2005 XLT A/C does not blow when driving only when stopped

[kd7yar]

On my '05 XLT Explorer my wife discovered today that while driving the A/C from the dash practically stops blowing while driving, but when she stopped at a light the air would begin blowing through the vents again. When she started to drive again it again all but stopped.
The A/C in the back worked as normal the entire time adjustable by the controller in the back seats.
Any ideas on what may be going wrong?

Thank you!

 

[scucci]

Look for a vacuum leak.

 

[mrau92me]

scucci is right about it probably being a vacuum thing. I had the exact same thing last summer on my '02 Mountie. While changing the spark plugs & wires just prior, I unknowingly unplugged a small vacuum hose while wrestling with the wire routing behind the alternator area on the passenger side of my 4.0L. If you've had or done any work on it recently, start by lightly tugging on your vacuum hoses and see if any are loose. If you don't find any, crank it up and listen for hissing or whistling which will help you locate loose connections or leaks.