Why does it stink LOL when you turn on the AC after a long period of inactivity? Any way to get rid of this "stale" odor?

 

A/C 's pull heat and moisture from the air in order to cool it. The moisture is drained from the cab through a hose going from the evap. box through the firewall and onto the ground ( that is why there is a puddle under the truck when the A/C has been on. The drain is not always effective and some moisture sits in the box under the dash. It starts to grow mold and sludge and when you fire up the A/C agian the air blows over this gunk and picks up the odor. you can try cleaning out the evap. box by back flushing it with a cleaner through the drain hose. there are also products available for adding to the box to remove the gunk.