Walk-In Cooler Unit was at temperature when I arrived, Checked thermostat and evaporator and were good, Checked condenser unit and found some bubbles in site glass, Checked refrigerant level on receiver and found to be slightly low and also found king valve seat to be leaking on receiver, I tightened seat on king valve and added 11 ounces of R22 to system, unit is down to set temperature at this time and cycling properly