Just bought the car two weeks ago. Everything seems to work okay but when I turn the ignition on before I start it, I hear this crunching, like 10 mice are chewing inside the wall type of noise. It also sounds kind of like a modem sound but more mechanical. I was told from a friend that it sounds like a relay going bad. It’s not loud and I can’t really hear it where the engine running. but when sitting silent with the ignition on it’s pretty obvious.
Could be the fuel pump priming when you turn the ignition on.
Under the dashboard?
Bad blend door actuator seems most likely to me. Feel around under the dash with the under panels off. You should be able to feel the crunching.