Arrived at location on 12/28/22 - On site for walk-in cooler not at temperature, proceeded to check unit noticed unit at temperature at 37f ,went up on roof to checked my refrigeration lines that good. Checked defrost timer put unit on defrost waited for it to come off defrost never did , so I removed defrost timer. Installed new defrost timer .turn unit on put unit on defrost unit went on defrost & came back on , unit fully operating, unit temperature on departure & 37f part number for Defrost control from truck in office notes