Propane refrigerators draw their cooling air from the outside and exhaust
it to the outside. If one is installed so that it draws from the interior
it is a faulty installation.
The exhaust from the burner goes right up the same vent path as the heat
from the coils (condenser). We don't want the exhaust to have any way to
get into the trailer interior while we're sleeping.
Ovens and ranges exhaust to the interior but they are not normally used
while we're sleeping. Plus there should be an exhaust.
Al