I have had a whistle in my 2015 Canyon since new. I went through the attempts to resolve it by various attempts to repair the cabin air filter door.
I found the whistle to be audible under the hood when the AC is running. Anyone hearing the whistle, lift the hood and see if you can hear it even louder while the engine is idling and the AC is cycling.
In March, 2016, my dealer did investigate further for the whistle under the hood. From the details of the service invoice, they determined by using a microphone that the noise is very loud by placing the microphone on the AC line just behind the resonator. I do not know exactly where that is, but it was confirmed by working with a field service engineer and GM engineering.
Further, they found the noise present on two other trucks in dealer inventory. A few months later when I was in for one of the recalls, the service manager stated all 2015 and 2016 Colorado and Canyon trucks make the noise. Some whistle all of the time, others intermittently like mine. Some do it when new, others after a few thousand miles. They do not seem to be making progress fixing this irritating whistle because engineering is busy with safety related issues.
I did engage Customer Service after posting on this Forum. They seemed interested in helping me initially, but after a few weeks, they responded that they communicated with my dealer, and are turning the issue back to the dealer. I expected Customer Service would be able to communicate internally with additional information to help my dealer, but instead, they only reached out to the dealer and did not provide any additional information or support for me.
I will not provide my case number or dealer name on this Forum, but if Customer Service is actually willing to help get resolution for this irritating issue I will gladly provide that information. If the only assistance Customer Service can provide is to contact the dealer, then don't waste my time and raise my expectations falsely.
2015 GMC Canyon SLT 4x4, Onyx Black, Fold-a-Cover