It is normal for ice to build up on the outdoor coil, or heat exchanger, during winter heating. The heat pump defrosts the ice automatically to maintain efficient operation. Steam or fog may rise from the outdoor unit during the defrost cycle. Do not allow snow, grass, clippings, vines, shrubs or other items to accumulate on or around the outdoor unit. Do not stack or store items on or around the unit. Maintain a minimum 12 inch clearance between the outdoor unit and snow banks and other obstructions. It is important to allow air to flow to the unit unrestricted. Make sure that no one steps on the copper tubing between the indoor and outdoor units.
Do not place or hang items on the tubing either. The heat pump may malfunction if kinks or dents in the tubing causes refrigerant to leak or restricts refrigerant flow. Repairing or replacing the copper tubing can be expensive.