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This is the OEM defrost control board (part number 1173636) for the Tempstar T4H448GKA100 heat pump. The defrost control board governs the heat pump's defrost cycle — it reads outdoor coil temperature and accumulated run time, then commands the reversing valve, auxiliary heat, and outdoor fan to melt frost off the coil in cold weather. A failed board can't defrost correctly, which causes ice buildup on the outdoor coil, weak heating output, short cycling, or a complete heat-pump lockout. Installing the genuine OEM board restores proper defrost timing and protects the compressor from liquid slugging.
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar |
| Fits Model | T4H448GKA100 |
| Control Voltage | 24V |
| Application | Heat Pump Defrost Control |
Factory replacement for the Tempstar T4H448GKA100 heat pump. The same 1173636 board is used across many ICP-family (Tempstar / Heil / Comfortmaker) heat pumps in this series — verify your existing board's part number before installing.
Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.