2000 dodge 2500 Air cond. and heater and fan speeds all work but suddenly
no matter what setting I switch to the air only comes out on the floor.
Could someone give me a headstart on chasing down the most common cause for this.
So far all I did was check the fuse panel but did not find a blown fuse.
Thanks in advance for any help.
dave

 

Probably a vaccum related issue. If the truck is 4 wheel see if your 4WD engages properly.

Could be a hose popped off somewhere, other than I dunno.

 

See here:
https://www.dieseltruckresource.com/...eater+selector

 

I was thinking the same. Look for a vacuum leak.

 

Mine was a vacuum issue when I had that problem but it wouldn't change off of defrost. I thought that was the default position so if you lost vacuum it would turn to defrost automaticaly?

Follow the little hard line from the passenger side of the firewall. It goes across the the firewall and then T's. One line goes down to your transfercase (if 4x4).

 

My 94 had the same problem, under my dash I had a vaccum line come off, near the solenoid that switches vent to defrost etc... My solenoid was shot as well so if I wanted defrost I plugged the line with a screw, and if I wanted heat\air I hooked it back up I know I know If I ain't a hillbilly I don't know what is. We call that "Briar Wired" down here

 

Thank you for the quick response. I'll start looking in the morning and hope I get lucky with a hose problem.
recently had AC recharged and maybe mech. might have bumped something that just now came off.
dave

 

just a follow up. it turned out to be a broken plastic pin that the vacuum solenoid arm attached to. (the solenoid that opens and closes the door for floor vent) It also is the hardest one to get to. I managed to drill small hole in plastic ,dropped a 6-32 screw through hole and attached metal arm to screw.
no room for working so it took quite a while,but the alternative was to remove almost everything under the dash it seemed like.
Working for now and thanks again all for getting me going in the right direction.
dave