Tempstar Defrost Control Board for TXH537GKA100 — Heat Pump Defrost | Ships Today
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Overview
This is the genuine OEM Tempstar defrost control board, part number 1173636, for the TXH537GKA100 heat pump condensing unit. The defrost control board is the brain of the outdoor unit's heating cycle — it monitors coil temperature and run time, then commands a defrost cycle to clear ice from the outdoor coil so the system keeps delivering heat. It energizes the reversing valve, sequences the compressor and outdoor fan, and coordinates with the indoor blower during defrost. When this board fails, the unit can frost over and lose heating capacity, run defrost continuously, or fail to switch between heating and cooling. Operating on a 24V control signal, it is the correct factory replacement for this model.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1173636 |
| Type | Defrost Control Board |
| Brand | Tempstar (ICP / Heil family) |
| Control Voltage | 24V |
| Application | Heat Pump Outdoor Unit |
| Fit | OEM Direct Replacement |
Compatibility
Engineered as the factory-correct defrost board for the Tempstar TXH537GKA100 heat pump. Because Tempstar, Heil, Comfortmaker, and other ICP-family brands share components, this board also services equivalent ICP-built units that originally specified part 1173636. Always confirm the printed part number on your existing board before ordering.
Installation Guide
- Safety First — Disconnect power at the outdoor disconnect and breaker; verify zero voltage with a multimeter before touching any wiring.
- Access — Remove the control-panel access cover on the condensing unit.
- Document — Photograph every wire and terminal connection on the existing board before disconnecting anything.
- Remove — Label and unplug the wire harnesses, then unscrew the failed board from its standoffs.
- Install — Mount the new board on the standoffs and reconnect each harness exactly per your photos and labels.
- Test — Restore power, initiate a defrost (or force one) and confirm the reversing valve, compressor, and fan sequence correctly.
Signs You Need a Replacement
- Outdoor coil ices over and heating output drops.
- Unit gets stuck in continuous defrost or never defrosts.
- No switching between heat and cool modes (reversing valve not energizing).
- Visible burn marks, corrosion, or failed relays on the existing 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