The unit has 2 blower units in it. The fans were starting to make a lot of noise .. whining .. chirping etc... I ordered a new OEM replacement from HnGlo ... was told they are identical and pretty much do look the same from the outside. Only difference is minor changes in mounting bracket and it now has metal fan vs. plastic. When I replaced the "bad" fan with the new one ... and ran it with my remaining old fan... there are some noises... light howl... variable speed etc.... in the fans. Does anyone know if this is a symptom of electrical differences (power draw etc...) of the new fan? Maybe it draws a little more or less voltage causing the noise and inconsistency of the two fans running in unison? Any help is appreciated..... in the mean time .. I placed a couple drops of light oil on the old noisy fan shafts to lube the bushings and it seemed to help immensely... Thanks in advance !!