ICP Defrost Control Board for WPH4604000RKA1 — 24V Circuit Board | Ships Today

Overview

This OEM circuit control board (part number 1178001) is the defrost control board for the ICP/Tempstar/Heil WPH4604000RKA1 heat pump. The board manages defrost timing and termination, energizes the reversing valve and contactor, and coordinates the condenser fan during defrost cycles using its 24V control inputs. When the board fails, the heat pump can ice over in winter, skip or get stuck in defrost, fail to switch between heating and cooling, or stop responding to the thermostat entirely. A direct OEM replacement restores correct defrost logic and protects the outdoor coil and compressor.

Specifications

Compatibility

Engineered for the ICP/Tempstar/Heil WPH4604000RKA1 heat pump. Match the OEM part number and board layout to your existing control board before installing.

Installation Guide

1. Safety First — Disconnect power at the disconnect and breaker, then verify zero voltage with a multimeter.
2. Access — Remove the condenser control panel cover.
3. Document — Photograph every wire and terminal position on the board before disconnecting anything.
4. Remove — Label and unplug the connectors, then unscrew the old board from its standoffs.
5. Install — Mount the new board and reconnect each wire to the matching terminal per your photos.
6. Test — Restore power and verify normal operation, defrost initiation, and mode switching.

Signs You Need a Replacement

• Outdoor coil ices over and never defrosts in winter
• Heat pump stuck in defrost or won't switch modes
• Unit unresponsive to thermostat calls
• Visible burn marks, scorching, or failed relays on the board

Shipping & Returns

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