Short answer: Clean the indoor unit's filters every few weeks in heavy use, keep the outdoor unit clear of leaves and plants, check the drain is running in summer, and book a professional service once a year to clean coils, test drains and check performance.
Every few weeks in season
Switch off, open the front panel, slide out the filters, vacuum or rinse them in lukewarm water, let them dry fully, and refit.
Every month
Clear leaves and debris from around the outdoor unit and keep at least 30 cm clear on all sides. Check the condensate drain outlet is not blocked.
Once a year
Professional service: coil cleaning, drain flush, electrical checks and performance readings. Larger multi-split systems may also need a legal leak check.
Warning signs
Water dripping indoors, musty smells, ice on pipes, unusual noises, or reduced cooling. Switch off and call us rather than running it.
Related services
More guides
- How much does air conditioning cost to install in the UK?
- How much does air conditioning cost to run?
- What size air conditioner do I need?
- Fixed split or portable air conditioning?
- Do you need planning permission for air conditioning?
- The £2,500 grant for air-to-air heat pumps explained
- F-gas rules: what homeowners need to know
- R32, R410A and R22: refrigerants explained
- Is air conditioning the same as a heat pump?
- What happens on air conditioning installation day
- Air conditioning noise and your neighbours
- Can you fit air conditioning in a listed building?
- Air conditioning in a flat: leases, freeholders and planning
- Keeping a home cool in a heatwave
- Multi-split or separate single systems?
Reviewed October 2026. Rules and prices change; check the date and ask us if anything is unclear.