I built a kegerator system for a hackerspace as part of a collaborative project, but I'm running into some trouble.
I started with a side by side fridge. From what I can gather, it's a GE energy efficient model, and it seems the coils are just in the freezer, and air is circulated from the freezer into the refrigerator.
Rather than put shanks through the door, we have a very nice bar that another member built, so I got the idea of using a small blower to force air through vacuum cleaner hose that contains the beverage lines, up through an upside down U shaped tower made out of PVC pipe, and back through an air return to the fridge. I used foam insulation around the vacuum hose. The blower itself lives in the fridge.
Now things work well initially. The beer stays cold, and the taps and lines stay cold. But over the course of a few weeks the back wall of the freezer starts to frost up and then develops an entire layer of ice. Presumably this hurts the air exchange, and the freezer itself gets above freezing while the fridge temp rises to, say, 60F.
I'm not sure what is wrong. When I was doing maintenance, I disconnected the hoses, taped over the outlets out of the fridge, and turned off the blower. The fridge functioned well. Too well, even; I'd previously set the fridge really cold in an effort to compensate for this problem, and it dropped below freezing. So having the air recirculation loop running seems to be causing it. I don't think I have major air leaks. And I hate having to turn the thing off for long periods of time on a regular basis to completely defrost.
Any suggestions are welcome. An article with pictures showing what I did is here.