Most abnormally loud fan noise is due to faulty installs---which comes under your installer's warranty, not the manufacturers. Your installer should have been there when the service rep came so they could put their heads together. Fixing the problem is his issue. If you can't get him back out to diagnose, then you may have to pay for another HVAC person to diagnose the issue.

My installer came back and removed the fan from the range hood and it was determined that the fan cage is warped so the fan doesn't spin true, thus the abnormally loud noise. This time it is the manufacturer's responsibility to honor the warranty.

live_wire_oak, I want to thank you for taking the time to respond to my problem. You helped me to get the process started and hopefully get this problem fixed.