This is a strange one, I have a 1999 Fleetwood Mallard and I sometimes get a weird humming/wining noise coming from the general location of the power inverter. It's located behind a grill so I have to remove the grill to look at it. It sounds like the cooling fan is making noise but, it comes and goes. The other night, it started again and made a racket all night. I was going to take off the cover in the morning but right when I was getting out of bed, the noise stopped and didn't return for the rest of the day. It's done this in the past too. Any one have an idea? I'm going to open it up this weekend to have a look but, any suggestions about things to check would be greatly appreciated. Cheers!