The information you have posted regarding the vent/ducting for the fridge.
E1.5 Exhaust gas duct and installing the fume flue
The exhaust gas duct system must be made in
such a manner as to achieve a complete extraction
of combustion products to the outside of
living space. The duct system must slope in an
upward direction in order to avoid a build-up of
condensate. The type of exhaust gas duct
shown in Fig. E22 allows the side installation of
the winter cover.
is for a side mount vent. This is where the fridge is ducted and vented through the side of the trailer.
Escape vents the trailers using a roof mount vent. There is low vent on the side of the trailer and an upper vent on the roof of the trailer.
When the poor cooling performance with the fridge arose Escape Trailer Industries recorded and documented in detail the installation method of the fridge and fridge vent sizes used. This is the first place Dometic looked for fault regarding performance failure. Dometic's tech's, then reviewed this information and they could see no fault with the installation as it met all of their requirements.