What usually causes the most common refrigeration and air conditioning faults, what you can safely check yourself, and when to call an engineer.
The most common causes are a blocked or dirty condenser, a failed condenser or evaporator fan, a refrigerant leak, a faulty thermostat or controller, or worn door seals. Check the condenser is clear and the doors close properly; if it still runs warm, call an engineer before stock is lost.
Cold rooms usually lose temperature because of evaporator icing, a failed defrost, a refrigerant leak, a condensing unit fault or a damaged door seal or strip curtain. A rising temperature with the unit running constantly points to low refrigerant or a blocked coil.
Ice build-up usually comes from a failed defrost heater, timer or sensor, a door that is not sealing, or a blocked drain. Repeated icing restricts airflow and the freezer warms up.
Compressors overheat when the condenser is blocked, refrigerant is low, the ambient temperature is too high or there is an electrical fault such as a failing start capacitor or contactor. Repeated tripping needs a diagnostic visit before the compressor fails completely.
Check the power, the remote or controller mode and the filters first. Beyond that, the usual causes are low refrigerant, a failed fan or compressor, a blocked condensate drain, a sensor fault or a communication error between the indoor and outdoor units.
Water leaks are almost always a blocked condensate drain, a failed condensate pump or a cracked drip tray. Switch the unit off to avoid ceiling damage and have the drain cleared.
Refrigerant does not get used up; if the charge is low there is a leak. The leak should be found and repaired first, then the system pressure-tested and recharged to the correct weight.
