Fixed the heater controls not vacuum still need help with temp guage and reading schm

[928 Otto]

First thanks for all the help I would be lost without you guy's. The original problem was. I was driving with the heat on low and in an instant it went to high speed and defrost and the temp gauge went to zero and the central warning light went on. The thought was a vacuum problem it wasn't. After taking lot's of things apart I accidentally touched the metal pod holding the solenoid valves to a piece of metal grounding it and all the heater controls worked perfectly. So I attach a wire to it and to ground and it's fixed but the temp gauge still at zero. But it's not the right fix that has to be where ever the solenoids ground through the heater control.

So here's where I need help with the schematic. I have the gray shop manuals. Model 83 part VIII or page 97-171 shows the heater control assembly and the solenoid valves and the wire at the left end of the page X/12 is for the temp gauge. They all go to a control unit what and where is that control unit? Also where is the ground for the heater control and the solenoid's is it in that control unit? Also missing from this page are the wires for the three plugs for the heater control? Is there another page in the manual this continues on that shows a breakdown of the control unit and how this all grounds? My best guess is both my problems are in the control unit at the bottom of the page.

Thanks again for all you're help Otto