Lennox Surelight Control Board Wiring Diagram. Ignition control board, a wire must be connected from the heat pump y1 terminal on the fm21 board to the y terminal on the furnace surelight ignition control board. · 83m00 has been discontinued.

It's a lennox, with a control board model # 63k8901). We traced that back up to the splice with the compressor signal and the thermostat wires and found that again, the yellow wire was *not* connected there. Lennox 58l61 ignition control board kit.