I am not totally sure your 86 Sunline had a fan in the power converter being that old. BUT, someone may have upgraded it along the way. The power converter creates 12 VDC power when you are plugged into 120 VAC shore power. The power converter charges the battery on the trailer A frame by the LP tanks an creates 12 VDC to run lights and other things inside the camper, that run on 12 DC.
To find the power converter and the circuit breakers, find the outside shore line cord that you plug into the house or a campground power post. Where the shore line cord enters the camper, many times, the power converter and circuit breakers are just inside the camper to keep the power cord short. And many times it is burred inside a lower cabinet or a nook of sorts under a cabinet. There would be a removable wood panel or door of sorts.
If someone upgraded the original power converter, yes, they can have fans and they can drive one nuts in the middle of the night when they run. This is a common issue on some of the older power converters. If that is the fan you are hearing, there is no switch to shut it off as it has to run to cool down the power converter. You can shut the power off to the converter and that will stop the fans, just you will loose power also. Most times when the fans act up on a power converter, if that is what is making the noise, then they need to be replaced or the many times, the entire power converter as the older ones where really not good battery chargers, more like battery killers overcharging the battery.
Once you find the power converter, if that is the problem, post the make and model and ideally a few pictures of what you have so we can help better. Pictures in this case really help as on a camper that old if some one changed something, it is hard to tell what your have. If you need help on uploading pics., let us know.
Hope this helps
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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