I was told by my local indy who has worked on these things since they were new that the entire monovalve needs to be changed if disconnected and no heat at speed. The unplugged monovalve defaults to full heat period. He said it was a yes/no question and not to over think it.

He also showed me a 12v test light that he used to use for testing the temp control. It was basically 2 wires and a bulb cut from a harness. He said that the light would come on if the temp wheel was turned to high heat. If not, something is wrong with the dial.

He also said to change the auxillary pump if the push button needed changing. The pump can take out the push button CCU.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.