I purchased a property with the Sears Kenmore 600 Series Model 867.733531 wall mounted natural gas heating unit that isn't working right. The burner starts when I switch it to automatic, but the fan won't start and the heat doesn't shut off on high heat. The fan only comes on in manual mode. I believe the problem is in the Thermo Discs, It has three Thermo Discs, 2 are the two wire type, the third is a three wire type. I would like to get a wiring diagram or at least a clue as to the operating functions of the three discs and the rotary control switch. I'm thinking I may have two bad switches, one to start the fan and the other to turn off the burner on high heat.