Honking sound in 2008 Honda Pilot when AC is on

Maintenance/Repairs
1

My wife’ s Honda Pilot makes a mysterious squeaking or “honking” sound (this is the term the Honda service team used). It happens at random, whether the car is cruising on the highway or stopped in the driveway and lasts only a second. It only seems to happen when the air conditioner is on. Honda has tried a few things to ensure valves are sealing etc. but still no luck. One of the service techs had heard of this happening but had no solution. It doesn’t impact drivability of the vehicle but is incredibly annoying. Can happen once on a 30 minute drive or ten times. We’ll end up selling the vehicle if we can’t find a fix. Any ideas?