W126

Re '82 300SD. Climate control switches blow air at normal rate (auto and full-on), but it only warms up at idle (e.g. stopped at traffice light). Otherwise it is cool but not cold. I replaced the thermostat; engine warms up quickly to operating temp. When fan turned off (not on auto or full on), I can feel nice warm air at side vents, so warm air seems to be in the hoses. But press the buttons and it's only cool air. Is this a monovalve issue? Something else? Thanks.

I R&R'd a new sunroof (Tilting)Weatherstrip.
Pretty much straight forward.......except
1: Found 2 rivets loose on back hold down bracket.
short of removing panels(trying to avoid)
any tricks to fixing? I tried a pair of needle nose vice grips, no go
2:The new strip prevents the roof from closing like the old one!
Should I "grease" it with something? If so what?
Thanks