Cadillac Repair: 1991 cadillac seville, heating, 1991 cadillac seville, cadillac seville

Question
Hello Kevin,
I have a 1991 Seville, and the heating don't work very good, I get heat coming out only from the vent on the top of the dashboard, all the other vents, drivers and passengers side is no hot air coming out. But it blows OK on all the vents when the A/C is in use,Can you help? Do I have to replace the 4-seasons A/C Heater control, and where is it located? Thanks

Answer
Ben,
There's a vacuum-operated door that directs the air up to the defrost vents by default (in order for it to hit the floor, the vacuum actuator needs to move). The problem could be the vacuum source to the actuator, the hose, the actuator, or even the door itself. Start by seeing if the vacuum hose is connected and has vacuum present when heat is selected.