OEM Lennox Defrost Control Board — 84W88

The genuine OEM Lennox 84W88 defrost control board is the electronic brain that governs the defrost cycle on your Lennox heat pump, coordinating the reversing valve, outdoor fan, and timing logic based on coil temperature to keep the outdoor unit free of ice. As a direct factory replacement, it delivers the precise control sequence and relay ratings your system depends on for efficient heating.

Common symptoms of a failed defrost control board include the outdoor unit icing over, a heat pump that never enters or never exits defrost, no power to the outdoor fan or compressor contactor, erratic cycling, or blank and unresponsive diagnostic LEDs on the board. Because the board coordinates several components, a fault here often mimics multiple unrelated failures.

Installing the OEM Lennox 84W88 is important because the board's firmware, relay layout, and terminal assignments are matched to your specific heat pump. Generic or salvaged boards may mistime defrost cycles, misfire relays, or fail to communicate with other controls. This factory-original board restores correct defrost logic, dependable operation, and full heating performance.