AC/Heater control knob stays lit up even when not in use

Hello, if the headlights are off and the key is off and you leave the vehicle, this light should not stay on. However, I cannot be sure of any of those things by your question. If the light stays on, there is likely a concern with the climate control head internally, or perhaps a short to power causing power where it should not be when the system and vehicle is off. Hands on testing is needed to figure out what is going on. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops