They can put in what they call a A/C bomb that is set off inside of the intake of the HVAC system, it is pulled though the vents etc to clear out any musty smells from the A/C system.
Customer complaint is usually “Strange musty smell while using the A/C” of course.
The burning ? scorching smell can be sometimes smelt, when the cabin heater has not been used for a while.
When heat is demanded, after a couple of minutes you get this strange burning smell that quickly disappears after a couple of minutes of use.
This will diminish slowly as the heater receives more use.
It was the same on the Gen1 version we had, but after a good while, it stopped producing this strange burning smell.