M4300-24X24F Missing rear fan?

Do both fans on the rear of the M430024X24F switches always run or do they stop if

the ambient temperature is above a certain degree?

I have 2 brand new switches out the box that only the right side fans are spinning, if looking from the rear. The left fan doesn't seem to be spinning and the top switch doesn't even have a fan installed! Are they only shipping now with one fan or did the QA guys fail that day?