Friday, October 7, 2022


Ask Dave: Switching RV fridge from propane to 120v, will there be a cooling gap?

Dear Dave,
If my RV’s fridge is operating on propane and we switch over to 120v, is there a time lapse in the cooling? In other words, does the change require a whole new “spool-up” time? —Tommy

Dear Tommy,
You would not have any more of a delay in the refrigerator operation as you do when it is running on 120-volt power or propane normally. The thermistor inside the refrigerator is the temperature sensor. It sends the information to the eyebrow board that you set the temperature on.

When you are running on propane, the module board calls for cooling and opens the gas valve. It creates a spark that produces a flame, which heats the rich solution in the burner vessel and starts the absorption process that draws heat out of the evaporator coils in the RV fridge.

Running the RV fridge on 120-volt power

When you run on 120-volt power, the same process occurs and a 120-volt heating element heats the solution. Both operations shut down when the desired temperature is sensed by the thermistor in the RV fridge compartment. It does not run all the time. So if you are running on propane and switch to 120-volt mode, there will be no new “spool-up” time. Rather, it will be the normal operation of heating the rich solution and starting the absorption process again.

This diagram shows where the electric heater is located beside the pump tube. The picture below is what it looks like from the outside vent. The LP gas burner is located in the small metal box in the lower right, which is a swivel site hole. The electric heater cannot be seen; however, the wires are going up to it. Larger refrigerators will have two heaters.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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Tommy Molnar
6 months ago

Good explanation on how this all works. Thanks Dave.

John Goodell
6 months ago

It’s interesting that your schematic shows the BAFFLE in the chimney! Since we usually camp with electric service it took me a while to realize that my fridge didn’t cool on propane, only on electric. It took me a few years of research to discover that the BAFFLE was missing and it is ESSENTIAL for propane operation! $22 on Amazon!