Plastic burning smell

Hi I have a 2002 Mazda MPV and recently have had a plastic burning smell coming out of the vents and noted in the drivers side front of car near the engine compartment. The underbody of my car was looked at at an oil change place, and no bag was found hanging off of any hot engine part. The only suggestion that was given to me was that the blower motor for my heat/ac was going. Not sure and could use help. Thanks to anyone out there with a similar issue.