The unit smells of cigarettes although nobody has smoked indoors for a year
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Militari, near Lujerului, 2-room flat in a 1985 block. My father-in-law smoked in the living room for years with the AC on (Midea, 12,000 BTU, about 6 years old). He quit a year ago, we repainted, changed the curtains, but when we switch the unit on it is as if he had just lit one. Can that smell be removed or do we need a new unit?
What is really happening
An air conditioner recirculates the room's air several times an hour across cold, wet fins. Smoke particles (tar, nicotine) stick to the wet surface just as they stick to a cold car window. The sticky layer is Velcro for dust and perfect ground for bacteria and mould, and every time the unit starts, the fan roller – the most contaminated component of any split – blows the mixture back into the room. Repainting fixed the walls; the unit stayed behind like a sponge full of smoke.
- Deposits or moisture inside the unit.
- The condensate drainage route.
- Sources within the room, assessed separately.
- The blower (cross-flow fan) is the most fungus-contaminated component of a split unit, more than the filter or the front of the evaporator. [Indoor Air, 2023]
- The 'dirty sock' or musty smell from an air conditioner comes from volatile organic compounds produced by microbial biofilm on the evaporator and blower. [Current Microbiology, 2000]
- Washing with alkaline detergent, brushing and high-pressure rinsing reduces fungi inside the unit by more than 99%. [Indoor Air, 2023]
- EPA principle: mould must be physically removed, not merely 'killed'; biocides are not recommended as routine practice. [US EPA, 2024]
What we do on site
- We inspect and show you the tar – a glossy brown film on the fins, visible with a torch.
- Collection cover under the unit; on 'smoked' units the water runs out yellow-brown rather than black, the sign of tar.
- Alkaline cleaning solution with a longer contact time than usual to dissolve the tar; repeated if needed.
- Pressure wash in place: evaporator front and back, roller, pan, inside of the louvre housing.
- Sanitising solution over everything we washed.
- Outdoor unit on the block facade, washed in place, so the unit cools without straining.
- Drying, reassembly, smell test with you present. See current rates on the Prices page.
What you can do yourself
- Wash the filters in warm water and dish soap – on smoked units they turn yellow, that is normal.
- Wipe the housing and louvres with a cloth and soapy water.
- Air the room well and run the unit on 'Fan' for 30 minutes after sanitising, in the first days.
What NOT to do
- Do not use thinner, petrol or methylated spirit on the fins to remove tar – manufacturers explicitly prohibit solvents on the indoor unit.
- Do not put an 'ozone' spray or fragrance bomb into the unit – it masks, it does not clean.
- Do not buy a new unit for a smell that washes off.
Prevention
After cleaning, the unit has nowhere to pick up smoke smell from if nobody smokes anymore. Annual sanitising, filters every two weeks.
When to call us
Book at 0764 012 943, Monday–Saturday 08:00–20:00; tell us it is a 'smoked' unit so we allow enough time.
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Read also
- Bad smell from the air conditioner
- The air we breathe at home
- Symptoms of an uncleaned air conditioner
Sources (9)
- onlinelibrary.wiley.com/doi/10.1155/2023/8984619
- link.springer.com/article/10.1007/s002840010120
- link.springer.com/article/10.1007/s002849900435
- pmc.ncbi.nlm.nih.gov/articles/PMC6968652/
- www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-3
- www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
- www.manualslib.com/manual/3613226/Mitsubishi-Electric-Msz-Ln18vg2w.html?page=7
- www.manualslib.com/manual/1236787/Panasonic-Cs-Vu12skq.html?page=13
- www.daikin-ce.com/content/dam/document-library/operation-manuals/ac/split/ftxf-d/FTXF-D_Op
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.