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First start-up of the summer – what do I do before pressing the button?

Editorial guide · Updated 18 September 2026

In short Short answer: 5 minutes of checking beforehand – filters washed, a torch look at the roller and into the pan, the outdoor unit clear of leaves and objects, then start on 'Fan' for 15 minutes with the window open and only then 'Cool'. If the roller looks black under the torch or 'Fan' brings a mouldy smell, that is not a start-up, it is a sanitising signal – book it before the heatwave, not during.

This page explains a situation in an editorial format. It is not an open discussion board or a verified customer review. Contact us on WhatsApp about your own appliance.

Situation discussed

Aviației, flat, 9,000 BTU Samsung in the bedroom, 4 years old, off since September. A heatwave is coming next week. Is there a 'start-up procedure' after winter, or do I just press the remote?

Editorial explanation · Revizie AC

What is really happening

The first start-up after 8 months is the moment of highest spore concentration: everything that dried on the evaporator and roller over winter is blown into the room in the first minutes, and studies on contaminated units show jumps from under a thousand to tens of thousands of CFU/m³ at start-up. 'Fan' with the window open dilutes the burst; it does not remove it. Dry dust on the roller is also the cause of 'new' noises at first start-up. The outdoor check prevents another early-season classic: the fan blocked by a nest or a wind-blown bag.

Explanatory diagramBefore-season preparation
Before-season preparation
  1. Read the manual and check accessible filters.
  2. Watch for leaks, unusual odours and noises.
  3. Request inspection if something is abnormal.
What the studies say
  • When a contaminated air conditioner starts, airborne fungal concentration in the room can jump from 40–920 to 5,500–100,000 CFU/m³. [Indoor Air, 2023]
  • Spores deposited in air systems resuspend when the fan starts, which is why cleaning must remove them, not just inactivate them. [Science of The Total Environment, 2019]
  • EPA advises not to run an HVAC system you know or suspect is mould-contaminated, because it spreads mould throughout the home. [US EPA, 2024]
  • Daikin, Mitsubishi Electric, LG and Panasonic recommend cleaning the indoor unit's dust filters every 2 weeks. [Daikin, 2023]

What we do on site

  1. If your 5-minute test fails (black roller, smell, sludge in the pan): full sanitising before the heatwave – sealed double cover, alkaline detergent, adjustable pressure wash of evaporator, roller, pan and hose; sanitising; filters; outdoor unit in place.
  2. Start-up test together, on 'Fan' then 'Cool': no smell, water at the drain, normal noise.
  3. See current rates on the Prices page.

What you can do yourself

  • Filters washed and dried.
  • Torch through the bottom grille: grey roller = ok, black = sanitising.
  • Outdoor: leaves, bags, nests removed; 50 cm clearance.
  • 'Fan' 15 minutes with the window open, then 'Cool' at 25 °C.

What NOT to do

  • Do not start straight on 'Cool' at 18 °C with the window closed and a child in the room.
  • Do not use a 'seasonal' spray in the grille – it replaces nothing.

Prevention

5-minute test at every season start; annual sanitising, ideally before this moment.

When to call us

0764 012 943, WhatsApp, Monday–Saturday 08:00–20:00; Aviației is close.

Clean air conditioner with the louver open, in natural light
Clean air conditioner with the louver open, in natural light
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Sources (8)

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.