Tom Wiltrout

2020 gmc denali HD has heat but right vent on drivers side blows cold. Tried cycling the system through all its functions with no change. Just the 1 vent will not blow heat the dealer said the actuator doors are working and want to remove the dash to replace the heater core. All the other vents blow heat just not the right drivers side so I thought it was unusual to replace the heater core. Any insight is appreciated