Heat mode is stock on dash vents; no air flow to windshield defrost or feet
I had my car serviced yesterday in a heated garage (it's currently -20-something here),
and a few hours later later discovered the heat mode is stuck on the dash vents; good
hot air flow there, but won't switch air flow when dialed to alternate modes. The service
included changing the cabin air filter, replacing the water coolant pump, and a lower
transmission coolant line (due to leaks), and the right front wheel bearing/hub
assembly. The car was then parked outdoors for several hours in the cold. The garage
is closed for the holidays. What can I check?