2002 T&C Air cond from driver's side vents is not cold

When using the air conditioning, the upper vents on the driver's side blow slightly warm air while the passenger side vents blow very cold. I've got both sliders on the controller all the way to the left.
Sometimes after about 20-30 minutes of driving, the driver's side vents will all of a sudden start blowing cold air. (but still not quite as cold as the passenger side)
Also, if I  slide the driver's side temperature slider on the AC controller back and forth from cold to warm to cold, sometimes after 6 or 7 tries, the left side vents turn cold.
Any educated guess as to whether it may be a either a flap or the controller itself?

U have a leaking condensor which is the big grill looking thing in front of the engine. The freeon is low so it will only coll hafy of the air comming is the driver side air is the furthest away so it is warmer. look at the front of the condensor on the passanger side lower corner  u will see wet spot.

I have the same issue with my a/c on my town and country....the passenger side blows warmerer than the driver side.  I have put in freon with leak sealer and everything worked fine for a couple of days then the freon ran out and we''re back to blowing warm air.  I had thought the leak was in the dashboard and hesitate to pull the dashboard out given the labor involved.   I''ll check the condensor in the engine.   I also hear in the rear right vent a hissing noise and am curious if there is possibility of a leak there or if this is normal?  
Thx. Bob 

I found out through my local mechanic that Chrysler had extended the warranty for the AC in this vehicle due to known issues. I took it to my dealer and they repared it at no cost to me.