How to Clean Your Air Conditioner

Clean filters are the simplest way to keep air conditioning working well. Dirty filters cut the airflow, so the system works harder, cools and heats less and uses more electricity. Badly blocked filters can also lead to ice on the indoor coil and water dripping from the unit. Cleaning them is quick, and you do not need any special tools.

How Often Should You Clean the Filters?

Most manufacturers recommend cleaning the filters about every two weeks while the system is in regular use, and more often in a dusty room. Your user manual gives the exact advice for your model.

What You Need

• a vacuum cleaner with a soft brush attachment

• lukewarm water, no hotter than 40°C

• a little mild detergent, if your manual allows it

• a soft cloth

How to Clean the Filters

1. Switch the system off with the remote and wait for the louvre to close. Then switch off the power, as your manual describes.

2. Lift the front panel of the indoor unit. On most wall units it hinges upwards from the front edge.

3. Slide or unclip the filters. They are usually one or two fine mesh panels.

4. Vacuum the dust off gently, on the dusty side.

5. If they are still dirty, wash them in lukewarm water with a little mild detergent, then rinse them.

6. Let them dry completely in the shade. Keep them out of direct sunlight and away from heaters, and do not use a hairdryer, as heat can warp them.

7. Refit the filters the right way round, close the front panel firmly and switch the system back on.

Never run the system without its filters, as dust will build up on the coil inside and can damage the unit.

Some units have extra filters, such as deodorising or fine-particle filters, clipped to the main filters. Your manual explains whether these are cleaned or replaced, and how often.

Cleaning the Rest of the Indoor Unit

• Wipe the casing and front panel with a soft cloth dampened with lukewarm water, then dry it with a dry cloth.

• Do not spray water, cleaning products or air freshener into the unit. There are electrical parts inside.

• Do not use solvents, abrasive cleaners or polish, which can damage the plastic.

• Do not touch the thin metal fins behind the filters. They are sharp and bend easily.

Manufacturers warn against spraying liquids into the indoor unit, so DIY coil cleaning sprays are best avoided. A deeper clean of the coil, fan and drain is a job for an engineer.

Looking After the Outdoor Unit

• Keep leaves, plants and anything stacked against it well clear, so air can flow freely.

• Brush leaves and debris off the outside gently.

• Do not use a pressure washer on it.

• Do not cover it if you use the system for heating. See our guide to air conditioning outdoor units.

What a Professional Clean Includes

Filters catch most of the dust, but over time dirt and mould build up deeper inside the unit, on the coil, on the fan and in the drain tray. That needs an engineer with the right tools. Every service we carry out includes cleaning the condensate tray and line, testing the drain pump, cleaning and sanitising the indoor coil, cleaning the filters and checking for refrigerant leaks.

We recommend a service every year, or twice a year if you use the system for heating. See our air conditioning servicing page.

Signs Your System Needs More Than a Filter Clean

• a musty or damp smell when it starts up

• weak airflow, even with clean filters

• water dripping from the indoor unit (see air conditioner leaking water)

• black spots on the louvres or inside the air outlet

• the room takes longer to cool or heat than it used to

Our guide to the top signs your AC system needs repair covers other warning signs.

Frequently Asked Questions

Can I wash air conditioner filters in the dishwasher?

No. Dishwashers run hotter than 40°C, which can warp the filters, and they use strong detergents.

Do air conditioner filters need replacing?

The main mesh filters are designed to be washed and reused. Replace them if they are torn or damaged. Some extra filters, such as deodorising filters, are designed to be replaced, and your manual will say which.

Is it safe to clean the inside of the unit myself?

Clean the filters and wipe the casing only. Do not open the casing or take the unit apart. Leave the deeper clean to an engineer.

If your system needs a deep clean or a service, call 01772 288651 or use the form below and we will arrange a visit.

Last updated: November 2026.