Same problem on my 2017 Civic LX coupe (Canada). When the a/c runs, it sounds like a dozen starlings in a tree, but muted. Took it in for initial diagnosis today.
Dealer response on report was, "Noise when a/c is on confirmed customer complaint. Noise is from low refrigerant in system. Suspect leaking condenser. Ask customer to return for a/c diagnosis and leak testing for a/c system."
I'll let them run the diagnosis and update with the results.
Invoice from repair reads:
Vehicle needs follow-up a/c diagnosis and leak testing for a/c system, as per previous invoice. Customer reports there is a chirping noise at stationary and also when driving
a/c noise. Connected a/c machine and confirmed refrigerant level is low. Visually inspected all a/c components and found condenser to have signs of leaks. Confirmed condenser is leaking. Replaced a/c condenser. Installed new o-rings. Performed leak test and passed. System can hold vacuum. Charged system and added oil. Turned a/c on and noise is gone.
My repair was completed under warranty.
If you hear that chirping, it's a good indicator that your refrigerant may be leaking out, and given the reported problems with condensers in these cars, that's a good place to start looking for leaks.