Just like everything else on our car , AC fans and blower also need time to time cleaning for best air flow , so how we know that out car ac blower or fan is dirty and needs cleaning ? all of this work can be done at home with some basic hand tools
there are some very classic signals by which you can be sure
1. car ac blower making more noise as compared to airflow
2. dashboard vibration while ac is on
3. not enough cooling from ac

if you have anyone of these problems then chances are that you car too needs a blower fan cleaning

performed on a volkswagen polo , process identical on vento , jetta , passat , skoda fabia , skoda rapid , golf , octavia , superb , some models of audi like a3, a4 , a6
process similar on every car , majorly 99% of all the cars.