ICP Defrost Control Board for WPH4424000RKA1 — 24V Heat Pump | Ships Today

Overview

This OEM control board (Part No. 1178001) is the brain of your ICP / Tempstar / Heil WPH4424000RKA1 heat pump. It manages the defrost cycle, sequences the compressor and condenser fan, switches the reversing valve for heat/cool changeover, and protects the system with timed anti-short-cycle logic. Built on 24V control inputs, the board reads the defrost thermostat and reversing-valve signal to keep the outdoor coil clear of frost in heating mode. A failed board commonly causes no-heat, no-defrost, ice-up on the outdoor coil, or a unit that won't switch between heating and cooling.

Specifications

Compatibility

Designed for the ICP/Tempstar/Heil WPH4424000RKA1 packaged heat pump and used across matching ICP-family WPH-series control assemblies. Match the board's connector layout and pin count to your existing board before installing.

Installation Guide

1. Safety First — Disconnect power and verify zero voltage with a multimeter.
2. Access — Remove the control-box service panel.
3. Document — Photograph every plug, terminal, and the defrost-timer jumper position before disconnecting.
4. Remove — Unplug the harnesses and unclip/unscrew the old board from its standoffs.
5. Install — Mount the new board, reconnect each harness per your photo, and set the defrost timer jumper to match.
6. Test — Restore power and confirm normal startup, changeover, and a forced defrost cycle if accessible.

Signs You Need a Replacement

• Outdoor coil ices over with no defrost cycle in heating.
• Unit won't switch between heating and cooling modes.
• Compressor or fan won't sequence on, or short-cycles.
• Visible burnt traces, scorched relays, or a cracked board.

Shipping & Returns

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