A/C & Heat not working properly in Front works fine in Rear

My Front A/C and Heat are acting up in the Front but work fine in the Rear. The Front will work fine for a while but upon acceleration shut off. I am thinking this is a Front Blend Door Acuator (I believe they are vacuum controlled). If this is in fact the problem where can I locate it and is it difficult to replace? Oh 99 Expedition 5.4

I am having the same issue with my 03 Expedition. I thought I was going crazy, but when you accelerate it stops blowing but when you reach a "steady speed" it goes back to working again.

I am having the same issue with my 03 Expedition. I thought I was going crazy, but when you accelerate it stops blowing but when you reach a "steady speed" it goes back to working again.

got a 2003 exp and mind only blow on high in the front, the rear works fine, any help, thks.

My 1999 Expedition Eddie Bauer Edition blend door actuator was in fact electronic and had failed. The module consists of a motor which drives the blend door and knows the position of the door by the rheostat or potentiometer built on the board. That is what went bad on mine causing the A/C to not work properly in the front.

Sounds like a vacuum leak. If yours is vacuum controlled and you have manual controls, look for the tiny vacuum lines that come out near the heater core at the firewall under the hood. They are usually white and deteriorate from the heat. Chances are there is a hole in it somewhere between the firewall and where it connects to the vacuum tree. (Note: I don't have that model but my '96 Bronco is having the same problem and I've found at least 2 leaks so far and that hose was one of them.)