No trouble out of this 2012 kia Rio until today, started the car up this morning to warm up, 15 minutes later open the door and the whole inside of the car smelt like burnt plastic or an electrical smell. Checked engine bay, and underneath the car, no smell outside of the car, checked the cabin filter, its clean. If I switch to cool air, not ac, the smell goes away. As soon as I switch to heat, them smell comes right back. It's not a antifreeze smell, I've had heater core issues with other vehicles, I know what that smells like, this is different. Fan runs quiet, heat works just stinks badly.