No real difference when running on electric or propane. All that is changed is the heat source. The absorption refrigeration will work the same whether on propane or electric. Usually it will keep the frig slighty cooler when on propane since propane is hotter and provides a higher level driving force.
The refig unit has several vessels and heat exchangers with levels in them. The concentration of the ammonia and water is controlled by the level. If the level is severely off in one vessel, the liquid has to go some where else. This will cause the concentration to go up or down depending on the vessel. The system also has a salt added which will crystallize if it is in the wrong concentrationa and wrong pressure or temperature.
The unit is "critically charged" (fixed volume of ammonia and water) and designed to operate at fixed temperatures. So level is important whether on electric or propane.
You can do a search on the net for ammonia absorption refigeration and find info on the operation or look
HERE.
Ken