W202 - Air Vents stop working unless you bang on dash board on the passenger side

[trueog]

Hey guys I have a strange problem. My air vents stop working sometimes. I'll even put it on max and nothing comes out of my vents and the fans don't even turn on.

Then if i bang on my dashboard on the passenger side or from under the dashboard on the passenger side, everything starts working again. I've checked the cabin filter and its fine not even packed with dirt either.

Anyone know what might be causing this to happen or which part might be on its way out?

let me know, thanks