I had a problem on the way to work this morning, I turned my heater on and i realized that the hot air was coming out of the defrost vents no matter what setting i had it on. I would put it to blow out on the floor out the front vents out both and the defrost and it wouldnt change, no matter what setting i had it on it would only blow out of the defrost vents. The low-high works, i didnt try to do it on the AC cuz its like 5 deg here. Any thoughts?

 

Ck your vac. lines for leaks underhood first-if all ok,ck mode door pivot arm-just above the trans tunnel on bottom of hvac case-sometimes the arm falls off

 

ok thanks ill try those

 

Did this fix it?

if so, which was it?

and how hard was the diagnose/fix?

thanks!

 

same problem here, any answers?

 

As the heater plenum "modes" are all vacuum operated, (except hot/cold) if non of them work first look for lack of vacuum usually under hood probably a line off or line worn through.

 

Those systems revert to defrost when vacuum is absent so the only way it can only work on defrost all of a sudden is all vacuum is lost.

 

It would be wise to check all of the vacuum lines/connections. But the most common failure point is under the driver-side battery tray. The servo for the cruise is under there. Battery acid drips down on the plastic vacuum line and eats a hole in it. HTH

 

Not sure on the Ram but my F-250 and Dakota both have a resistor for the heater blower. When it goes bad the heater reverts to the defrost position only. Replace the resistor for about $14 and it's back to normal. I think it's mounted on firewall or under the glove box with 2ea screws.

 

I fixed mine last year it cost like $3 from napa for the tubbing to replace the lines, easy to find, just follow the lines, for you digman, there is one under the battery on the drivers side, and then one right under your injection pump.