Q: 2012 Chevy traverse rear cabin hvac fan continues to run when the vehicle is turned off. How can I fix this?

If there is a relay in the circuit, it is possible the relay contacts are stuck closed. The switch could be stuck, too. Inasmuch as micro- and PC-board mounted relays are used, really the thing to do is use the factory wiring diagram to trace the circuit. Using a voltmeter, and that diagram, you will definitely find out why and where the circuit is powered when you have it commanded the circuit off. If you desire that the required diagnostic steps be performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an electrical circuit/component diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.