Tempstar Defrost Control Board for T4H324GKD300 — OEM 1173636 | Ships Today
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Overview
The OEM defrost control board (part number 1173636) is the logic center that manages the defrost cycle on your Tempstar T4H324GKD300 heat pump. During heating mode, frost and ice accumulate on the outdoor coil; this board monitors elapsed run time and coil temperature, then commands a timed defrost cycle—reversing the refrigerant flow and energizing the auxiliary heat—to melt that ice and restore efficiency. When the board fails, the system can no longer initiate or terminate defrost correctly, which leads to a coil that ices over solid, sharply reduced heating output, a unit that runs constantly, or one that never defrosts at all. A failed board is one of the most common causes of a heat pump that "won't heat" in cold weather.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar (ICP / Heil) |
| Function | Defrost cycle timing & control |
| Fitment | OEM Replacement |
Compatibility
This control board is the factory-specified replacement for the Tempstar T4H324GKD300 heat pump. Because ICP, Heil, Comfortmaker, and Tempstar share platforms, it also serves as the OEM board on closely related models in the same family. Always confirm your existing board's part number before ordering.
Installation Guide
- Safety First — Disconnect power at the disconnect and breaker, then verify zero voltage with a multimeter before touching any wiring.
- Access — Remove the outdoor unit's control-panel service cover.
- Document — Photograph every wire and terminal connection on the existing board before disconnecting anything.
- Remove — Label and disconnect the low-voltage and line-voltage leads, release the mounting standoffs, and lift out the old board.
- Install — Seat the new board on the standoffs and reconnect each wire exactly as photographed.
- Test — Restore power and verify the unit initiates and terminates a defrost cycle normally.
Signs You Need a Replacement
- Outdoor coil ices over and the unit never defrosts
- Heat pump runs continuously but delivers little or no heat
- Defrost cycle runs too often or won't terminate
- Auxiliary/emergency heat never engages during defrost
Shipping & Returns
Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days