I'm a bit perplexed by a squeaking/chirping noise that's coming from the vents when I run the heat and air. I took out the motor and fan to check for debris. When I remove the 3 screws, drop the fan and then run it, I'm not hearing the squeak. The air cabin filter is brand new. It makes me wonder if it's something in the fresh air return area? Anyone ever taken the time to clean that out? I can't find a video on how to access it. I'm assuming it's behind the windshield cowl?