99 Expedition with front and rear a/c

Hi, I am relatively dense when it comes to cars and I need some help. I have a 99 Expedition XLT with front and rear a/c. The front air blows warm and the rear air cold. I tried taking the knob off the front and turning the temperature with a pair of pliers to make sure the knob wasnt stripped, but it was fine, it is all the way over to cold (blue). Are the two on seperate systems or does anyone have an idea what may cause this?

A lot of people have been having this problem; check out this:

http://www.fordforum.com/m_1873/tm.htm

I have the same situation on my 99 Expedition, can you let me know if you find out the solution for this?

Try the link I gave in the last post, then go to planefella's link. good luck

Yeppers , As you said seen this happening a lot , Like they say the more things change the more they stay the same. I remember this being a common problem on the F-Series back in the late 70's an early 80's with the lil door that shut off your outside air for AC -- HUMMMMMMM