I also have the WFCO converter on my 2012 Coachmen. After two months it went bad and the dealer replaced it. I wish I would have thought about paying the difference and having them install a Progressive converter. I have been told that even though the WFCO has a smart charging system installed in it, it is not as good as the Progressive when charging the batteries. The WFCO converter's fan will only come on when needed. As stated before, I suspect that the fan came on because the unit was charging the batteries and the few lights you had on.
99 Ford F250 4X4 7.3 diesel, Banks System
Rite airbags w/compressor, exhaust brake
2012 Coachman Chaparrel 32' 5er