Cleaning and maintaining a portable air conditioner

The air filter catches dust, pollen and hair. Clogged, it chokes the airflow: the unit cools less, the fan strains and gets louder, and the running cost climbs. It is by far the maintenance that matters most, and the most neglected.

• Clean the filter every two weeks in heavy use.
• Remove it, vacuum off the dust, then rinse in lukewarm water if the maker allows.
• Let it dry fully in the shade before refitting: a damp filter breeds mould.
• Never run the unit without the filter: the dust would then clog the heat exchanger, which is far harder to clean.

As it cools, the unit pulls moisture out of the air, which becomes water. Many models evaporate it automatically, but in very humid weather an internal tank can fill and trigger a safety cut-out. Empty it as the manual says, especially at the end of the season.

Water left sitting in the tank for a long time can smell musty. Before storage, run the unit on fan-only mode for half an hour to dry the inside out, then fully empty any remaining reservoir.

The exhaust hose and the rear grille collect dust and fluff that block the warm air. A quick vacuum over the grilles and a damp cloth on the hose, once or twice a season, is enough to keep the airflow up.

While you are there, check the window kit: foams and seals compress over time. A seal that has loosened lets warm air in and quietly drags down the performance without you noticing.

How you store the unit at the end of summer decides its state in spring. A careless job — damp or thrown in a heap — is paid back in smells, lost parts and avoidable faults.

• Clean the filter and dry the inside on fan mode before storing.
• Empty any remaining condensate and leave the tank perfectly dry.
• Coil the hose without a sharp kink and store the window kit with the unit.
• Cover it with a dust sheet in a dry place, away from dust.
• Keep the manual and adaptors together: those are the parts most often lost between seasons.