A/C Airflow problem
 

Ok guys I have a question for you. 1985 300D

When the A/C is on high and the button for the top vents only is pressed I get A/C full blast out of all 4 vents.

Occassionaly if I turn the A/C on auto it will begin to start blowing out of the floor and the top vents.

If I turn it on low it almost always starts blowing out of the floor and top vents.

It will sometimes correct itself after a few minutes and switch to full top vents.

If I press the floor and top vents I get air to the floor as well as default defrost.

Which of the pods could be the culprit here? Or is it possibly the push button unit?

Thanks guys!

Maybe