HI,
I just wanted to share my experience with you all and at the same time thank everyone for their input
THe vehicle is a 1983 TD wagon (123)
Poor heat control and discovered a ripped diaphram on the monovalve. Replaced and then I had great heat. Boy did I have HEAT!!!!
Could not regulate temp at all. The monovalve was never getting a Ground signal to close so It allowed full flow. I removed the pushbutton control unit and thanks to many members previous post I learned that when the unit is off, "O" pushed the monovalve should be energized. It wasn't.
I decided to go to my local friendly junkyard where I got my engine from and did some shopping. I pulled a pushbutton unit from a 85 CD and a Temp control box (silcver box behind glovebox) figuring it must be one or the other.
Well when I installed the pushbutton unit, that solved the problem. Everything works perfectly now. The temp wheel controls the inside temp perfectly.
I will add that before I installed the "new" CCU unit I took apart and cleaned the thumbwheel contacts. They were filthy. I have also replaced the foam tube that connects the dash temp sensor. Mine was as expected corroded and even broke in half.
I also notice now at nite that what ever button I have pushed in on the CCU, It lights up brighter to let you know what mode you are in. My old one never did.
I just wanted to share my results with everone and hopefully if someone else experiences the same thing, It will save them alot of diagnostic time.
THanks again to all contributors,
Mike Moran