The book says there must be 11 or more volts to the switchover valves, which I get on the red/blac wire to ground. The brown/blue wire goes from the CCU through the temp reostat (wheel) to the temp control box back to the CCU. I'm at a loss as which is bad. Common sense tells me it's the CCU. But I switched that at first, with the same results. It's possible that I got a bad 2nd CCU also. But funny how it gave the same problems. I've had CCU problems before but mostly with servo's not open/close right.
I'm afraid that if I buy another CCU and hook it up that whatever is the problem it will discombooberate the new one also. Can a bad Temp Control Unit cause CCU damage?