MY AIR CONDITIONIER ON 97 FORD EXPIDITION BLOWS HOT AIR IN THE FRONT, YOU CAN TURN THE AIR OFF AND THEN BACK ON AND IT WILL WORK SOME TIMES FOR A LITTLE WHILE. SOME TIME IT WORKS OK FOR A COUPLE OF DAYS. WHEN YOU TRY AND RUN THE HEATER YOU GET COLD AIR IN THE FRONT, THE REAR AIR AND HEAT WORKS FINE.

Check the solenoid under the dash, mine seized and wouldn't switch the heat to ac, had to remove it an manualy open the door to ac, if your door is seized good luck most mechanics will tell you it's about a 10 hour job to do and about 400 bucks in parts for the box and whatever else they find wrong if you have the time to take your dash apart you can do it yourself but like I said most mechanics will want about 1000-1200 bucks to do the job.

The hot and cold air in the front is controlled by an actuator in the dash. The temp controller is working as designed because the back is working fine. You need to take to local shop to have the vent actuator or heater control box inside changed out. Then the tempaturer controller has to be reset. Good luck