Cleaning and maintaining an air conditioner: when, how and what it costs

What you do: the filters

Open the front cover, remove the mesh filters, wash in lukewarm water, dry and refit. Every 2–4 weeks in season, more often with pets or a dusty street. A clogged filter is the most common cause of "it does not cool like before" and up to 15% higher bills.

What you do: housing and louvers

Wipe with a damp cloth. Avoid spray "coil cleaners" unless the maker recommends them. Check the condensate hose outside is not kinked.

What the technician does: annual service

Once a year before the season:

• Chemical or steam cleaning of the indoor coil and fan
• Cleaning the drain pan and drain of biofilm (the source of smells)
• Cleaning the outdoor coil
• Checking pressures and temperatures; topping up refrigerant only if needed
• Checking electrical connections, capacitors and the outdoor mounting

How often and what it costs

Homes once a year, offices twice. The price is in our service tariff by unit type. A skipped service is not a saving: a dirty coil costs 10–20% more electricity all season and most makers require maintenance for the warranty.

Symptoms

Musty smell: biofilm, service needed. Dripping indoors: blocked drain or a frozen coil from a dirty filter. Weak airflow: filters or fan. Ice on the outdoor pipes in summer: low refrigerant, call a technician.