How often should I wash my AC filters?

Every month during heavy-use periods. Wash with lukewarm water and neutral dish soap, air-dry in the shade.

What is a chemical coil clean and how much does it cost?

It involves spraying the heat exchanger with an antifungal chemical that foams and removes mould and grime. It costs €40-80 and is done once a year.

Filter & Coil Cleaning in AC / Fan Coils: How to Save on Electricity and Allergies

You may own the best heat pump in the world. But if your AC units or fan coils are "clogged", the house will never heat up - and you will be breathing a toxic cocktail of dust and mould.

How cleaning cuts your electricity bill and what exactly the technician must do inside the indoor unit every year.

1. The "Clogging" Effect and Your Electricity Bill

An AC unit or fan coil draws in room air, passes it through a frozen (or heated) "radiator" and pushes it back out. Along the way, it simultaneously sucks in dust, pet hair, smoke and moisture. If you don't clean it, the machine will "suffocate".

When filters fill with a thick layer of dust, air cannot pass through the unit. You reach for the remote and set it to 18 °C or push the fan to maximum, but nothing changes.

Dirty AC filters – dust build-up, clogging, increased electricity consumption

📉 Reduced output

The unit barely moves any air. The room never reaches the desired temperature. Fan on maximum, noise through the roof - comfort at zero.

⚡ +30% electricity

Because the room never reaches the desired temperature, the outdoor unit (the compressor) runs non-stop at 100%. A dirty AC can consume up to 30% more electricity compared to a clean one - tens of euros per month wasted for no reason.

🩺 Allergies & health

Dust, pet hair, smoke, humidity - everything passes through the unit. Without cleaning, you breathe whatever sticks to the filters. Ideal for triggering allergies and asthma.

🔧 DIY every month

Open the front plastic cover → remove the mesh screens (the basic dust filters) → wash with lukewarm water + a little neutral dish soap. If you have extra activated-carbon or ioniser filters (small coloured sponge inserts), remove those too - they are not washed but replaced annually.

Drying secret: Let filters air-dry in a shaded area. Never in sunlight or with a hairdryer - the plastic is sensitive and will warp, meaning they won't clip back into the unit properly.

2. The Coil (Heat Exchanger): A Professional's Job

Chemical coil cleaning in AC unit – aluminium fins, antifungal spray

Behind the filters sits a silver metallic component with hundreds of thin aluminium "blades" - the coil (heat exchanger). This is where the real heat transfer happens.

🦠 Why it gets dirty

No matter how good your filters are, micro-particles stick to the wet aluminium (condensate). Mould, bacteria, a "wet sock" smell - a sign the coil has developed fungal growth.

🧴 Chemical spray

The technician sprays the coil with a specialised non-toxic, antifungal chemical cleaner. The liquid foams up, "eats" the mould and grime between the aluminium fins, then rinses off with a little water - straight down the condensate drain. The process takes 15-20 minutes and once a year is enough.

📊 Result

After cleaning, cooling/heating capacity returns to 100%. The compressor stops straining, consumption drops and the temperature response is noticeably faster.

💶 Cost

Chemical indoor-unit clean: €40-80. Deep clean (with blower removal): €80-150. Against the electricity savings, payback takes 2-3 months.

3. The Blower Wheel: The Hidden Mould Distributor

At the bottom of the indoor unit hides a cylindrical fan - the blower wheel. It is the most neglected component, because it is invisible without disassembly.

🖤 Black mould

Because the blower is permanently wet in summer, it collects a thick black layer of mould and compacted dust. The unit starts leaving "black specks" (like pepper) on the wall and furniture.

📳 Noise & vibration

Due to the weight of the grime, the blower loses balance. It starts vibrating and making noise - a rattling or thumping sound. Many think something is broken, when it just needs cleaning.

🚿 Deep cleaning

The technician removes the plastic covers, disconnects the blower, takes it to the balcony or bathroom and washes it with a pressure washer + chemicals . A simple brush is not enough.

⏰ When needed

Once a year, ideally before the cooling season starts (May). In homes with pets or smokers, a second round may be needed (October before heating).

4. Summary: What, When, Who

The air quality in your home depends entirely on the cleanliness of these machines. Do not wait for summer to remember them.

AC cleaning summary – filters, coil, blower, maintenance schedule

🏠 Filters (DIY)

Every month during heavy use. Wash with lukewarm water + soap. Air-dry in the shade. Replace activated-carbon filters every year. Cost: €0.

🔧 Coil (Technician)

Once a year. Antifungal chemical spray + rinse. Cost: €40-80. Result: +30% better performance, zero odours.

🚿 Blower (Technician)

Once a year. Disassembly, pressure wash + chemicals. Cost: €80-150. Result: zero "black specks", no noise.

💰 ROI

Annual full-service cost: €120-230. Electricity savings: 20-30% per year. For a home with 2 splits: €80-200/year saved. Payback in 6-12 months.

🔑 Wash your filters regularly. Demand a chemical coil clean + deep blower clean. The maintenance cost pays back many times over through lower electricity bills.

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