Which is why every heat pump has a defrost cycle. Also why every heat pump has the resistive heater backup. If you lose power for a long time when it has been

Which is why every heat pump has a defrost cycle. Also why every heat pump has the resistive heater backup. If you lose power for a long time when it has been very cold the system has to be very careful when it starts back up, using the resistive heater to warm the refrigerant and coils to make sure they have not frozen up. But this is all software and is a solved problem.