HVACR technician responded to call at a weight loss center in El Cajon, California to perform maintenance on two ICP package units and repair a non-operating freezer. Technician completed maintenance on HVAC units then proceeded to repair the freezer. He found that the evaporator coil was iced up and much of the rest of the unit was full of ice as well. Tech cleaned the ice off the unit and the unit was restored to full operation.