Product review (1 stars): it is a great exhaust fan for 2.5years...
After 2 years of use, it is a great exhaust fan. Powerful almost quiet. But on the 3rd year a high pitch sound starts to develop, it's gotten progressively worse, until today the sound resembles a motor under stress and you can hear it slow down and eventually stop, I shut it off right away to prevent burning the motor up.  My guess is the motor bearing is blown.  I will call customer services to see if they have a replacement motor.  I have never had an exhaust fan fail that way and in only 2 years...

Warranty is 1 year. Replacement motor cost $138 plus taxes and shipping handling.