Rear AC doesn't cool

For the last 3 or 4 years my rear ac hasn't blown cool air. The front is fine. From what I can gather it sounds like it is the expansion valve causing the trouble. What does it sound like to ya'll?
Thanks, Marc.

Yep, it's the rear expansion valve. You need to have it either cleaned or replaced if necessary. Once you have it out, make sure you flush the lines, there might be some other junk in their that can plug it up again. I once made the mistake of not flushing and I ended up reversing my problem. I had cold air in the back and lukewarm air in the front.