The short answer
A service keeps an air-con system efficient, reliable and legal. A typical visit costs roughly £80–£150 per indoor unit and covers cleaning filters and coils, checking the refrigerant charge and electrics, clearing the condensate drain and testing performance. Refrigerant work and any re-gas must be done by an F-Gas-certified engineer — it is illegal otherwise. Larger systems also carry a legal leak-check duty above set refrigerant thresholds.
Servicing is the quiet work that keeps an air-conditioning system cooling well, running cheaply and within the law. This guide explains exactly what a competent engineer does on a visit, why each task matters, what it costs, and where legal duties such as F-gas leak-checks come in — so you can tell a real service from a quick wipe of the filters.
Servicing at a glance
- Typical cost £80–£150 per indoor unit
- Domestic interval About once a year
- Who must do refrigerant work An F-Gas-certified engineer
- Core tasks Clean, check charge, test, clear drain
- Legal duty Leak-checks above set F-gas thresholds
- Main benefit Efficiency, reliability and warranty
Why an air-con system needs servicing
An air-conditioner is a refrigerant heat pump that moves heat out of a room. Over time, dust clogs its filters and coils, the condensate drain silts up, electrical connections loosen and the refrigerant charge can drift. Each of those quietly steals efficiency: a fouled filter forces the fan and compressor to work harder for less cooling, raising your running cost and shortening the unit’s life. Regular servicing reverses that drift — it restores airflow, confirms the system holds the right charge, and catches small faults before they become expensive breakdowns. It is also commonly a condition of the manufacturer’s warranty, so skipping it can void cover on a unit that may have cost several thousand pounds to install.
There is a hygiene dimension too. Because the system continually draws humid room air across a cold coil, the inside of an unserviced unit is a damp, dusty place where mould and bacteria thrive — the source of the musty smell that many neglected systems develop. A service cleans those surfaces and clears the drain, which keeps the air you breathe fresher and prevents the water leaks that a blocked drain causes. In short, servicing protects four things at once: efficiency, reliability, hygiene and the warranty. For a single small split that runs only in summer the stakes are modest; for a year-round or commercial system they are considerable, which is why heavier-used systems are serviced more often.
What a proper service includes
A competent service is methodical. The engineer works through the indoor and outdoor units, cleaning, measuring and testing rather than just glancing over the equipment. The core tasks are consistent across brands.
- Filters and coils — clean or replace filters and clean the indoor evaporator and outdoor condenser coils to restore airflow.
- Condensate drain — clear and flush the drain and check the pump, the most common cause of water leaks.
- Refrigerant charge — measure operating pressures and temperatures to confirm the charge is correct and there is no obvious leak.
- Electrical checks — inspect connections, contactors and controls, and confirm safe current draw.
- Performance test — run the system in cooling (and heating, if reverse-cycle) and verify it reaches temperature.
| Task | Why it matters | If neglected |
|---|---|---|
| Clean filters & coils | Restores airflow and efficiency | Higher bills, weak cooling, icing |
| Clear condensate drain | Prevents water overflow | Leaks, damp, mould |
| Check refrigerant charge | Confirms cooling capacity | Poor cooling, compressor strain |
| Inspect electrics | Safety and reliability | Trips, faults, fire risk |
The F-gas leak-check duty
Refrigerant is a fluorinated greenhouse gas, and GB F-gas law treats it seriously. Only an F-Gas-certified engineer may handle refrigerant — checking the charge, topping up or recovering it — and any company doing that work must be F-Gas-registered. On top of that, systems containing refrigerant above set thresholds carry a legal duty to be leak-checked at intervals that depend on the charge size, with records kept. That duty bites mainly on larger and commercial installations rather than a single small domestic split, but it is a genuine legal obligation, not a marketing add-on.
What it costs and what to expect
A routine service typically costs around £80–£150 per indoor unit, with multi-unit homes and businesses often getting a per-unit discount when several units are done on a single visit. Many people take out an annual maintenance contract that bundles the service with priority callouts and sometimes a small parts allowance, which can be worth it for a system you rely on. The price reflects time, skill and the certified status of the engineer rather than just parts, so a quote far below the range usually signals a cursory once-over rather than a real service. For the wider picture on pricing, see air-con servicing cost, and for how often to book it, see how often to service air con.
A good engineer will leave you a written record of the operating readings, the refrigerant charge status and any recommendations, and on larger systems the F-gas leak-check documentation. Keep these — they matter both for the manufacturer’s warranty, which usually requires evidence of regular servicing, and for legal compliance on bigger systems. If the service uncovers a fault, expect the engineer to explain it plainly and quote separately rather than fixing the unexpected without telling you. This page is general information, not a substitute for a site-specific survey or a quote from a certified installer.
Due an air-con service?
Get matched with an F-Gas-certified engineer who can service your system properly and keep your warranty and compliance intact. A quote costs nothing.
Frequently asked questions
How much does an air-con service cost?
Typically around £80–£150 per indoor unit. Homes and businesses with several units on one visit often pay a lower per-unit rate.
Can I service my air-con myself?
You can clean the accessible filters yourself, but anything involving the refrigerant circuit is legally restricted to an F-Gas-certified engineer. DIY refrigerant work is illegal.
Does servicing protect my warranty?
Usually yes. Most manufacturers require evidence of regular servicing to keep the warranty valid, so a missed service can void cover.
Is a leak-check the same as a service?
Not quite. A service is general maintenance; a leak-check is a specific legal duty for systems above set refrigerant thresholds and is recorded separately.
Sources & further reading
- GOV.UK — F-gas: guidance for users, producers and traders
- The Fluorinated Greenhouse Gases Regulations 2015 (GB F-gas)
- REFCOM / F-Gas Register — certified company requirements
- Energy Saving Trust — heating and cooling efficiency
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.