Arrived on site and checked in with customer. Located walk in unit equipment. Visually inspected equipment. Coils dirty, all components functioning, site glass flashing and no signs of leaks or damage. Checked start and run capacitors. Compressor cap 0/30. Fan cap 4.4/5. Compressor start cap within specifications. Replaced run capacitor on compressor and CFM. Contactor in good condition. Cleaned coils (both condenser and evaporator). Checked / cleared drain. Hooked up gauges and monitored system vitals. Had hoped site glass would clear up after removing air flow obstruction of dust and lint, but unit is low on charge. Unit runs 507A and we don’t carry it. Will quote out leak search and refrigerant.