2015 XC60 T6 Plat

[MSCASDORPH]

106K miles and car is in great shape. Driver’s side climate control blows strong air, but only cold. No heat on driver’s side, and passenger side is fine. Have it at the dealership and they did a coolant flush and didn’t find anything so they’re replacing the heater core now (which won’t happen until the end of January). Anyone else have this issue with possible solutions? Thankfully I have extended warranty and heater core replacement is covered (about $3K, 12 hours). Thanks y’all!