2nd Gen Non-Engine/Transmission heat/ac control not working

[fred dog]

hello, i have a 95 dodge with cummins and nv4500. problem im having is the heater control does not redirect air to dash vent etc. it just blows on the windshield. ac works fine as it does blow cold air. the problem is the vent control won't allow air to be redirected to other vents. how do i go about fixing this problem. any information will be greatly appreciated, thank you.

 

[fest3er]

hello, i have a 95 dodge with cummins and nv4500. problem im having is the heater control does not redirect air to dash vent etc. it just blows on the windshield. ac works fine as it does blow cold air. the problem is the vent control won't allow air to be redirected to other vents. how do i go about fixing this problem. any information will be greatly appreciated, thank you.

Reattach the vacuum line to the pump below the injection pump. You're missing vacuum between the pump and the knob on the dash.



I was messing with mine one day and pushed the line in too far at the pump. Suddenly had only defrost, which didn't help my nephew at all when I picked him up. He'd been riding his bike and got caught in a cold, drenching rain storm and I couldn't get any heat directed to him to warm him up. Of course, as soon as I dropped him at home, I reached in and pulled the connector apart slightly; it instantly started working.

 

[fred dog]

Iwas working on the fuel solenoid and adjusting the engine rpm but have'nt done anythiing to the vaccume lines. They all look fine, the cruse and power brakes still operate as they should. The problem did start off slowly. It would"nt work and after i got on the highway it did work. Now it does'nt.

 

[firefighter_2000]

Check the lines

Check the lines closely for dry rot or holes. You may have a hole that you cant see. I had the same problem. Cruise and everything else worked fine. Ended up being a dry rotten vac hose on the passenger side near the top of the firewall. I ended up buying a roll of the line and replacing all of it.

Craig

 

[LandShark]

First check to see if the control knob is stripped.

 

[RustyJC]

Defrost is the "fail safe" position should there be a loss of vacuum to the AC/heater/defrost controls. If the control is working mechanically, then it isn't getting a vacuum supply.



Rusty

 

[fred dog]

the knob is not stripped so i will be checking vaccume lines.

 

[SSolderitch]

recir door - to check for operation, pop down the glove box door and watch while turning knob.

temp change - electric motor and plastic drive pin - to check put hand over vent - do you get a temp change with knob change?

defrost and panel, panel only, panel & floor and defrost & floor require the other two doors - to check check for movment with mirror & flashlight. One is on the drivers side and the other is on the bottom (just above the hump). The bottom one turns on & off the floor ducts. it has two vacuum lines, red & brown, both have vacuum for full floor ON. No vacuum is full floor OFF. One line with vacuum is for patrial floor. The actuator on the drivers side dirrects between panel and/or defrost. To check for a bad switch and lines use a hand pump directly on each actuator ports (and on both ports of the floor actuator). You may find a bad switch, actuator or line... But first check the the vacuum at the firewall behind the turbo, you should get 25 on the gauge.

 

[fred dog]

heat/ac not working

im going to have to pick up a vaccume gauge when i go to town so i can check the above. all the lines look ok but it will be difficult to see minor cracks in tubing.

 

[HHhuntitall]

Well, usually you don't have to have a guage, in my opinion. Pull the line, if you can feel a good vacuum on the tip of your finger, put it back together and move down the line. The most common problem I see is an unplugged line under the hood. Next, is the actuator on the floor just above and to the left of the accelerator pedal. I'd suggest starting it, Checking vacuum at that actuator, turn on the air, and reach up and pull that actuator down and see if it redirects air. If it's getting vacuum, then the actuator is most likely bad. The earlier models, prior to mid '96 didn't have check valves in them, so sometimes they draw engine oil into the lines, which practically dissolves the rubber in the diaphram that makes the actuator move. Sometimes, when you manually pull it down, it'll stay until you stop the engine or change the door setting. I believe the Dodge part number is CH4740279-AB... ... I think. Dealer price is @ $66.