When the heater is set on defrost, the Drivers side blows somewhat warm air (not hot), and the passenger side blows cold air. When set to vent, some vents blow cold and some are warm. Finally on the heater (floor) setting, same thing, drivers is warm, passenger is cold air. What could cause this? I am going to check the coolant level and the thermostat but not sure what to check after that. This is something I would really like to figure out without taking it in being that it is xmas time.
Any help would be GREATLY appreciated.