it could be a couple of things the most common problem is the blend door, it controls the air from the blower to the heater core or evap. can you change the air comming from the floor to vent to defrost? if so its the blend door not the mode doors, im not to familiar with the contour case and duct system but its probally electronically controlled vaccum , so theres either a vacum problem or the microprocessor isnt working right, i know that the blend doors are prone to braking so that might be the worst of your problems. and its probally not a problem with the car being low on collant , since its not blowing warm air atall.
