Each time my central A/C turns on, there is a loud buzz for less than a second from the CB panel, then the A/C comes on and runs just fine. The A/C is a new unit, but I recall hearing the buzz with my old unit for many years and thought it was related to that. I have 200A service but the panel was installed in the 70's.
I had the cover off and when the A/C turns on I don't see or smell anything.
Any ideas or suggestions would be appreciated.