Jeep: Climate Control Problem, jeep cherokee sport, vacuum mode

Question
 I have a 2000 jeep cherokee sport 6cylinders. I just got it a couple weeks ago, and the only problem is the CLIMATE CONTROL. The blower switch and the temperature are working fine. The only problem is the center button, i don't know exactly how you call it, is blowing air in only one direction, even when i turn the button. I ask to my friend and he say that maybe the problem are with some air hose. Could You please help me with that problem? Thank you.

Answer
Archie,

Most times, this is a vacuum problem. Normally, the default is usually with the system reverting to defrost mode -- all air directed to the windshield. If so, then I would check for vacuum supply to the control head, and the operation of the rotary valve.

After working on many of these, it's usually an issue with the vacuum mode actuator, mounted on the side of the A/C-heater case. They often pop out and get lodged in a position that they can't operate in. Most times, it takes a new actuator, which, consequently carries an updated part number (jeep hasn't issued a TSB on this, unfortunately).

Whatever the case, good luck!