<VV> Squealing noise from engine compartment

[Joe White]

Hi All, 

I have a squealing noise coming from my engine compartment. The noise is worse when I have my headlights on at night. At idle I cannot hear a squealing noise, but the alternator light is on. As I rev the engine the noise starts and progresses until about 2500 rpms then the squealing stops and the alternator light turns off. At about 4500 rpm at the squealing starts again and the alternator light turns on. Between 2500 rpm and 4500 rpm, no squealing, no alternator light. When I drive the car during the day, no squealing, no alternator light.

I suspect that the alternator is going bad, but wanted to post this on VV to see if anyone had other thoughts.

Regards,
Joe White
Boulder, CO
CORSA, RMC