How Often Should Air Conditioning Be Serviced?

How often a home air conditioning system needs servicing

For a wall-mounted split or a small multi-split in a house or flat, once a year is the working answer. Nothing in UK law compels a homeowner to service a domestic air conditioning system on a fixed interval. What drives the annual cycle is the manufacturer's warranty and the plain fact that filters and coils load up with dust over a season of use.

Autumn is a sensible slot. The system has just come off its hardest months, and if it also runs in heating mode you want a fault found now rather than in January. If you only ever use it for cooling, booking in the shoulder season also means you are not competing with everyone else's emergency callout during the first hot week of summer.

Warranty conditions are the part people miss. Daikin UK's residential warranty page states that a warranty is only valid if annual maintenance is carried out, and that Daikin reserves the right to ask for proof it was done. Other manufacturers word it differently, and enforcement varies in practice, but the pattern is consistent enough that you should read your own paperwork and keep every service record. A missing record is a cheap reason for a manufacturer to decline an expensive claim.

If your system is already not performing, a service is not the right first call. Air conditioning repair covers diagnosis, which is a different visit at a different price. If you are not sure which you need, request a quote and tell us what the system is doing.

What the law actually requires

Mandatory leak checking under the GB F gas rules is not triggered by the age of your system or by a calendar. It is triggered by how much refrigerant the system holds, converted into tonnes of carbon dioxide equivalent.

GOV.UK's guidance on checking F gas equipment for leaks sets the intervals. Equipment holding the equivalent of 5 to under 50 tonnes of CO2 must be checked at least once every 12 months. From 50 to under 500 tonnes, at least every 6 months. At 500 tonnes or more, an automatic leak detection system must be fitted. Fitting automatic leak detection doubles the permitted gap between checks.

The thresholds are easier to read in kilograms. GOV.UK's own table puts 5 tonnes of CO2 equivalent at 2.4kg of R-410A. For R-32, which GOV.UK lists at a global warming potential of 675, 5 tonnes works out at roughly 7.4kg of refrigerant. A single-room domestic split typically holds around a kilogram, so it sits well below the threshold and no mandatory leak check applies. Larger multi-splits, VRF and most commercial installations are a different matter, and plenty of them are comfortably in scope.

Two things follow from that. First, being under the threshold means no mandatory leak check. It does not mean no servicing. Second, where the duty does apply it sits with whoever operates the equipment, not with the engineer who turns up. If a leak is found it must be repaired as soon as possible and re-checked within a month, and records have to be kept.

Commercial buildings and TM44 inspections

There is a third obligation that catches business premises in England and Wales, and it is not a service either. Under the Energy Performance of Buildings Regulations, an air conditioning system with an effective rated output of more than 12kW must be inspected at least every five years by an accredited energy assessor, with a report produced. Individual units serving one building count towards that 12kW together, which is how offices running several smaller systems end up in scope without realising it.

A TM44 inspection assesses efficiency and sizing and recommends improvements. It does not clean your filters, and a routine service does not satisfy it. Scotland and Northern Ireland handle air conditioning inspections under their own regulations, so confirm the position for your building rather than assuming the England and Wales rule travels.

If you run offices, retail or hospitality, commercial air conditioning sets out what our network covers and where these duties usually land.

What an annual service should cover

Expect filters cleaned or replaced, the indoor coil and blower checked, and the condensate tray and drain cleared. Blocked condensate is one of the most common causes of water appearing where it should not, and it is entirely preventable. Outside, the coil and fan should be cleaned and checked for damage and for anything that has grown or been stacked against them since last year.

The engineer should check electrical connections and controls, read operating pressures and temperatures, and run the system in both cooling and heating if it does both. Any work on the refrigerant circuit is legally restricted to F-Gas certified engineers. Our vetted contractors are F-Gas certified, and you are entitled to ask to see that qualification before anyone touches the system.

Ask for a written record at the end of the visit, with the date, what was done and any readings taken. That document is what protects a future warranty claim, and it is what the next engineer will want to see. If pipework or drainage comes up during the visit, air conditioning pipework and condensate drainage explains what they are looking at.

What it costs, and what skipping it costs

Checkatrade's 2026 cost guide for home and office air conditioning servicing puts a service at roughly £70 to £120 per unit, with around £80 as a typical figure. Location moves that, and London and the South East sit at the higher end. On the coast, in Southampton and similar places, salt-laden air makes cleaning the outdoor coil more of a priority than it is inland. Multiple units, a maintenance contract, or a system that needs work beyond a routine service will all change the number. Your actual price comes from the contractor, not from a national average.

The cost of skipping it is less visible. Dirty filters and coils cut the amount of heat the system can move, so it runs longer for the same result and your electricity bill absorbs the difference. A blocked drain puts water into a ceiling. A slow refrigerant loss degrades performance for months before it becomes an obvious fault, while the compressor works harder than it was built to. And a warranty claim declined for want of a service record turns a covered repair into an invoice.

Landlords have an extra reason to keep the paperwork tidy, because the record travels with the property and answers the tenant question before it is asked. Air conditioning for landlords covers the rest of that.