A pre-summer service is a planned visit while engineers still have diary space, not a panic call on the first 30C Friday. It should cover filters, drains, the outdoor coil, a visual look at electrics and a performance check. Refrigerant work happens only if there is evidence of a problem, and only by an F-gas certified company. Book it in spring for a home, and earlier if a shop cannot trade in a hot spell. Larger systems may also need the statutory inspection described on GOV.UK, which is a different appointment.
Seeds in the outdoor coil before August
Cooling season punishes dirty filters, blocked condensate pumps and outdoor coils packed with seeds. A spring visit clears those before they become a warm-room callout. The engineer should run the system in cooling, check that air actually leaves the indoor unit cold, and confirm water is leaving the drain rather than the wall.
A written note, not only a dated sticker
Ask for a written note of what was cleaned, what was left, and any part that will fail before August. A sticker with a date and no findings is a weak record. Keep it with the commissioning sheet.
Filters and covers you can clear safely
Wash a domestic mesh filter if the manual says you may, and make sure the outdoor unit is not boxed in by winter covers, bikes or a new fence.
- Clear leaves you can reach safely with the system off.
- Do not jet the electrical side of the condenser and do not open panels.
- Write down noises, smells, slow cooling and any stain on the plaster.
Every indoor unit, not only last year's drip
Book around trading. A cassette over a sales floor is easier to service on a Monday morning than on the Saturday before a bank holiday. Include every indoor unit, not only the one that dripped last year. Kitchen and bakery units need a sterner filter look than a back office. Shops that cannot close on a whim should book earlier and name the trading hours on the order. If the system is above the rated-output threshold published on the GOV.UK air conditioning inspections page, schedule that inspection as well. A maintenance clean does not replace it. The operator, in the F-gas sense, should know which diary entry is which.
April diaries and a low-hundreds illustration
As a 2026 illustration, a straightforward domestic service is often talked about in the low hundreds of pounds including VAT, and a small shop with several indoors costs more because of time, access and out-of-hours rules. June prices and waiting times are worse than April prices. The figure moves with travel, pumps and any genuine repair. Book in spring, before the first hot spell fills the diaries.
A failed pump is a follow-on, not a top-up
That list of symptoms is more useful than asking for a regas by default. Adding refrigerant to a tight system is not maintenance. Investigating a loss of charge is F-gas work for a certified firm, and this page does not describe how it is done. GOV.UK publishes certification for companies working on equipment containing F-gas. A sound system is cleaned, checked and left with its charge untouched. Refrigerant is handled by a certified company only when there is a reason, and it is not a routine top-up product. If the visit finds a failed pump, a dead isolator or a leak, approve the follow-on work with the same paperwork standard. Venting refrigerant is illegal. Recovery and repair stay on the certified side of the trade. Electrical concerns go to a competent electrician. Energy Saving Trust's air-to-air pages describe the equipment being cleaned. They are not a service sheet.
Frequently asked questions
When should I book a pre-summer service?
In spring, before the first hot spell fills the diaries. Shops that cannot close on a whim should book earlier and name the trading hours on the order.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.