Tempstar Defrost Control Board for T4H548GKD100 — OEM 1173636 Heat Pump Board | Ships Today
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Overview
This is a genuine OEM defrost control board (part number 1173636) for the Tempstar T4H548GKD100 heat pump. The defrost control board is the brain of the heat pump's defrost cycle — it monitors the outdoor coil temperature and accumulated run time, then triggers a defrost cycle to melt frost and ice off the outdoor coil during heating operation. It coordinates the reversing valve, outdoor fan, and auxiliary heat to keep the system running efficiently in cold weather. When this board fails, the unit may ice over completely, fail to switch into or out of defrost, short-cycle, or stop heating altogether. The board operates on a 24V control circuit and includes timing logic for the standard defrost intervals used on Tempstar heat pump platforms.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar |
| Control Voltage | 24V |
| Application | Heat Pump Outdoor Unit |
| Fitment | OEM Direct Replacement |
Compatibility
This board is a direct OEM fit for the Tempstar T4H548GKD100 heat pump. It is also used across related ICP-family outdoor units (Heil, Comfortmaker, and other Tempstar models) that share the same defrost control platform. Always confirm the part number on your existing board matches 1173636 before installing.
Installation Guide
- Safety First — Disconnect power at the disconnect and breaker, and verify zero voltage with a multimeter before touching any wiring.
- Access — Remove the outdoor unit's electrical access panel.
- Document — Photograph every wire and connector on the existing board before disconnecting anything.
- Remove — Label and unplug the wire harnesses, then remove the mounting screws and lift out the old defrost board.
- Install — Mount the new 1173636 board, reconnect each harness exactly per your photos, and confirm all connectors are fully seated.
- Test — Restore power and verify the unit enters heating, and force a defrost cycle to confirm the board commands the reversing valve and fan correctly.
Signs You Need a Replacement
- Outdoor coil ices over and never goes into defrost
- Unit gets stuck in defrost and won't return to heating
- No 24V output to the reversing valve or outdoor fan
- Visible burn marks, corrosion, or scorched relays on the board
Shipping & Returns
Ships same day on orders placed before 3 PM CST. 30-day returns on unused parts. 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