Tempstar Defrost Control Board for T4H448GKD200 — Heat Pump | Ships Today

Overview

This genuine OEM defrost control board is the brain of the defrost cycle on the Tempstar T4H448GKD200 heat pump. It monitors coil temperature and run time, then commands the reversing valve, condenser fan, and auxiliary heat to clear frost from the outdoor coil during winter operation. A failed defrost board is a leading cause of a heat pump that ices over, blows cold air in heat mode, or short-cycles. Symptoms include a thick layer of ice on the outdoor coil that never clears, a unit stuck in defrost, no reversing-valve switching, and the condenser fan running at the wrong time. Because this board coordinates several components, a fault here can mimic compressor or sensor failures.

Specifications

Compatibility

Direct OEM fit for the Tempstar T4H448GKD200 heat pump and shared across matching ICP-family outdoor units including Heil and Comfortmaker heat pumps. Always confirm your model and serial label before ordering.

Installation Guide

1. Safety First — Disconnect power at the breaker and verify zero voltage with a multimeter before servicing.
2. Access — Remove the condensing unit service panel to reach the control board.
3. Document — Photograph every connector, terminal, and the defrost sensor lead before disconnecting.
4. Remove — Unplug the wiring harnesses and unscrew the old board from its standoffs.
5. Install — Mount the new board and reconnect each harness and sensor lead exactly per your photo.
6. Test — Restore power, confirm normal heat-pump operation, and verify the board can command a defrost cycle.

Signs You Need a Replacement

• Outdoor coil ices over and never completes a defrost cycle.
• Heat pump blows cold air or fails to switch into defrost.
• Reversing valve or condenser fan operate at the wrong times.
• Unit short-cycles or shows no response at the board terminals.

Shipping & Returns

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