Does the noise happen when you are hook up to shore power or on battery supply. I'm asking because it could be actually your converter fan that comes on every so often when furnace is running and your are on shore power. When you hear noise again and you are on shore power, remove shore power and run on battery for a while and see if noise goes away.
2011 Rockwood 8319SS with ProPride 3P hitch/GoodYear Marathons/TST TPMS 507
2008 F250 Lariat CC SB 6.8L V10 4.10 axle ratio (NITTO TERRA GRAPLER G2 LT275/65R20E)
Yamaha 3000iseb generator:Progressive Ind. EMS-HW30C : Eastern Ontario
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