Tempstar Defrost Control Board for T4H442GKD100 — Heat Pump OEM Board | Ships Today

Overview

This OEM defrost control board (part number 1173636) governs the heat-pump defrost cycle in your Tempstar T4H442GKD100. During heating it monitors coil temperature and run time, then switches the reversing valve, brings on auxiliary heat, and stops the outdoor fan to clear frost from the outdoor coil before resuming normal operation. When the board fails, the outdoor coil ices over and heating output falls, the unit may run continuously, the reversing valve may chatter or stick, or the system may lock out. Installing a new board restores correct defrost timing, protects the compressor, and keeps the heat pump running efficiently in cold weather.

Specifications

Compatibility

Built for the Tempstar T4H442GKD100 heat pump and shared across the ICP family — Heil, Comfortmaker, Arcoaire, and Day & Night units that specify defrost board 1173636. Match your existing board's part number and connector layout before installing.

Installation Guide

1. Safety First — Disconnect power at the disconnect and breaker, and verify zero voltage with a multimeter before touching the board.
2. Access — Remove the condenser control-box cover to reach the board.
3. Document — Photograph every wire and connector position before disconnecting.
4. Remove — Unplug the harnesses, release the standoff clips or screws, and lift out the old board.
5. Install — Seat the new 1173636 board on the standoffs and reconnect each harness per your photo, matching pin-out exactly.
6. Test — Restore power, run a heating cycle, and confirm a normal defrost sequence and fault-free operation.

Signs You Need a Replacement

• Outdoor coil freezes over and won't defrost
• Heat pump runs nonstop or short-cycles in heat mode
• Reversing valve fails to switch or buzzes
• No outdoor unit operation or a control lockout

Shipping & Returns

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