The short answer
Good maintenance is mostly keeping airflow clear — plus a yearly professional service. You can safely clean filters, keep the outdoor unit clear, wipe surfaces and run fan-only before shutdown to dry the coil. Leave anything involving refrigerant, electrics or deep coil cleaning to an F-Gas-certified engineer, who should service the system about once a year (£80–£150 per unit). Done well, maintenance cuts bills, prevents breakdowns and protects the warranty.
Air-con maintenance splits cleanly into two halves: the simple, safe jobs you can do yourself between visits, and the technical work that the law and good sense reserve for a certified engineer. This guide sets out both — the DIY habits that keep your system efficient and the professional tasks that keep it reliable and legal — so your air-con lasts longer and costs less to run.
Maintenance at a glance
- Do yourself Clean filters, clear outdoor unit
- Filter check Every few months; monthly in heavy use
- Leave to engineer Refrigerant, electrics, deep clean
- Professional service About once a year
- Service cost £80–£150 per unit
- Payoff Lower bills, fewer breakdowns
The jobs you can safely do
Most of the maintenance that keeps an air-con system efficient is about airflow, and you can do it yourself with the unit switched off. None of it involves opening the refrigerant circuit or the electrics. Done regularly, these small habits make a real difference to running cost and reliability.
- Clean the filters — the single most valuable job; remove, wash or vacuum and refit. A clogged filter slashes cooling and raises bills.
- Keep the outdoor unit clear — remove leaves and debris and keep plants, furniture and bins away so it can dump heat freely.
- Wipe the indoor unit — dust the casing and vents, taking care not to damage the fins.
- Run fan-only before shutdown — a few minutes dries the coil and helps prevent musty smells and mould.
- Watch the condensate — check the outdoor drain outlet is clear so water doesn’t back up.
| Task | You or engineer | How often |
|---|---|---|
| Clean filters | You | Monthly to quarterly |
| Clear outdoor unit | You | Seasonally |
| Deep coil clean | Engineer | At annual service |
| Check refrigerant charge | Engineer | At annual service |
| Electrical inspection | Engineer | At annual service |
What to leave to a certified engineer
The technical half of maintenance is not optional DIY — some of it is legally restricted. Anything that touches the refrigerant circuit — checking the charge, leak-testing, topping up — may only be done by an F-Gas-certified engineer. So can electrical inspection, deep cleaning of the internal coil, and any fault diagnosis inside the unit. An annual professional service rolls these together — see servicing explained. Trying to do refrigerant work yourself is illegal and risks injury and damage.
A simple test for whether a job is yours or the engineer’s: if it needs you to open the sealed parts of the unit, use refrigerant, or work on the wiring, it is the engineer’s. Cleaning a removable filter, brushing leaves off the outdoor unit and wiping the casing are all on the safe side of that line; everything beyond is not. Sticking to that boundary keeps you safe and legal while still letting you do the bulk of the day-to-day upkeep that matters most for efficiency.
Why maintenance pays for itself
Maintenance is not just tidiness — it has a direct financial payoff. A clean, correctly charged system uses less electricity to deliver the same cooling, so good maintenance shows up on your bills — see running cost. It also prevents the small problems that turn into expensive breakdowns, extends the system’s life, and keeps the manufacturer’s warranty valid, which usually depends on evidence of regular servicing. A neglected system, by contrast, quietly loses efficiency, fails sooner and may leave you without warranty cover when you need it most.
A simple maintenance routine
A workable routine is straightforward: check and clean the filters every few months (monthly in heavy or dusty use), clear the outdoor unit each season, run fan-only before shutting down, and book a professional service once a year — in spring is ideal, before the cooling season. Keep the service records for warranty and, on larger systems, for F-gas compliance — see how often to service. Tying the yearly booking to a fixed calendar point, such as the clocks changing, stops it slipping, and a quick filter check at the start of each warm spell keeps the system ready when you need it most. The whole routine takes very little effort for a large payoff in efficiency, reliability and a longer working life. This page is general guidance, not a maintenance plan for your specific system; a certified installer can tailor one to your equipment and how you use it.
Want your system properly maintained?
Get matched with an F-Gas-certified engineer for an annual service that keeps your air-con efficient, reliable and within warranty. A quote costs nothing.
Frequently asked questions
What air-con maintenance can I do myself?
Clean the filters, keep the outdoor unit clear of leaves and obstructions, dust the indoor unit and run fan-only before shutdown. Avoid anything involving refrigerant or electrics.
How often should I clean air-con filters?
Every few months in normal use, and monthly in heavy or dusty conditions. Clean filters are the single biggest factor in efficient cooling.
Why does maintenance save money?
A clean, correctly charged system uses less electricity for the same cooling, prevents costly breakdowns, lasts longer and keeps the warranty valid.
Can I check the refrigerant myself?
No. Refrigerant work is legally restricted to F-Gas-certified engineers. Leave charge checks, leak tests and top-ups to a certified professional.
Sources & further reading
- Energy Saving Trust — running cooling efficiently
- GOV.UK — F-gas: guidance for users, producers and traders
- The Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas)
- Manufacturer technical data (Daikin, Mitsubishi Electric) — filter and unit care
This guide is general information, not a site-specific survey or a substitute for a quote from an F-Gas-certified installer. Installation, servicing and refrigerant handling are legally restricted to F-Gas-certified engineers.