I would bet that the engineers did design it originally to bring in cool air from below and vent it out the top. What sometimes happens is that the incorrect fan is substituted because of inventory shortages or price difference to which the bean counters always adhere to. I would advise against changing the electrical polarity of the fan, but rather to physically rotate the fan and remount it so that it vents out from the top. These small fans usually contain some components on a PCB that are used to current regulate or sense RPM's, and that is the reason why I would not rewire it. 73 OM
I would bet that the engineers did design it originally to bring in cool air from below and vent it out the top. What sometimes happens is that the incorrect fan is substituted because of inventory shortages or price difference to which the bean counters always adhere to. I would advise against changing the electrical polarity of the fan, but rather to physically rotate the fan and remount it so that it vents out from the top. These small fans usually contain some components on a PCB that are used to current regulate or sense RPM's, and that is the reason why I would not rewire it. 73 OM
I needed a Tuje fix! 73, KF4LMZ
Where did the ceramic fuse come from?