I have a problem with a 99 expedition that the rear air works fine but the front air works sometimes and other times blows hot air. Any information will be greatly appreciated.

 

Well they're 2 totally separate systems. So the electric driven one is fine and your main engine driven system is leaking. Best bet is to take it to a good auto AC place and let them find the leak. Then decide if you can do the work yourself or not.

 

Moon got to Misc, Heating cooling, EB Expedition blend door fix. This will give you insight on the problem. I just fixed mine the weekend. "PITA"

 

moonjabber,

Iceman8984 is correct, more than likely it is the blend door. The Expy with dual air has One compressor and two evaporators with blowers. The front AC evaporator is under the dash and the rear evaporator is in the left rear cabin behind the interior trim panel. When you move the temperature controll on the dash warmer the blend door moves from full AC (all air from blower passing over the evaporator) to allowing some of the air to pass over the heater coil. This mixing of warm air and cold air is what allows you to select a warmer temperature coming from the AC vents. Sounds like the front blend door is staying in one place allowing more or all warm air from the heater coil to enter instead of air from the evaporator.

Hope this helps