My Printrbot was an earlier model that shipped with the Ubis 13 (a.k.a. Ubis Ceramic) hot end. The Ubis 13S is a compatible but improved version that is still available.
This hot end requires fan cooling for the heatsink around the top part (cold end) of the component, but the Printrboard Rev. F5 that I have only supports a single fan which is already in use to cool the extruded filament. (If you're lucky enough to have the F6 Revision of the Printrboard it does have built in support for a second fan.) There are a couple of workarounds for adding a fan to the F5 board.
Option 1 - Wire a fan directly into the power connector. In this configuration the fan will always be on when power is applied to the Printrbot. Since I leave mine powered all the time this isn't a great solution for me.
Option 2 - Splice the second fan into the existing fan leads. I believe Printrbot used to offer an upgrade kit that did exactly this. Still not a great solution though since the new fan will mirror the behavior of the existing fan, and that's not really what I want either.
Hot End Auto Cooling Fan for Rev. F5 Printrboard
You can follow Aistaca's original instructions here but here are a few guidelines. I'm also including my Digi-Key BOM for the parts I used.
Print the fan mount for the Ubis 13S which can be found here. There are two versions, print the one without the extra bracket on the bottom. Printrbot used to sell a LED kit that would attach here but it's no longer available.
Wire the fan according to Aistaca's diagram (the last image at the Thingiverse link). I installed a connector near the fan to make replacements easier, and also the 1x1 housing so that I could attach to the Printrboard EXT1 PIN3 without having to solder directly to it.
The last step is to make the appropriate changes to your Marlin Configuration_adv.h file and rebuild. (If you need help building Marlin FW, see my blog post here.)