If a rotor is chirping then it should be getting hot. You don’t need to stick your head out the window to find out which rotor is chirping, just pull over, lick your finger, and lightly (and quickly) touch the rotors until you find the hot one.
O.K. I’ll bite.
What are you talking about? Both of the rotors can be hot from normal brake application. The chirping you hear could be the wear indicator on the brake pad. Instead of doing something foolish like sticking your finger on a hot rotor, why don’t you just remove the front wheels and inspect the brakes.