O-034·Operation and maintenance / Air-conditioning operation and maintenance
Air-conditioning maintenance and filters
Routine cleaning, fault indicators and statutory inspection boundaries.
Fixed AC needs routine access to its indoor filters and outdoor unit. The required work and interval come from the instructions for the exact system. There is no single service schedule that applies to every domestic mini-split.
User cleaning is separate from work that opens or services the refrigerant circuit.
Indoor-unit filters
Indoor filters collect airborne dust before it reaches the heat exchanger. A blocked filter restricts airflow and can impair heating, cooling and dehumidification.
The product instructions explain how the accessible filters are removed, cleaned or replaced.
Coils and condensate drainage
Dust or contamination on the indoor heat exchanger can restrict airflow. Cooling also produces water at the coil, drain tray and condensate route.
Persistent odour, water leakage or poor drainage justifies checking the indoor coil, drain tray and condensate route.
Outdoor units
The outdoor unit needs unobstructed airflow and access for inspection and service.
Refrigerant work
Work that opens, services or recovers refrigerant from stationary equipment containing F gas requires the appropriate qualification in Great Britain. A user-cleanable filter does not make the refrigerant circuit user-serviceable.
Leak-check duties depend on the refrigerant, charge and applicable thresholds. Maintenance requirements and warranty conditions also depend on the exact equipment.
Air-conditioning inspections
In England and Wales, an AC system with an effective rated output above 12 kW must be inspected by an accredited energy assessor at intervals no more than five years apart.
The threshold applies to the system in the building. Individual units below 12 kW are combined where they form one system under one person’s control. An individual unit’s rating below 12 kW does not settle whether the combined system is above the threshold.
Scotland and Northern Ireland have separate requirements. This statutory energy inspection is also separate from maintenance, F-gas leak checks and warranty servicing.
Related entries
Applies to
Heat
Last reviewed
28 Jul 2026