Hi Mrs. Smith, my name is Trong Son Huynh from HVAC Technical Academy. Today, I’d like to talk about the defrost board.

The defrost board is located in the outdoor unit. Its main function is to monitor the temperature of the outdoor coil.

When the temperature sensor on the coil detects that the coil has frozen and ice has formed, the defrost board will switch the reversing valve to cooling mode. This allows hot refrigerant to flow through the outdoor coil to melt the ice.

At the same time, the system temporarily shuts off the outdoor fan so the condenser coil can heat up more quickly. The defrost board also sends a signal to activate the heat strip in the indoor unit to maintain indoor comfort during the defrost cycle.

This cycle continues until the temperature sensor detects that the ice has melted. Once the coil is clear, the system switches back to normal heating mode.

When the defrost board goes bad, the heat pump system may fail to remove ice from the outdoor coil. This can lead to poor heating performance and excessive ice buildup.

Some common causes of defrost board failure include extreme temperature fluctuations and dust buildup. Dust and debris can affect the board and potentially cause electrical issues within the circuit.

That’s an overview of the defrost board and how it operates.

Speaker: Roger Williford

Hello everybody. It’s your boy Roger. I’m gonna be telling you about a defrost board today.

Basically your defrost board, it just tell you signals about your fan, it give you your 24 volts, it send signal to your heat strip.

And then what can happen on your defrost board? Any little thing can happen like if an amp get into it to just stop working right and not function right.

So, and you can replace them. So, that’s what I’m—that’s all I know about a defrost board.