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HVAC Defrost Troubleshooting | Timers, Sensors and Boards

By Elijah Behncke

March 25, 2026

Is your HVAC system not going into defrost mode? In this video, we break down defrost troubleshooting step by step — covering timers, sensors, and boards so you can diagnose the problem fast.

Learn how defrost timers work (30, 60, and 90-minute runtime cycles), how to test and jump defrost sensors, how to speed up the timer for quick testing, and how to identify failing relays that mimic fan motor issues. We also cover how to trace shorts past the defrost board all the way to the contactor — because the board isn’t always the culprit!

#Defrost #defrost board #heat pump #heat pump defrost #heating #hvac

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