I've got a 2003 3500. When I run the airconditioner it initially runs fine...as it runs it seems to have something freeze up and the airflow decreases until nothing is coming out of the registers. If I run the heat for just a moment or two air flow resumes. Also, when I park it after running the ac I get quite a bit of water dripping out under the truck...I've enven had a drip or two on the passenger side interior. Where is this freezing up? How do I fix it?

Thanks...I look forward to hearing from the crew here.

 

first off check to make sure your drain tube is open, no dirt dobbers have made a home in the tube, next one thing that will cause a unit to freeze up is low freon, have it checked for proper fill, do not over fill, very hard on compressor.

 

Low freon is probably your problem. Another possibly is if you are in a high humidity region of the country, IE South Texas as of late, make sure you run the A/C on Max Cool. This setting recirculates air from the cab and does not allow any moist outside air to pass through the evaporator possibly causing freeze ups.

 

Low freon. The fix is hook a disposable can of freon to the low pressure side, start truck turn on ac high and let it suck it in. When frost or ice starts to form on the big silver AC Can and line near the firewall you have enough freon in the system. Sounds like you won't need much, 1 can will most likely do it. Available at any auto parts store. Good luck

 

It won't ever freeze or frost a line, especially in Texas. The lines will sweat when it's about right on the charge.