The larger refrigerator does have a lower surface area to volume ratio, making it more efficient in theory.  It may have better insulation.  If the vehicle it is in is an RV, it likely has a "softer" life than the one in your van, given that the van gives a rougher ride.  That can influence the refrigerator directly, and also all the support system for it like wiring and fuse connections.  And, the family RV may be kept air conditioned all the time the refrigerator is running, while your van may not.

Your grandmother's old Serval?  Those were some awesome beasts.  BTW, one can still buy ammonia cycle refrigerators for home use, but they are very expensive, and only used for remote locations generally.

Just some thoughts.  mcneely

---- Jim Felder <jim.felder@GMAIL.COM> wrote:
> Yesterday it struck me that the dometic in my family's camper is older than
> the one in my Westy, yet it cools more like a regular refrigerator. It
> makes ice and has a small freezer compartment, like my grandmother's old
> Servell ammonia cycle refrigerator. I am trying to figure out what is it
> about the larger refrigerators that work better, if that's indeed what it
> is.
>
> Is it the size? Is it the fact that the camper fridge is almost always
> working in a temperature-controlled environment, and is never allowed to
> get really hot? If so, why did the Servell in my grandmother's house work
> so well, when it wasn't air conditioned? Is it the amount or quality of
> insulation?
>
> Just wondering, if you know.
>
> Jim

--
David McNeely