A standard residential heat pump defrost cycle should typically last between five and fifteen minutes under normal operating conditions. When frost or ice accumulation on the outdoor coil triggers the defrost board, the system temporarily reverses its refrigeration cycle to act like an air conditioner, shuts off the outdoor fan, and engages auxiliary electric heating strips indoors to keep your house warm. During this brief window, the heat energy absorbed from indoors melts the frost off the outdoor coil, creating visible steam rising from the unit. Once the outdoor coil temperature sensor reaches a preset safe temperature (usually around 55 to 65 degrees Fahrenheit) or the maximum time limit (often ten to fifteen minutes) expires, the defrost board automatically terminates the cycle and switches the heat pump back to normal heating mode. You can verify normal operation when the outdoor fan restarts and warm air flows indoors.
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