Heat Craft-Walk in Freezer Tech- found unit off on low pressure and unit was out of refrigerant. I leak tested with nitrogen and found head master line leaking. I repaired leak and tried to re charge unit but head pressure was too high. I power washed condenser coil and re charged unit. I found 4th evaporator motor from left locked up. I replaced motor and re checked operation. defrost timer and heater are working. Box came down to 10 deg