we have a brand new kitchen, cabinets were installed two weeks ago, and the combo drawer (also brand new) was installed last week. In the same kitchen we also have a brand new side-by-side subzero fridge (42S side-by-side) which I used to compare the noise level of the combo drawer to. The technician didn't say the fan was faulty, he was just trying different things to see if it makes a difference. He said the new fan made it sound a little bit quieter, but not definitively.
I don't know if 700bc normally is a more noisy model than some other SubZero units.
The technician also suggested us sound proof the sides of the fridge or the "alcove" the fridge sits in (the fridge is 24'', the island it is in is 27'', so maybe that creates space for sound to echo back and forth?). I have not tried it. do you know if this could work?