The 802.11ac AirPort Extreme and Time Capsule employs a fan near the top of the unit that draws in air from the bottom. Be sure to check the base to see if there is anything blocking it. To get a better idea on what is going on inside your base station, please take a look at this iFixIt site.
Ok, with that said, what can be done about it. Unfortunately, not much. Disassembling the unit would potentially void any warranty and not necessarily fix anything. The potential issues are either a faulty fan or power supply or both. Of course, I am assuming that you are operating your base station in a relatively cool environment, not near any object that may obstruct the base, or not inside a closed space.