What is missing here?

[928 Bro]

Sorry about the bad pic that gives you very little idea or point of reference. Wish I would of taken it when the hood was off the car. This hole is on top and the bottom of my air duct right after the rubber boot goes that connects the blower for the a/c, on my 1980 928. Is there a sensor or lever that might be missing? thx

[AirtekHVAC]

I THINK... A rubber plug goes there... It is access to the screw at the bottom. If I can remember, I will go look at mine this evening and get back to ya

[928 Bro]

thx