How to clean an air conditioner filter in a wall unit
Switch the unit off at the isolator, lift the front panel and slide out the mesh filters. Vacuum or rinse them in lukewarm water, let them dry in the shade, then slide them back. Daikin, Mitsubishi Electric and Panasonic all recommend doing this every two weeks, and it's the one cleaning job their manuals leave to you.
- filter clean, in the manuals
- Every 2 weeks
- water, Daikin and Panasonic
- Under 40°C
- extra air-cleaning filters
- 3 to 6 months
- annual service, inc. VAT
- £119
How to clean air conditioner filters, step by step
Switch off
Turn the unit off with the remote and wait for the flap to close. Then switch off the power at the isolator or fused spur.
Open the front panel
Lift the front panel from both sides until it stops or locks open. Some panels lift off completely, like Daikin's Perfera. Others, like Mitsubishi Electric's MSZ-LN, stay on the unit. Your manual shows which kind you have.
Take out the filters
Most mesh filters have a tab in the middle: push or pinch it, lift the filter slightly, then pull it down and out. If extra air-cleaning filters are clipped onto them, unclip those first and clean them separately.
Vacuum or rinse
Vacuum off the dust, or rinse the filters under the tap. Daikin suggests soaking them in lukewarm water for 10 to 15 minutes, with a little neutral detergent if the dust won't shift. Don't scrub with a brush or a hard sponge.
Dry in the shade
Shake off the water and let the filters dry completely, out of direct sunlight. Don't dry them on a radiator or with a hairdryer. Mitsubishi Electric says not to dry parts in direct sunlight or with heat or fire.
Refit and close
Slide the filters back in the right way round, then close the front panel and press it at both sides and in the centre so it closes securely. Replace any filter that's torn or bent out of shape. Then switch the power back on.
How often, by brand
What each manufacturer's user manual says for a current wall unit. Many units have extra filters behind the mesh ones, with their own timings.
| Brand and model | Mesh filters | Extra filters | Water |
|---|---|---|---|
| Daikin Perfera (FTXM-A) | Every 2 weeks | Deodorising and silver particle filters: wash every 6 months, replace every 3 years | Below 40°C |
| Mitsubishi Electric MSZ-LN | Every 2 weeks | Air purifying device and deodorising filter: every 3 months. Replace the deodorising filter if cleaning no longer works | No hotter than 50°C |
| Panasonic TZ and RZ (CS-TZ CKEW) | Once every 2 weeks | Replace any damaged filters | No hotter than 40°C |
From the Daikin user reference guide (4P518786-12K), the Mitsubishi Electric MSZ-LN operating instructions and the Panasonic operating instructions (ACXF55-35210), checked October 2026. Other models differ, so check the manual for yours.
Why every two weeks matters
The mesh filters catch dust before it reaches the coil and fan inside the unit. Mitsubishi Electric's manual says dirty filters cause condensation inside the air conditioner, which helps mould grow, and that clean filters give the best performance and lower power use. Daikin lists what happens when filters are dirty: the unit can't clean or deodorise the air, heating and cooling get weaker, and it causes odour.
The filters work just the same in heating, so keep cleaning them through the winter if you heat your home with the system.
How to clean an air conditioner wall unit's casing and louvres
Wipe the casing with a soft cloth. Daikin says to use water or a neutral detergent for stains, and Panasonic suggests a soft damp cloth. Mitsubishi Electric's MSZ-LN front panel stays on the unit, so wipe it with a soft dry cloth and don't soak it.
Treat the louvre, the flap that directs the air, gently. Mitsubishi Electric says not to soak or rinse it. Never pour or spray water onto the unit itself: Daikin and Mitsubishi Electric both warn this can cause an electric shock or fire.
- No petrol, benzene, thinners, polishing powder or insecticide (Daikin)
- No scouring powder, and only pH-neutral soap or detergent (Panasonic)
- No insecticides, flammable sprays, air fresheners or antibacterial sprays on the unit (Mitsubishi Electric)
How to clean an air conditioner outdoor unit safely
The outdoor unit needs less from you than the indoor one. Most of it is about keeping air moving around it.
