Tempstar Defrost Control Board for T4H318GKD200 — Heat Pump OEM | Ships Today
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Overview
This genuine OEM defrost control board (part #1173636) is the brain of the Tempstar T4H318GKD200 heat pump's defrost system. In heating mode the outdoor coil collects frost; the defrost board monitors elapsed run time and coil temperature and periodically reverses the system into a short defrost cycle to melt that frost so the unit can keep heating efficiently. The board coordinates the reversing valve, condenser fan, and compressor timing during defrost, and provides the low-voltage relay logic that ties the thermostat call to the contactor and other outdoor components. A failed defrost board commonly shows up as a heat pump that ices over solid in winter, never defrosts (or defrosts constantly), or stops responding to the thermostat.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar (ICP) |
| Control Voltage | 24 VAC |
| Application | Outdoor Heat Pump |
| Function | Defrost timing & cycle control |
Compatibility
Direct OEM replacement for the Tempstar T4H318GKD200 heat pump. This ICP-family defrost board is shared across comparable Heil, Day & Night, Comfortmaker, and Keeprite outdoor heat pumps of the same series. Match the original board's part number and connector layout before installing.
Installation Guide
- Safety First — Disconnect power at the disconnect and breaker, then verify zero voltage with a multimeter before touching the board.
- Access — Remove the outdoor unit control-panel cover.
- Document — Photograph every plug, terminal, and the defrost-time jumper setting before disconnecting.
- Remove — Unplug the wiring harnesses, release the board standoffs/screws, and lift the old board out.
- Install — Seat the new board, set the defrost timer jumper to match the original, and reconnect every harness per your photo.
- Test — Restore power, initiate a heat call (or forced defrost), and confirm the board sequences the reversing valve, fan, and compressor correctly.
Signs You Need a Replacement
- Outdoor coil ices over and the unit never enters defrost.
- Heat pump defrosts too often or gets stuck in defrost.
- No response from the outdoor unit on a heating call.
- Burn marks, corrosion, or a failed relay on the board.
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