Converter fan always on after replacing circuit breaker

[Turbo]

I recently lost the 12V power in my trailer and noticed the "short stop" circuit breaker mounted near my battery looked pretty corroded. When I tried to clean up the connections the plastic mounting tabs crumbled, so I replaced it with a new one and everything worked again. I did take notice that the original short stop was labelled 12V 50Amp, so I replaced it with the same one despite my trailer having a 30amp system.

Since then, I've noticed that my converter fan is running constantly when connected to shore power and definitely did not prior to this. I only have two non-led bulbs that when on would trigger the fan, now the fan runs when everything is off. The battery is a year old and reads 12.9V when disconnected. The Converter is a WFCO.

The shortstop has two connections, one labelled BAT and the other AUX. I fed the wire from the battery to BAT and from AUX to the coach. Is it possible I screwed something up?

I've tried searching, I've vacuumed the the converter which was suggested. Any other suggestions or is this converter on the way out?

Thanks!

[Grumpy]

The converter fan runs when it is charging the battery or under a load. Your battery may not have been charging correctly due to the corrosion and now it is.