This photo shows the "raw" interior of the compartment from above - the furnace is shown along with wires, pipes and etc.
If you look close on the right side of furnace you will see the looping LP copper pipes that I had to take loose and cut them down a couple inches, then re-flange them and put back in place. The hardest part of that was the effort needed to seat (seal) those flanged ends to the manifold so that there was absolutely NO leaks or seepage of any kind - had to torque them down rather hard (around 100 ft pounds).
The support in front of the furnace was removed entirely so that I could cut it down also - had to take off around 2 inches and then reattach it. The floor of the compartment had to be lowered about 2 inches, and I supported it by braces down to the floor below the furnace. Had to carve out an opening so that the floor actually kind of surrounded the furnace and I installed a very thin sheet metal in the cut-out directly above the furnace - in order to maintain the height that I needed. Measuring the opening I discovered the Frigidaire would roll right in over the wood flooring and skim just above the sheet metal - no pressure on the sheet metal.
I used caulking then to seal all around the wood compartment flooring, and sealed the sheet metal also to stop any and all air intrusion.
The roof vent was taken out and I put in a bottom to contain the foam until it set up. The roof vent is now totally sealer so no air, hot or cold, comes in through that opening.
The outside vent (old one for access to Norcold) was removed and I sealed that up also with foam.
The Frigidaire does not draw "any" air from outside the coach for anything. If someone asks, how does it cool and breathe? The answer is ---- the Frigidaire pulls air from the top - above the fridge, down the rear of the unit - then across the fins, and then blows that warm air out through the bottom into the living space - this warm air passes just above the shallow "drip" pan under the fridge - and serves to evaporate what little drippings may be there in the frost free unit.
So - do not have to worry about cold air drawn in, or hot air drawn in through the roof vent or access vent outside the fridge.
Here is that photo::::
Furnace from top picture by sepisllib - Photobucket
God Bless
Bill