York Gas Furnaces: TM9M/YM9M

Re: Add-On Heat Pump Stuck In Cool

When this furnace is used in an add-on heat pump application, the heat pump only runs in the cooling mode ("O" stays energized).

► There is a jumper on the furnace control board to select Heat Pump: "Yes" or "No".

• When Heat Pump mode is set to "No", the control board energizes "O" continuous.