A timed or demand-initiated period that melts frost from an evaporator coil.
Coils running below freezing collect frost, which blocks airflow. Refrigeration evaporators defrost by off-cycle time, electric heaters or hot gas, ended by a termination thermostat or timer. Heat pumps defrost the outdoor coil by reversing to cooling for a short time. A coil that ices up gradually over days usually points to a defrost, fan or door problem before a refrigerant problem.
Exam work areas
F · Maintenance, service and troubleshooting