Have 2 of these 30 amp supplies. Daily users. Awesome deal on ebay … blah blah you know them. There's dust everywhere. Can't avoid it …. although it has been suggested to slide a leg of thin panty hose over the unit to keep dust out …. or rig your own filter. One of mine experienced a dust buildup on the fan blades and it when it reached a critical point it put the fans blades off-balance making the fan suddenly hard-to-start and noisy. Easy fix. The top comes right off and the fan is the only thing attached to the top. Open top and with a small brush, remove all the dust from both sides of the fan blades, then if you have it, blow off the fan with compressed air be sure to get into the little crack-space where the fan blade mounts onto the fan motor. Fan operation right back to normal.