I have a 2014 Chevy Cruz LS 1.8. With the hood up and looking at the firewall, there is a HVAC duct with a flap covering it a little to the passenger side from the middle and less than a foot from the top. This duct runs at least to the cabin air filter. A mouse entered here (pieces of filter were found under the flap) and made a nest on top of the filter where it then died! I went to the dealer that we purchased the car from and their service dept. tech. manager did not know what it was or it's function. When asked if the flap could be wired shut to keep mice out, he said he saw no problem in doing so. It seems like GM needs to come up with something to prevent this problem.