This is my second 2500 and both trucks would have a bad smell when the AC is turned on. I live in a dry climate, it's a brand new truck, I keep it clean, what gives.

 

Ah yes, dog breath... try turning it from recerculation to fresh, for a few minutes before you shut it off!! that should do the trick, works for me!! HTH

 

Thanks, this seems to be a common problem. I try and turn my AC off leaving the blower on a few minutes before shutting off the truck. I also cranked my heater in defrost for a few to dry out the system.

 

something to try would be to run the a/c on full and dump a little either enzyme to kill the bacteria that causes the smell or some kind of odor eliminator down the air vents that are under the wiper cowl panel. this usually will help.