ICP Defrost Control Board for WPH3484000RKC1 — OEM 1178001 | Ships Today

Overview

This OEM control board (factory part number 1178001) is the electronic brain of the ICP/Tempstar/Heil WPH3484000RKC1 packaged heat pump. It manages the defrost cycle, reversing-valve sequencing, compressor timing, and the low-voltage relay logic that coordinates heating and cooling demand. When this board fails, the unit may stop defrosting, short-cycle, run the compressor without the fan, or fail to switch between heating and cooling. Because the board interprets sensor inputs and the 24V thermostat signals, an intermittent or failed board often shows up as erratic, hard-to-trace behavior rather than a clean no-start.

Specifications

Compatibility

Direct OEM fit for the ICP/Tempstar/Heil model WPH3484000RKC1 and shared-chassis units in the same family. Always confirm the part number printed on your existing board matches 1178001 before installing.

Installation Guide

1. Safety First — Disconnect power at the breaker and verify zero voltage with a multimeter before touching any wiring.
2. Access — Remove the control-access service panel on the unit.
3. Document — Photograph every wire and terminal position before disconnecting anything.
4. Remove — Label and unplug the wire harnesses, release the board standoffs/screws, and lift out the old board.
5. Install — Mount the new board on the same standoffs and reconnect each harness exactly per your photos.
6. Test — Restore power, run a heating and cooling call, and confirm proper defrost and reversing-valve operation.

Signs You Need a Replacement

• Heat pump ices over and never runs a defrost cycle.
• Unit short-cycles or fails to switch between heating and cooling.
• Compressor or fan runs at the wrong time, or not at all, on a valid thermostat call.
• Visible scorching, burnt traces, or a blown relay on the board.

Shipping & Returns

Ships same day on orders placed before 3 PM CST. 30-day returns on unused parts. Backed by the National HVAC Parts fitment guarantee.