I have a 3 way also and I have build duct work over my coils with two 12 volt fans. The duct work has insulation on the outside and will have the ducting vented to the outside, and I have not decide if the input air should be cabin or outside. I'll have to play with that. The exhaust will be insulated and of course vented over board. After reading posts of others I plan on an inside fan to move the air around, but I will have a remote thermometer inside, so I make sure I have refrigerator
running right. I also plan on an extra layer of insulation around my Refrigerator
. With all the complains about warm refrigerators I am taking the extra steps to make mine work as good as possible. Could be over kill, but I am leaning on the very safe side.