5 ton unit is making a lot of noise

by Annie
(Boston, MA)

We recently installed a 3 ton Greenspeed for our 1st floor and a 5 ton unit for the 2nd and 3rd floors of our house. The 3 ton unit is very quiet. I never notice when it comes on. The 5-ton unit, however, is making a very loud noise with some high pitch in it, too. I'm hearing it through the windows and it sounds kind of like an airplane is flying overhead. I am going to ask the installer about it-- it's his first time installing a Greenspeed-- I am hoping there is something that can be adjusted...