20 July 2026

Air-conditioner maintenance: what to do yourself and what to leave

You clean the filters yourself; you never touch the refrigerant. The maintenance routine that protects efficiency and warranty.

Most air-conditioner maintenance is surprisingly simple and yours to do: during the season, take the dust filters out from behind the indoor unit's flap every four to six weeks and clean them with a vacuum cleaner or lukewarm water. Dirty filters are the most common reason a unit cools worse, uses more power or smells musty. Also keep the outdoor unit clear of leaves and dirt, and check that the condensate drain drips neatly while the unit is cooling.

Then there is the work that belongs to the engineer. During a maintenance visit of € 80 to € 150 they clean the heat exchangers and the condensate drain, check the electrical connections and the refrigerant circuit, and measure whether the system still delivers what it should. Advice: once a year with regular use — certainly if you also heat with the unit, because then it runs all year.

Why you never go beyond the filters yourself: the refrigerant in the lines is a potent greenhouse gas, and work on that circuit is legally reserved for F-gas-certified engineers. If you see ice forming on the pipes, the indoor unit leaks water or the system noticeably cools less, leave it alone and have the fault repaired — € 100 to € 250 including diagnosis.

Maintenance is also a warranty matter: many manufacturers require periodic servicing. If you run several systems, or want contract-based climate maintenance for an office or shop, choose a maintenance contract with a fixed frequency. The rates are in the price index.