1988 FC water coach heater question

[birdshill123]

We are on our maiden voyage in the new to us Bird. I will post a story
of the trip later. Right now I have a small problem. I have the blue
Box for our unit but section 10 with all the plumbing and electrical
diagrams is missing. Our coach has a heater (engine hot water) under
the kitchen drawers beside the fridge. We are in AZ. It was 101 today.
My wife went to get something from the drawers and she said she almost
burned herself. I checked and the heater core. It is damn hot. Checked
the switch for summer/winter and it is set on summer. How do I stop
the water from circulating to the heaters? I know the switch is
supposed to activate a solenoid. Where is that solenoid located? Why
couldnt they use a simple Ranco valve? Without the diagram for the
heaters I am having trouble figuring how this works. Are there
seperate lines going to the water heater? For now I would like to just
install a simple gate valve to stop the water from entering the
heater. I havent yet checked to see if the other heaters are also hot.

Thanks: Bruce