How many of us are there? Owners of Dodge based RV's?

New member here! Just joined the rv.net site. We recently bought a 1976 Dodge Avion 22 foot rv. MB400 chassis 440 engine. It is in really good shape except that a previous owner painted it with a brush.




Now that it is getting colder I tried to slide the temperature selector to heat but nothing happened. The wire was disconnected from the valve in the heater hose. The valve does work the cable doesn't move. How do I get to the back of the heater control part of the dash?