pmspirito,
Sorry its taken so long to reply to your question. The trailer was in winter storage up until last week. I took some closeup pics to help show the story of the air conditioner.
1. The door has taken the weight of the unit fine. No sign of sag or fatigue. However, not all trailer doors are created equal. If there is a week link in CT doors, I think it would be a light weight hinge. The sheer strength of most door panels is high.
I did NOT take the door apart and put in extra steel (like some have). I slipped 3/4 x 4 pine between the inner and outer panels, surrounding the cut out hole, then glued and screwed them into place. The door was then inserted and screwed to the pine.
2. My door was the perfect fit for my air unit. This was critical when it came to how I "mounted" the unit.
3. The unit it "mounted" using only the force of gravity. Here is how
4. I screwed a 1 1/4 inch aluminum angel iron piece to the top of the unit
5. The unit is lifted into place, with the top slipped in first, so the aluminum piece sits just inside the door frame.
6. The bottom of the unit rests on the bottom of the door frame. Fortunately the bottom of the unit face has a "step" so that, in this position, it abuts the door frame. This keeps the bottom of the unit from moving into the trailer.
7. With the unit in place, the unit's weight is cantilevered off the back of the door. Pressure pushes the top aluminum L bracket against the top of the door frame. Pressure pushes the unit's bottom "step" against the bottom of the door frame. After its in place, I place a strip of foam on each side to seal things up.
Where I travel, if its raining its cold and the unit is either at home or stored under my bed.
Ive had no leakage problems.
Around here, dust is a bigger challenge. With the sides sealed with foam, Ive had no dust get in, even during the WORST of storms.
The door is handling the torque of the mount, showing no signs of deformation, stress or bending.
The only draw back I see is if someone moves often; Lifting the unit in and out is kind of a pain.
While moving the unit around, I duct tape a piece of 1/4 plywood to the back of the unit so as to not dent the cooling fins.
I only mount the unit while camped. I never leave it there while "on the road".
Most of the time I leave the unit at home because its not that hot where Im going. Leaving it in while on the road could be a problem if it experienced a large dynamic load (bump) causing a lot of torque on the door.
I think someone could permanently mount their unit to their back door this way with a couple modifications. Of course you would screw the top and bottom of the unit to the frame around the hole. Then in order to mitigate the torque of dynamic loading, you could add diagonal bracing from the back of the unit to the door. The unit's exterior frame should be robust enough so that you don't have to add a shelf.
Keep in mind the strength of your door comes from its hinges and from the sheer strength of your exterior and interior skins. My door had NO steel vertical studs (like the walls). Instead, the door skins were screwed to horizontal 3/4 x 4 inch pine strips between the skins. If you felt you needed to increase the sheer strength of your door, you could get in there and add more pine along with adding more screws. (When building a house here in earthquake country, they call for more screws per inch along plywood sheer walls)
Ive enjoyed watching your build pmspirito,
Cheers,
Neil
