HVAC Center & Passenger Vents Won't Blow Hot Air?

All,

Strange new issue. Did a search but didn't see anything on point.

Haven't cranked up the RS6 since it went in for the engine temperature sensor replacement, but did today. Cooler out (in the high 20's to lower 30's). Had HVAC set at 70 for both driver and passenger. Driver side vent blowing hot air, but neither center vents nor passenger vent were blowing hot. Just cool. This past year, I replaced all three of the actuators for the HVAC system. Thoughts? Thanks!

CW