Autumn and winter in Wrocław are not only beautiful architecture, but also constant humidity. You get into the car, start the engine, and a moment later the windows turn “milky”. Sound familiar?
Many drivers resort to a cloth, wiping the glass while driving (which is dangerous), or open the windows, letting the cold in. Fogged windows, however, are not only a matter of physics — they are a clear signal that your car’s ventilation system is not working correctly.
SerwisUA experts analysed the main causes of “fog” in the cabin and prepared effective advice on how to restore perfect visibility.
The physics of the process: where does the water come from?
The cause of fogging is simple: a temperature difference and high humidity. Warm air from your breath and the heated engine hits the cold glass and turns into condensate (condensed water).
But why are the windows clean in one car, while in another water literally runs down the glass? It is about how effectively the car can remove that moisture.
Cause no. 1. A “tired” cabin filter
This is the most common cause, which we diagnose in 8 out of 10 cases at our workshop.
The cabin (pollen) filter works like the car’s lungs. It traps dust, soot, fungal spores and allergens. Over time it clogs with dirt and, worst of all, holds moisture.
- How it works: when you switch on the blower, air passes through a wet, dirty filter and enters the cabin already humid. Instead of drying the windows, the heater only makes things worse.
- Solution: replace the filter. In Wrocław, because of high dust levels and smog, we recommend replacing it every 10–15 thousand km or twice a year (before summer and before winter). A filter with activated carbon is the best choice, because it also neutralises unpleasant smells.
Cause no. 2. The myth about air conditioning in winter
“Why switch on the air conditioning if I need heat?” — customers ask us.
That is a basic mistake. Air conditioning (climatronic/AC) in a car has two functions:
- It cools the air.
- It dries the air.
In winter the A/C button should be on! The system works so that excess moisture condenses on the evaporator and is drained under the car. That is the fastest way to remove “fog” from the glass.
- If that does not help: if A/C is on and the windows still fog — there is probably too little refrigerant in the system or the compressor is faulty. Drop in at SerwisUA; we will check the pressure in the system.
Cause no. 3. Moisture under your feet
Look at your mats. If in winter you use textile (velour) mats — you are carrying a “pool” with you. Snow from shoes melts, water soaks into the material and does not dry for months. After the cabin warms up, that water evaporates and settles on the windows.
- Expert tip: for the winter season in Poland, be sure to switch textiles for rubber mats (trays) with a high rim. Water from them is easy to pour out.
- Body tightness: sometimes water enters the cabin through clogged drain channels on the scuttle (where the wipers are). Leaves block the drains and rainwater runs straight under the floor covering. That is dangerous, because electrical looms run there.
The invisible enemy: fungus and bacteria
If the cabin is constantly damp, and after switching on the blower a smell of “old socks” or mustiness appears — fungus has settled in the ventilation system. Breathing such air is dangerous to health, especially for children and allergy sufferers.
In that case a simple filter change is not enough. Interior ozonation is needed. Ozone kills 99% of bacteria, mould and viruses in the deepest corners of the ventilation system and upholstery.
A comprehensive solution from SerwisUA in Wrocław
Do not struggle with a cloth and do not risk safety because of poor visibility. Preparing the air-conditioning system for winter takes less than an hour.
What we offer:
- Express diagnostics: we will check the filter condition and the operation of the recirculation flaps (sometimes the cause is a stuck closed-loop flap that “recycles” the same air).
- Cabin filter replacement: we will match a high-quality equivalent (Bosch, Mann, Filtron) to your car.
- Ozonation: full interior disinfection with a professional ozone generator.
Promotion until the end of the month!
With an oil and filter change — a check of brake fluid and coolant condition free of charge.
We speak your language and we understand your car.