HomeAll RepliesReply To: 2019 Yukon SLT Graphite Performance Edition. Odd noise? Reply To: 2019 Yukon SLT Graphite Performance Edition. Odd noise? Sponsored February 10, 2020 at 7:15 am #587384 CraignorParticipant I think I figured it out. I think it’s the ALC Automatic Level Control compressor (air shocks) doing a quick check. Sponsored Subscribe to GM Authority For around-the-clock GM news coverage We'll send you one email per day with the latest GM news. It's totally free. First Name Last Name Email Address Subscribe via Email Leave this field empty if you're human: Sponsored