Tech found system low on R22 and customer stated coil was frozen this morning. Tech verified blower is moving proper airflow. High superheat and low subcooling with a piston. Tech informed customer that the frozen coil was blocking airflow earlier. Tech performed a leak search and found a leak in the evaporator coil. System is 28 years old and recommends replacing, but system can be recharged to get back running. Tech also informed customer about leak freeze and repair options. Customer approved recharge only. Tech recharged per superheat with a fixed orifice, system is now cooling properly. Tech also replaced a damaged 20x20 ceiling tile with an extra the customer had.