During the winter the fan occasionally shuts off on my heat pump outside unit, then restarts. Why?

During the winter the fan occasionally shuts off on my heat pump outside unit, then restarts. Why?

Nothing is wrong with your unit. What appears to be smoke is steam from the outdoor coil after it completes a defrost cycle. After extended run times the outdoor unit will start to build frost or ice on the coil. The system is designed to go in a defrost mode when needed to clear the ice away and keep the efficiency level up.