I have a Clayton wood/ coal furnacebuilt around 1988. Igot the furnace used and have no wiring diagram. It has 3 connectors on a circuit board. The top connector goes to the draft blower the middle connector powers the circuit board. My problem is the bottom connector. It has 4 wires red, blue, black, white. The blower motor has these same colors (blower motor has 3 speeds). I thought I would just match the colors but this doesn't seem to work. Can anyone help with a wiring diagram?

Thanks