Why Did My Defrost Board and Sensors Burn Out?

A defrost board or sensor issue is usually due to a failure of the electronics that make up the circuit board or the inaccuracy of the temperature sensors. Your heat pump works hard to keep your house warm, and its defrost system can lead to extra wear and tear on your unit if it’s not working properly. This pressure on your system can cause your defrost board to fail. The defrost controls are subject to extreme outdoor temperature swings, humidity and voltage variations. Over time performance and reliability can be diminished.

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Hot Take

During normal heating operation, with the outdoor temperature below 40 degrees, your heat pump outdoor coil will develop a layer of frost or ice. Your defrost board is there to help your unit stay freeze-free with periodic defrost cycles. But if your defrost board is malfunctioning, your heat pump is unable to absorb heat from the outside air.

As your system ages, it loses efficiency. Different parts of your system slow down and can stress out your defrost board, forcing it to bear the brunt of the load. Over time, your defrost board and sensors wear down, can’t keep up, and eventually burn out.

Let’s Pump it Up

Your defrost board and sensors are feeling worn out, so it's time to put a spark back in your system with some help from your local HVAC contractor. A professional technician can diagnose and replace your defrost control board and sensors. These modifications will help to restore your heating system’s performance, saving you money.

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