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Advice . 11 October 2026

How often should air conditioning be serviced?

Once a year is the rule for most homes. Here is why, what a service should include, and the warning signs that mean you should not wait.

How often should AC be serviced?

Air conditioning is easy to forget about until it stops working properly. A regular service keeps it running efficiently, keeps the air it delivers clean and protects your warranty. Here is a straightforward guide to how often, and why.

The short answer

  • Homes: once a year.
  • Offices, shops and salons: once a year as a minimum, twice a year where systems run most days.
  • Restaurants, kitchens, gyms and dusty environments: twice a year or more.
  • Server and comms rooms: at least twice a year, because the equipment they protect depends on them.

Why it matters

Efficiency and running costs

Dust on the filters and coils makes the system work harder to move the same amount of heat. That costs you money in electricity, in summer and in winter if you use it for heating.

Air quality and smells

Indoor units handle a lot of air and pull moisture out of it. Without cleaning, the coil, fan and drain tray can build up dirt and biological growth. That is the usual cause of the musty smell some people notice when a system starts up.

Water leaks

Blocked condensate drains are one of the most common faults. Water backs up and drips from the indoor unit, often onto walls and furniture. Flushing the drain during a service prevents it.

Warranty

Many manufacturers require regular maintenance by a qualified engineer for extended warranties to remain valid. A written service record is your evidence.

Legal leak checks for larger systems

Under the F-Gas Regulations, systems containing refrigerant above a certain CO2 equivalent threshold must be leak checked at set intervals by a certified engineer, and the checks must be recorded. Many commercial systems are covered by this.

What a thorough service includes

  • Filters removed, cleaned and refitted.
  • Indoor coil and fan cleaned and treated.
  • Condensate tray and drain line checked and flushed, and any condensate pump tested.
  • Outdoor unit coil cleaned and the fan, mountings and surroundings checked.
  • Temperatures and pressures recorded to confirm the system is performing correctly.
  • Pipework insulation, trunking and visible electrical connections inspected.
  • A written record for each system.

Signs your system needs attention now

  • It is not cooling or heating as well as it used to.
  • There is a musty or damp smell when it starts.
  • Water is dripping from the indoor unit.
  • Ice is forming on the pipework or the outdoor unit in cooling mode.
  • It is noisier than it used to be.

Cleaning filters between services

You can help by cleaning the indoor unit filters yourself every few weeks during heavy use. Most lift out easily and can be rinsed in lukewarm water and left to dry. Leave the coil, drain and outdoor unit to an engineer.

If your system is due a service, or you are not sure when it was last done, send us the make and model through the quote form and we will get back to you with a booking.

Written by Zakaria Sinjab, F-Gas Category 1 certified engineer and director of Zephyr Climate Ltd.

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