heater will only put out through defrost vents no matter where i set the dial is this a vaccum issue or what thanks for the reply

 

If I remember right when I had this problem it was a broken vacuum line by the weatherstripping, under the hood.

 

Turboost has it: no vacuum. Check the line from your vacuum pump up to the firewall, that seems the most likely. I lost mine at one point when the vacuum line to my cruise control rotted through.

 

mine touched an exhaust somewhere and melted through . Small Black plastic line.

Very easy to find.

 

On mine it was the vacuum actuators, but the others are right, start by verifying Vacuum at the back of the head.

Does your Cruise and 4WD work?

 

I have the same problem, but only since Cummins replaced my headgasket, once, twice...3 times. Something tells me they forgot to connect a vacuum line.

 

Vacuum leak.

Vac. line under the D/S battery to the cruise module is the usual suspect.

The acidic spray off the battery screws the line over.

 

Need, don't feel bad, seems like every time I work on mine I pull a Vacuum line off somewhere........ Never seems to be the same place, just the same result.

"Oh well, time to find which one I managed to yank off this time......"

 

Ha, yea...but at least your doing it yourself...I had to pay someone to screw it up!!!