Walk-in cooler/freezer — not-cooling diagnosis

Door/seal — long-open door or damaged gasket lets warm air in, raising temp and frosting the evaporator. Inspect seals for cracks/gaps

Check: Coils — dirty condenser reduces heat rejection (overloads compressor); iced evaporator blocks airflow. Check both coils are clean

What to do: Defrost system — if frost won’t clear, check defrost timer, heater, thermostat. A blocked drain causes standing water and re-icing. Replace the thermostat if it doesn’t respond