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How to clean your air conditioner

Cleaning the filters can improve air quality and efficiency.

woman checking filters on air conditioner
Last updated: 24 January 2020

It's important to clean your air conditioner to maintain good air quality in your home. Filters inside air conditioners are designed to catch dust (and sometimes other pollutants such as pollen and bacteria), but if not cleaned regularly they can clog up and collect moisture and even mould. That's not good for you or for your air conditioner.

Regularly cleaning your air conditioner will also mean better energy efficiency and lower running costs. The more clogged the dust filters and the interior of the machine, the harder it has to work (and the more energy it uses) to move the air, as well as cool or heat.

The following advice is based on split-system air conditioners (the most common type in Australian homes) but it broadly applies to ducted and wall-window models too.

Check the instructions

Your air conditioner should have come with an instruction manual that details how to access and clean the air filters and any other user-maintainable parts. If you don't have the book any more, you may be able to download a copy from the manufacturer's website.

Make sure the unit is turned off at the wall before you do any maintenance on it.

How to clean the indoor unit (filters and louvres)

Clean the indoor unit dust filters

The indoor air conditioner unit has dust filters that need regular cleaning. The more clogged the filter, the harder the air conditioner has to work to push air through it. That can mean higher running costs.

It's usually a simple matter of popping open the plastic cover and removing the filter (there may be more than one).

Manufacturers usually recommend that you clean the dust filters every few weeks, but it really depends how often you use the air conditioner. Simply put, the more you use it, the more often you should clean the filters. At the least, aim to clean them a couple of times a year. For example, if you mainly use the unit in summer, clean the filters in spring so it's ready for the peak season, and again when the hot season is over.

Some models also have an air purification filter (such as an ionising filter) that can be removed and cleaned; this type of filter will eventually need to be replaced, perhaps every year or two, depending on usage. Check the instructions for how to clean or replace this filter.

  • Take the dust filters outside for a good brush or shake. They can usually also be vacuumed for a thorough clean; use the vacuum cleaner's dusting brush head if you have one. 
  • If the dust filters are very dirty and grimy, you can wash them in warm water with some mild detergent and rinse them clean. Make sure they are completely dry before putting them back in the unit.

How to clean your air conditioner's louvres

You may also be able to remove the indoor unit's louvres (the oscillating blades that direct the air flow). Give them, and the space behind them inside the unit, a thorough clean with a dry cloth or with the vacuum cleaner. Again, make sure the unit is powered off before you do this.

How to clean the outdoor unit

Keep the outdoor compressor unit clear of surrounding grass and plants, and brush away dust, leaves and cobwebs regularly. 

Running a vacuum cleaner over the air intake can help clear dust from inside.

We don't recommend that you open up the unit to clean its internal components; leave that to a professional service.

Getting your air conditioner professionally serviced and cleaned

Your air conditioning system should be professionally serviced regularly – the service person will check the refrigerant gas levels, test the thermostat and make sure all the internals are in good condition. This will keep the unit running for many years.

Some manufacturers recommend the air conditioner should be serviced once a year. Others say that as long as you follow the instructions and regularly clean the filters and units, you'll only need to have the air conditioner serviced if a fault develops.

We asked CHOICE members about their air conditioner cleaning habits. Most said they clean the filters a few times each year, but only call for a service every few years or when the unit develops a fault. If in doubt, check the manual for your model or call the manufacturer for their advice.

Professional cleaning

You can have your air conditioner cleaned by a professional. A maintenance service should include cleaning of internal components such as coils, fins and drainage.

If you live in a very dusty or humid environment, and use your air conditioner frequently, you might be surprised at how much dust and mould can build up inside the air conditioner. This can lead to the unit losing performance as it clogs up, mould spores being blown into your home, and water leakage if the indoor unit's drainage pipe gets blocked by gunk. Regular cleaning of the dust filters and louvres, and running a 'dry out' program if the unit has one, will help avoid this, but an occasional professional service and clean may still be a good idea.

Air conditioner cleaning cheat-sheet

Every use

  • Run the 'dry out' program if your air conditioner has it. This evaporates the moisture that's condensed on the heat exchanger, preventing mould and foul odours.

Bi-annually

  • Clean and/or replace the dust filter screens in the indoor unit of a split-system, or as per the instructions for your ducted system. (Do this more often if your air conditioner is always on, you live in a very dusty environment or you experience a noticeable drop in performance.)
  • Clean any extra filters, such air purifying filters, as per the instructions.
  • Wipe down the indoor unit or any ducts or vents with a soft damp cloth, both inside the unit (as far as you can safely reach) and the exterior.

Annually

  • Clean the outdoor unit and remove vegetation/obstructions/spiders as necessary.

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