Vannin' Home Forums Dodge Troubleshooting (Dodge) Need help re: heat/ac

Hi, I just bought another '77 Dodge which has factory a/c. Problem I'm having is push button controls for "off" "min a/c" "max a/c" "heat" "def" do not work properly. Push any control other than off, heat comes out def and heat the same. I think the problem is in the vacuum controled push buttons but cannot find vacuum diagram for controls. System is not currently hooked up. Anyone out there have knowledge of where I could find diagram? Tried local Chrysler dealer already. Haynes manual I have for that year does not have diagram. Any help would be greatly appreciated. Cheers!

I had an '85 Dodge with factory air and push button controls. It is very possible problem is in the control panel itself. I had to replace mine when the buttons all of a sudden jammed. I know you say you can still push the buttons and it seems it is stuck in bi-level mode. Do the buttons feel any different? Lose? anything rattling? It is not a difficult or expensive item to repair. I believe it is a common problem since I went to a junk yard first to get a replacement and all dodge vans switches were missing. Don't have my manual handy but just a thought.
GupEBoy

I just looked through my original manual and it doesn't say a thing. I will take a look under my hood to see if there's a diagram. The only problem would be to remove the hood and scan it. I'll get back.

Well I don't have to remove my hood. The only diagram was the emission control B.S. Sorry I wasn't more help. I would listen 4 vacuum leaks, check lines for cracks, ect. S.P.

Greetings MTM41;

You say you have a 77 with factory air. The controls you are explaining sound like from a 78 and up van. My '77 had factory air and it looked like an aftermarket unit that was installed at the dealer. I don't believe before 78 they actually had in dash air. At least I never saw one. If this is the case and someone added the air to your van maybe the vacuum lines are mixed up or not all on.

My '77 manual shows 2 different heater controls w/air. One for the compact dash and one for a regular dash.

Are you sure the buttons are vacuum because in my chiltons i have the control unit schematics but shows no vacuume lines just electrical. there should be 4 electrical connectors on the back. 2 three prong and two single prong. there does appear to be three other prong on the left of the unit, I cant tell from the drawing but they could be the vacuume connections. If you need info on the wiring i can help but i have no info on vacuum lines.
p.s. it sounds more like a problem with the vent control cable

Any time a manual is not available, borrow a smoke generator, Sometimes Canadian Tire may lend you one, unhook any vacumn line form the engine, plug the end and run smoke through the system. The smoke will show any leaks. Since you are also having trouble with the tranny, I suspect a vacumn leak on the manifold, or the kick down system.
If you have a stethoscope, take off the medical end and insert a 12 inch section of new steel brake line. With the engine running, search around the manifold and a/c controls for leaks. You will hear them ..
Trust me, I am a Doctor.

Is the van idling rough? That to might indicate a vacuum leak. I used a propane torch *unlit* around my carb ect. and when the propane replaced the air that was being sucked in the rough idle dissapeared. I then knew the leak was in the area the propane was in. This will not help if it is a vacuum line. That smoke idea sounds like a winner though.