No heated air from center vents

[dichronic]

I'll preface by saying I did a lot of searching but didn't find anything quite like this...

My center vents on my '82 SL 280 physically function fine. I can open & close them with no issues (which seems to be the most common issue I've seen on here). The air coming out of the center vents is either at outside temperature or cooler (if desired). When I use the heat, the air coming out of the SIDE & FLOOR vents is heated as desired but the air coming out of the CENTER vents is outside temp (cool / cold). The past couple days, when I've wanted heat, I've had to close the center vents to prevent them from countering the heat coming from the side vents.

Not sure if it matters but I'm pretty sure the AC on this car is not working, though I've never really tried using it since checking the AC while test-driving the car (just purchased a couple weeks ago). Just throwing that out there...

So, any ideas or suggestions would be appreciated. Thanks...

[280EZRider]

The center vents (dash vents) are for fresh air & AC air only.

[dichronic]

well, that would certainly explain the "problem". Thanks!