Lennox 28W59 Control Box Refrigerant this HVAC control transformer ensures this HVAC control transformer ensures a secure electrical connection within tight air handler or furnace vestibules install the valve in a vertical orientation with the solenoid coil facing upward this factory spec metal housing provides the necessary environmental shielding and precise mounting points for internal circuit boards Maintaining the integrity of the Lennox furnace control box is critical for preventing vibration induced wiring failures and ensuring the internal HVAC electrical components operate within their designed thermal parameters