We have a 2014 Southwind and had the same problem last year.
After checking "all" fuse boxes several times and nothing, I finally called a mobile service tech to look at it.
He found a 25 amp in-line fuse high up in the dash behind the speedometer that controls both the Power Gear Levelling system and the chassis heater blower motor.
This fuse did not show on any schematics.
If your RV has the access panel on the top of the dash, open it and the fuse is there.
2014 Fleetwood Southwind 32VS 🇨🇦