Converter/ Furnace Issue

[CPCole]

I have a 2013 Starcraft Autumn Ridge 336 RESA TT. My issue is that if I have my furnace and my converter running at the same time when connect to shore power or my generator the furnace or the converter makes a grinding sound like there is something caught in the blades. While the furnace is running just on battery it is fine. If it is running and I flip the breaker to turn the converter on the noise comes back. I then shut off the heat and the noise goes away.

So the bottom line is that when both are running it is very loud grinding type noise and if one or the other is turned off it is quiet. Anyone ever come across this wired issue? Thanks in advance.