2012 Buick Verano Ac whine/hum

My car is a 2012 Buick Verano with the 2.4l L4 with 38k miles. Note this ac noise may have been present before and I just recently noticed it because I usually drive with my music on. When I switch the ac on and the compressor turns on there starts a whining/humming noise that changes with the rpm. It’s not super loud but it’s loud enough to be noticed Inside the car and out. I feel as if I’ve narrowed it down to the compressor Considering it’s only present when the ac is on. I took it to my local dealer and they diagnosed it being the cooling fan. This does not make sense to me because the noise changes with rpm and the cooling fan isnt driven by the engine its electric, plus the noise is only there with the ac on. I asked to speak to the technician but they said he was busy and he would call me but it’s been a day and that hasn’t happened. Just wondering if anyone has any tips for dealing with the dealership, as cynical as this sounds I’m suspicious that they are saying the wrong thing that way I pay the 100 dollar deductible for the warranty and then come back with the same problem and pay another 100 for the actual fix. I usually just try to give the benefit of the doubt but for someone who is a technician for a living that diagnosis is rather ridiculous for the described symptoms. I guess I just wanted to rant to haha.