What an air conditioning service includes
A proper air conditioning service is a structured 45–90 minute inspection of everything that affects efficiency, hygiene and reliability — not a quick filter rinse. Here is the full checklist a competent F-Gas certified engineer works through, how long it takes, and the signs you have been short-changed.
The 10-point air conditioning service checklist
Manufacturers publish their own schedules and engineers have their own job sheets, but a full domestic or light-commercial service covers the same ground: cleaning protects airflow and hygiene, the refrigerant and electrical checks protect the compressor, and the report protects your manufacturer warranty. Expect £75–£150 per unit for a one-off visit in 2026 (see the servicing cost guide). Check your engineer's report against this.
| # | Task | What the engineer does | Why it matters |
|---|---|---|---|
| 1 | Filters | Washes or replaces dust and deodorising filters; checks frame and seals | Blocked filters cut airflow, raise running costs and let dust reach the coil |
| 2 | Indoor coil and blower | Cleans the evaporator fins and, where access allows, the blower wheel; checks for damage and growth | A dirty coil cannot transfer heat or dehumidify and is the usual source of musty smells |
| 3 | Condensate drain | Flushes the drain line and tray, tests any pump, treats against slime | Blocked drains cause the most common call-out: water dripping indoors |
| 4 | Refrigerant pressure and leak check | Connects gauges, compares pressures with the manufacturer's chart, checks joints with a leak detector | Low charge means a leak — illegal to simply top up — and starves the compressor |
| 5 | Electrical connections | Isolates supply, tightens terminals, inspects contactors and capacitors, measures running current | Loose or corroded connections cause intermittent faults and can overheat |
| 6 | Fans and motors | Checks blades for damage, listens for bearing noise, confirms speeds | A failing fan motor shows as noise long before it fails |
| 7 | Thermostat, sensors and controls | Tests remote and wired controllers, checks room and coil sensors read correctly | A sensor a degree out makes the unit short-cycle or run constantly |
| 8 | Outdoor unit | Clears debris, cleans the condenser coil, checks bracket, pipe insulation and clearances | If the outdoor coil is choked the whole system loses capacity |
| 9 | Test run | Runs cooling and heating, measures the supply/return air temperature split | Proves the system performs to specification |
| 10 | Report | Records readings, work done, faults and recommendations; notes the F-Gas certificate number | Your warranty evidence and next year's baseline |
Typical scope for split and multi-split systems. Ducted and commercial systems add duct, damper and control checks; systems above the F-Gas thresholds add a logged leak check — see how often air conditioning should be serviced.
How long it takes — and when to book
Allow 45–90 minutes per indoor unit. A clean, accessible single split sits at the bottom of the range; a unit unserviced for two or three years, or a condenser needing a proper coil wash, sits at the top. On a multi-split the outdoor unit is checked once, so each extra indoor unit adds roughly 30–45 minutes. Book in spring for cooling, before engineers fill up with breakdowns; units used for winter heating benefit from a second visit in autumn.
Anything found during the visit — a leak, a failed capacitor, a seized drain pump — is a repair, priced separately, and a good engineer quotes it first. Our repairs page covers common faults and the re-gas guide explains what must happen before refrigerant goes back in.
What a bad service looks like
Customers rarely watch the whole visit, so servicing is easy to do badly. Signs you paid for a service and got less:
- In and out in 15–20 minutes. That is a filter rinse and a wipe of the casing.
- No gauges, no leak detector. If the engineer never connected to the outdoor unit's service ports, the refrigerant circuit was not checked.
- A "top-up" offered as routine. Working systems do not use refrigerant; adding gas without fixing a leak is illegal under the F-Gas regulations, and you will pay again next year.
- Outdoor unit untouched. If the condenser is still full of leaves afterwards, half the job was skipped.
- No written report. Nothing to show a manufacturer if a claim arises, and nothing to compare next year's readings against.
- No F-Gas credentials. Anyone handling refrigerant must be F-Gas qualified, and companies registered with a body such as REFCOM — see our F-Gas certification guide.
All the engineers we match you with are vetted and F-Gas certified. To have the checklist done every year automatically, see what a maintenance contract costs; multi-unit sites have extra obligations covered on our commercial air conditioning page.
Frequently asked questions
Book a proper service
Tell us how many units you have and where, and we match you with vetted, F-Gas certified engineers near you who quote for the full checklist above. Free, no obligation.