Gas refrigerators
They had a burner that heated ammonia as a refrigerant. The fridge would use electricity to operate the ice-maker or defrost timer. If not equipped with defrost timer or icemaker, the unit indeed would use no electricity.
Why didn't GAS refrigerators persist? Dunno. My aunt had a Whirlpool gas in the 1960s WITH an icemaker! Their popularity in the home seems to have faded after that. You can still buy these "absorption" refrigerators generally for RV use to this day.
If not perfectly maintained, older GAS refrigerators emitted carbon-monoxide gas which resulted in numerous deaths. Since Servel was among the few (if only) gas refrigerator makers of the time, and probably the most popular, their stuff was probably targeted as the refrigerators aged and deaths increased.
I thought Servel's agreement with Electrolux to make the guts ended and Whirlpool bought up Servel to get the icemaker patents?
This I am not clear on. Perhaps the group knows.