Why would my heater blow only hot air regardless of temp setting? on 2006 Mercedes-Benz S350

AC still works on LO setting

Asked by for the 2006 Mercedes-Benz S350
possibly an air door actuator that is stuck or broken blend door. u have like 6 or 8 in your car.
thank you for your response is this something i could possibly fix myself od is this a trip to the dealer
well 1st you need to determine which ome is bad then depending on location it could be an easy one or a 5hr job. i rec at least spend the $ for a diag then see what they say. these can be difficult to change if its a hard one