2nd Gen Non-Engine/Transmission 95 2500 diesel hvac interior cab air flow control question

[Larry Ward]

Have tolerated directional air flow control of heat or ac that has a mind of its own. In other words the rotary selection of air flow will at times be directly at you another time it may be up on windscreen, etc. AC and Heat controls and fan speeds work fine. So I presume if vacuum is ok at the rotary control, it would then be some downline failure either mechanical or vacuum at a flap solenoid. Vacuum must be working generally as brakes work fine, etc. I could not seem to phrase my "search" inquiry to nail it so must post this "new" (?) thread.



I will add that we have the dash partly removed but hesitate to do more. Cannot figure out what next to remove and not sure if the whole top of dash has to come out. My Haynes manual does not show enough to get at the hvac air control box and its guts. Have a complete printout of the box and all its parts. I see there are 3 solenoid actuators and expect trouble may be there. But getting there is my present roadblock.



Thanks for any replys. Larry

 

[Axtell3]

Removing Dashboard - Replacing Evaporator 1995 2500 - Dodge Cummins Diesel Forum



Here's the one I found when working on mine.

 

[Bob4x4]

Should not have to remove the dash !

The actuator that works the defrost is right by the drivers rt foot

 

[mwilson]

Larry,

You should really get your hands on a hand vacuum pump and observe what is going on before throwing parts at it that may not be needed.



You may have a leak that is not at the actuators for example.



A huge leak results in defrost only, that is the design of the system.



A failure of the vertical actuator to the right of the throttle pedal results in no flow to the dash vents. Been there, fixed that one.



Do a search, there is troubleshooting and function information available on this site.



Mike.

 

[mwilson]

Start with this thread,

https://www.turbodieselregister.com...sions/225637-heat-ac-control-not-working.html



If you want more info search using "Heater Vacuum" and select 2nd gen from the menu. That will bring all kinds of info.



Mike.

 

[BigPapa]

I've recently repaired a vacuum leak on my truck that was about to drive me crazy. My vents would sometimes default to the defrost, sometimes work great, sometimes in between, and never blow out the floor vents. Occasionaly my cruise wouldn't work. About the time I'd decide to do something about it, it would be OK for a week.



Finally narrowed it down to the rubber boot at the vacuum pump where vacuum line connects. No visible cracks or holes, but it felt soft and "grainy". I replaced it and all is well.

 

[PToombs]

My '97 truck has air issues also. I looked up under the dash and the actuator above the pedal has no door hooked to it! I looked at a buddies truck and then at mine closer and think the door is gone completely.

Can I get access to that without pulling the whole dash? I see the front of the HVAC ductwork comes off right there and wondered if I could just put in a door.

Sorry for the hijack.

 

[GAmes]

Larry, ditch the Haynes manual. They are only good as emergency toilet paper. Genos Garage has factory service manuals on CD and paper book.



The rubber billows in the vacuum actuators crack and sometimes work intermittantly. The one that usually fails first is the one everyone else has mentioned, right above the go pedal.



Pete, I replaced that actuator a long time ago and IIRC broke the arm that connects to the door. I don't remember all the details, but somehow I managed to drop the door into the HVAC. The only fix is to drop or remove the dash and split the case.

 

[PToombs]

Thanks GA. I don't know if mine fell in or not. I just know it ain't where it's spoda be!