Learning how to clean aircon filters is the simplest, cheapest way to keep your unit cooling efficiently and your power bill down. A dirty aircon filter is the single most common reason a unit stops cooling properly — and the easiest thing to fix yourself. Cleaning it takes about 15 minutes, needs no special tools, and should be done every few weeks to keep your air conditioner running efficiently. This guide walks you through it for split and midwall units, the type found in most South African homes and offices.
Why cleaning your aircon filter matters
The filter traps dust, pollen and pet hair before they reach the cooling coils. When it clogs up:
- Cooling drops — airflow is restricted, so the room takes longer to cool.
- Power bills climb — a blocked filter forces the unit to work harder, using up to 15% more electricity.
- Air quality suffers — a dirty filter recirculates dust and allergens, which matters during Highveld pollen season.
- The unit wears out faster — restricted airflow can freeze the coils and strain the compressor.
In short: a clean filter means colder air, lower bills and a longer-lasting aircon.
How often should you clean it?
- Every 2 weeks during heavy summer use, or if you have pets or live near a dusty road.
- Once a month for normal household use.
- Before you switch it on at the start of each cooling season.
What you’ll need
- A vacuum cleaner with a brush attachment
- Lukewarm water and a mild dish soap
- A soft cloth or sponge
- A dry towel
- A step stool (most midwall units sit high on the wall)
How to clean aircon filter units on a split or midwall system
- Switch off and unplug. Turn the unit off at the remote, then at the wall or isolator. Never clean a filter on a running unit.
- Open the front panel. Lift the hinged front cover upward — it will click and hold open, revealing one or two flat mesh filters.
- Slide out the filters. Gently push each filter up to release the tab, then pull it down and out. Note which way it faces.
- Vacuum off loose dust. Hold the filter over a bin and vacuum the dusty side with the brush attachment.
- Wash it. Rinse under lukewarm running water. For heavy grime, soak in water with a little dish soap, then rinse clean. Never use hot water or harsh chemicals.
- Dry completely. Air-dry fully in the shade. Never refit a damp filter — moisture breeds mould.
- Wipe the front panel. While the filter dries, wipe the cover and visible vanes with a damp cloth.
- Reseat and close. Slide the dry filter back the way it came out, click the panel shut, and switch the unit on.
You should immediately notice stronger, cooler airflow.
Cleaning a portable or window unit
The principle is the same: switch off, locate the filter (usually a clip-out panel on the back or side), vacuum, wash in mild soapy water, dry fully and refit. Check your unit’s manual for the exact filter location.
Common mistakes to avoid
- Using hot water or chemicals — these damage the delicate mesh.
- Refitting a wet filter — invites mould and a musty smell.
- Forgetting the second filter — many units have two; clean both.
When to call a professional
Cleaning the filter is easy DIY, but it only handles the dust you can see. Over time the evaporator coils, drainage line and fan collect grime and mould a filter rinse won’t touch — and refrigerant gas can only be checked by a qualified technician. If your aircon still cools poorly after a clean, smells musty, drips water, or it’s been over a year, it’s time for a service.
Van Biljoens has serviced and installed air conditioning across Pretoria since 1956. Our technicians do deep cleans, regas and full system checks. Book a service or request a quote or call us on 012 330 0421.
Frequently asked questions
How often should I clean my aircon filter?
Every two weeks during heavy summer use, or once a month for normal use. Dusty areas and homes with pets need more frequent cleaning.
Can I wash an aircon filter with water?
Yes. Rinse it under lukewarm water with a little mild dish soap for stubborn dirt, then let it dry completely before refitting. Avoid hot water and harsh chemicals.
What happens if I never clean my aircon filter?
The unit cools poorly, uses more electricity, recirculates dust, and risks the coils freezing or the compressor failing — leading to expensive repairs.
How long does an aircon filter take to dry?
Around 1 to 3 hours air-drying in the shade, depending on humidity. Never refit it while still damp.
Does cleaning the filter improve cooling?
Yes — a clean filter restores airflow, so the room cools faster and the unit runs more efficiently, often within minutes.
