I have a 2011 KIA Sportage and I am getting a burning smell ( sort of plastic burning) from the AC vents whenever i accelerate immediately i.e when my rpm crosses above 3500. This lasts for a few mins and then the smell goes away. I had pointed out this in the KIA service center twice and i felt like they have reduced the pickup power, but the same problem is found to be repeating. Does anyone notice this kind of issue and is there any solution?