Tempstar Defrost Control Board for TXH518GKA100 — 24V Heat Pump | Ships Today
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Overview
This OEM defrost control board (part #1173636) manages the defrost cycle on your Tempstar TXH518GKA100 heat pump. It monitors outdoor coil temperature and accumulated run time, then starts and stops defrost to clear frost from the outdoor coil during heating. During the cycle the board energizes the reversing valve, switches in auxiliary heat, and times the compressor and outdoor fan. It runs on a 24V control signal and coordinates the contactor, sensors, and reversing valve coil so defrost happens only when conditions require it. A failed defrost board commonly causes a heat pump that ices over, short cycles, or never switches into defrost — producing weak heat, frozen coils, and elevated energy use.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar (ICP / Heil / Comfortmaker) |
| Control Voltage | 24V |
| Application | Heat Pump Defrost Control |
| Fit | OEM Replacement |
Compatibility
Engineered as a direct OEM fit for the Tempstar TXH518GKA100 heat pump and shared ICP-family platforms sold under the Heil, Comfortmaker, and Arcoaire badges using the same chassis. Verify your existing board's part number (1173636) and connector layout against the unit before ordering.
Installation Guide
- Safety First — Disconnect power at the disconnect and breaker, then verify zero voltage at the board with a multimeter.
- Access — Remove the outdoor unit's electrical access panel.
- Document — Photograph every wire and connector position on the old board before disconnecting anything.
- Remove — Unplug the low-voltage harness and sensor leads, release the mounting screws/standoffs, and lift out the old defrost board.
- Install — Mount the new board, then reconnect each harness and sensor exactly per your photos.
- Test — Restore power, run a heating call, and confirm the unit enters and terminates defrost normally.
Signs You Need a Replacement
- Outdoor coil ices over and the unit never enters defrost.
- Heat pump short cycles or won't switch between heating and defrost.
- Reversing valve or auxiliary heat fails to energize on a defrost call.
- Visible burn marks, corrosion, or no diagnostic LED activity 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