dusty heat air when heating on

[Lukeydb]

Hello everyone
I have noticed in my w203 c180k on auto switched off and aircon off dusty air from vents when heating is on, when higher temp.
What that can be how to clean it?
Anyone know?

 

[Tinkerer]

Firstly I would check the air con filter(s) as it sounds like these my have failed or been removed. If they have then you will probably need a good vacuum cleaner to clean out the ducts before renewing the filter(s). The filter(s) could be located in a variety of places and I am not familiar with your car, mine is above the passenger footwell and there can also be some behind the glove box, I have also recently seen one on a C class under the bonnet. Good luck