I have a 93 Grand Am for my son. The car was not heating correctly the Drivers side will throw heat, but the passenger side blows cold air. It does not matter what setting you have it on. This past weekend we flushed and changed the Antifreeze in the car. If was very dark in color. We are still having the same problem. We need help on trying to figure this one out.
It is in the duct. Probably one of the doors. Check the vacuum lines and make sure none of them are torn, should be color coded. May have a bad actuator? *check and see if you can hear the door slamming open or shut when you turn the car on, and when you change settings.