Tempstar Defrost Control Board for T4H524GKD100 — Heat Pump Board | Ships Today

Overview

This is a genuine OEM defrost control board (part 1173636) for the Tempstar T4H524GKD100 heat pump. The defrost board manages the heat pump's defrost cycle — it monitors the defrost thermostat and timer, energizes the reversing valve, shuts off the outdoor fan, and brings on auxiliary heat to clear frost from the outdoor coil during winter operation. When the board fails, the system can't defrost properly, leading to ice buildup on the outdoor coil, poor heating performance, frozen units, or a heat pump that won't run at all. Symptoms include a thick layer of ice on the condenser, the outdoor fan behaving erratically, no changeover during defrost, or completely dead controls.

Specifications

Compatibility

Built for the Tempstar T4H524GKD100 and matching ICP / Heil / Comfortmaker heat pumps that use this defrost board. Confirm the OEM part number on your existing board before ordering, as board revisions vary by platform.

Installation Guide

1. Safety First — Disconnect power at the disconnect and breaker, verify zero voltage with a multimeter.
2. Access — Remove the control compartment service panel.
3. Document — Photograph every wire and connector position on the existing board.
4. Remove — Disconnect all plugs and leads, then unclip or unscrew the old board from its standoffs.
5. Install — Mount the new board and reconnect every connector to the matching terminal per your photo; set any defrost-time jumpers to match the original.
6. Test — Restore power, run a heating call, and verify normal operation and (where possible) a forced defrost cycle.

Signs You Need a Replacement

• Outdoor coil ices over and won't defrost
• Outdoor fan runs erratically or not at all
• No reversing-valve changeover during defrost
• Dead controls / no response on a heating call

Shipping & Returns

Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.