Construction site next to the block for a year – is my 2-year-old unit already clogged with dust?
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Pipera, Aviației area, new block, 12,000 BTU LG, 2 years old. Construction next to us for a year, continuous dust. I wash the filters weekly and they are brown. The unit cools less than last year and the outdoor unit is louder. Is it the dust or has the refrigerant dropped?
What is really happening
Construction dust is fine, mineral and abrasive – it partly passes standard filters and sticks to the wet evaporator, where the biofilm cements it; guidance states explicitly that filter efficiency and airborne particle concentration are the main factors deciding how fast the evaporator fouls. Outdoors, the condenser pulls hundreds of cubic metres of air an hour through fine fins; in a year of construction the gaps fill with cement dust, heat transfer drops, condensing pressure rises, the compressor works harder and louder, and cooling capacity drops – exactly your symptoms. Brown filters every week confirm the dust load. We are not saying refrigerant cannot be the cause, but before discussing refrigerant, the coils get washed – cheaper and in most cases it fixes it.
- Particles reach the air intake.
- Some remain on the filters.
- Internal deposits need assessment and appropriate cleaning.
- Filter efficiency and indoor particle concentration are the most important factors determining how fast the evaporator fouls. [Lawrence Berkeley National Laboratory / , 2002]
- Fouling of the outdoor condenser raises pressure drop and condensing pressure, reducing the split unit's capacity and efficiency. [Science and Technology for the Built Env, 2019]
- A typical evaporator fouls enough to double its pressure drop in about 7.5 years, reducing airflow by 5–7% and raising fan power by 1–10%. [Lawrence Berkeley National Laboratory / , 2002]
- The evaporator and condenser coils accumulate dirt over time and should be checked every year and cleaned as necessary (US DOE). [US Department of Energy – Energy Saver, 2024]
What we do on site
- Outdoor first: we protect the electronics, cleaning solution on the condenser, controlled pressure wash from inside out, in place – cement dust comes out as a grey paste.
- Indoor: collection cover, cleaning solution, pressure wash in place of evaporator, roller, pan; sanitising solution.
- We compare the air temperature at the grille before and after – usually a difference of a few degrees is visible.
- If cooling stays weak with clean coils, we tell you the refrigerant circuit needs checking by a specialist – not our job and we do not 'top up'. See current rates on the Prices page.
What you can do yourself
- While the site is active: filters washed every 3–4 days, windows closed on the site side.
- Outdoor unit: a soft brush over the fins, dry, every two weeks, if you can reach it safely.
- 'Fan' before shut-off.
What NOT to do
- Do not accept a 'refrigerant top-up' before the coils are washed – the most commonly sold useless service.
- Do not cover the outdoor unit with film 'against dust' while it runs – it overheats.
- Do not wash the outdoor unit with a car-wash jet.
Prevention
Next to a construction site, sanitising (indoor + outdoor) is annual without question, sometimes every 8 months. Once the site is finished, you return to the normal rhythm.
When to call us
0764 012 943 / WhatsApp, Monday–Saturday 08:00–20:00. Pipera.
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The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.