- Clear leaves and debris from around the unit, as Panasonic's manual asks
- Check the end of the drain pipe isn't blocked, crushed or buried
- Keep plants, bins, bikes and furniture away, so the air inlet and outlet aren't blocked
- Brush loose leaves off the top of the casing by hand, with the power off
- Don't hose it or jet-wash it. It's full of electrics
- Don't touch the thin metal fins. Daikin warns they're sharp, and they bend easily
- Don't stand on it or rest anything on it
- Leave the pipes, valves and covers alone. They hold the refrigerant
What not to do
The filters are yours to clean. Everything behind them is an engineer's job, and the manufacturers say so plainly.
- Don't take covers off to reach the coil, fan or drain tray. Daikin says end users must never clean inside parts themselves; that's work for a qualified service person
- Don't spray coil cleaners, foams, bleach or disinfectant into the unit. Daikin warns the wrong detergent can damage plastic parts, cause leaks, and make motors fail, smoke or ignite
- Don't use water hotter than the manual allows, or the filters and panels can warp
- Don't wring out the extra air-cleaning filters. Daikin says to shake the water off instead
- Never loosen a pipe joint or valve. Under government F gas rules, only people with the right F gas qualifications may work on the refrigerant circuit
Before and after a long break
Before you leave the system off for months, dry out the inside. Daikin suggests running it in fan only mode for several hours; Panasonic suggests heat mode for 2 to 3 hours to stop mould growing. Then switch off the power, clean the filters and take the batteries out of the remote.
When you start using it again, Mitsubishi Electric's manual says to clean the filters first and check nothing is blocking the air inlets and outlets on the indoor and outdoor units.
When a filter clean isn't enough
Clean filters fix a lot, but not everything. These signs mean something deeper needs looking at.
| What you notice | What it can mean | What to do |
|---|---|---|
| A musty or damp smell that comes back | Dirt and moisture on the coil, fan or drain tray | Book a service. Our smells guide covers each kind of smell |
| Water dripping from the indoor unit | A blocked drain, or ice melting off the coil | Switch off and see our leaking water guide |
| Weak cooling or heating with clean filters | A dirty coil, a blocked outdoor unit or low refrigerant | Run the safe checks in our not cooling guide, then book a visit |
| A burning or hot electrical smell | An electrical part overheating | Switch off at the isolator at once and book a repair visit |
A proper clean, once a year
Daikin's manual recommends periodic maintenance by a specialist, and Panasonic's says the coils and fans should be cleaned periodically by an authorised dealer. Our annual service cleans the parts you can't reach and checks the refrigerant circuit.
- from£119inc. VAT
An annual service
Keeps the manufacturer warranty valid
- from£59inc. VAT
Each extra indoor unit
Same visit
Filter cleaning questions
How often should I clean my air conditioner filter?
Every two weeks while you're using the system, according to the Daikin, Mitsubishi Electric and Panasonic manuals. That includes winter if you heat with it. Extra air-cleaning filters have their own timings, usually every 3 to 6 months.
Can I wash air conditioner filters with washing-up liquid?
A little mild, neutral detergent in lukewarm water is fine. Daikin and Mitsubishi Electric both suggest it for dust that won't come off, and Panasonic says pH-neutral soap or detergent only. Keep the water below 40°C and rinse the filters well.
Can I spray cleaner or disinfectant into my air conditioner?
No. Mitsubishi Electric says not to use insecticides, flammable sprays, air fresheners or antibacterial agents on the unit, and Daikin warns the wrong detergent can damage parts and cause leaks. Clean the filters yourself and leave the inside to an engineer.
How do I clean the inside of my air conditioner wall unit?
You don't, beyond the filters. Daikin's manual says inside parts must be cleaned by a qualified service person, and Mitsubishi Electric says to contact your dealer if the inside needs cleaning. An annual service cleans the coil, fan, outlet and drain.
Can I hose down the outdoor unit?
No. It holds electrical parts, and both Daikin and Mitsubishi Electric warn against putting water on the unit. Clear leaves and debris by hand with the power off, and leave the fins and coil to a service.
Do I need new filters?
The mesh filters are washable and reusable. Replace one if it's damaged, as Panasonic's manual says. Some extra filters do wear out: Daikin's deodorising and silver particle filters are replaced every 3 years. Your manual gives the part numbers.