Ford Repair: 1998 Mercury Sable heat doesnt work, vacuum leaks, mercury sable

Question
I recently purchased a 98 mercury sable and the a/c works great the bad part is that when you try to turn on the heat it seems the blower motor is working because you can feel it coming from the vents but you only have cold air no hot, i checked all fuses and flushed out the heater core and radiator, the heater core hoses are both hot so the coolant is passing through the heater core and you can hear a kinda slamming noise when you switch the control from cold to hot so i am assuming that is the blend door, i couldn't find any vacuum leaks anywhere on the car any ideas on what it could be before i go tearing the dash apart to investigate farther??  Thanks Shaun Mason

Answer
Most common failure for this symptom is the blend door electric motor. In rare instances the door itself can crack or break. On your Sable this motor is not bad to replace or remove. Take off the panel under the dash on right side, below glove box, then pull out the console trim on the right side, front of vehicle. You can access the door motor now, it is white, maybe 3 inches square, with one connector and 4 screws. Once you have the motor out, you should be able to see the socket the motor shaft fits into, if it is cracked a lot more work is in store. You can also move the door from this point, make sure it moves both directions. I have found pens or other slim objects in this area before which prevents the door from full travel.

Good luck.