When it’s cold outside and your air conditioner is set to heating mode, the outdoor unit can become very cold. This may cause frost or ice to form on the outdoor coil.

To prevent this from becoming an issue, the system automatically activates a defrost cycle. During this process, the unit briefly changes how it operates to melt the ice — it may sound like it’s turning off or switching modes. Once the ice has cleared, the system returns to normal heating.

This is completely normal and can take anywhere from 20 to 40 minutes, depending on the size and type of the unit. The defrost cycle helps protect the system and ensures it continues to operate efficiently.