The moveable "baffle" inside the dashboard is not redirecting the air flow as it should. It's operated either by vacuum or an electric motor, in either case, repair is going to require the removal of the dashboard.
Check for a plugged evaporator remove fan motor under hood and see if evaporator is plugged
I'm having the same problem with my GrandPrix, there's a website that may help you out a bit too, www.2carpros.com
ur electronic climate control (ecc) programmer is faulty need to change it and the vaccum harness to the upgraded one. by the way its on the passenger side under the dash.
actuator under center of dash is bad
Is it smoke or is it atomized freon leaking from the AC system? If it fogs the windshield and smells funny, you may have a leak in the AC/Heater system.