Your profile along the side does not indicate which year and model you have so we are very limited to how we can respond. It would be great if you could edit your profile to show that information as you see I have to the left of my response.
We have a Tripp-Lite inverter on our 2007 2350 so I will give it a shot.
I do not believe there is any elecrical device above the heat shield you describe. On our year & model, I can get a good look above the heat shield through the right side rear wheel well. I examined the main battery cables that pass through there to get to the inverter to the left of the fridge.
Open the access door to the inverter (originally screwed shut at the factory) and hit the rest button on it when the unit is misbehaving. That might do the trick for you. If not, turn the inverter power switch to each of the 3 settings and back.
If nothing works, there is one more thing to try. Get a small mirror and flashlight and look up from below at the control panel. Reach up there and unplug the connector that resembles a Walkman headphone jack and observe what happens. Do not confuse that connector with the one that resembles a telephone jack. Unplugging the proper connector disables the auto-on-invert feature which places the control panel into a user-control mode. In this mode you may be happier to control when the inverter is generating 110v, and just as important, when it is not to save your battery reserve power. You could kill power to the inverter using the switch by the main entry door, but then you have also killed 12v power required to run your fridge off propane.
Click on the link below to read more about it.http://www.phoenixusarv.com/community/index.php/topic,73.0.html
Ours is also a 2007, I am pretty good with this stuff, I disabled the "auto invert" cause We use our PC alot, Without A land line!
We have it for over 3 years......
I sent an E-mail to PC with a little more Information about the problem, I know we can resolve this,
..I will keep you filled in! This is gonna be an interesting problem.