Why your RV fridge will not cool on propane

An absorption refrigerator has no compressor and no moving parts in its cooling circuit. It boils an ammonia solution with a heat source and lets physics do the rest, which means a fridge that works on shore power but not on gas has almost always lost the heat source rather than the cooling unit. That narrows the problem enormously, and it means the diagnosis is a sequence rather than a guess.

The details

Start at the tank, because roughly a third of these calls end there. Is the cylinder actually open, is there gas in it, and does another propane appliance light? A stove burner that lights and holds is a two-minute proof that supply, regulator and manifold are all doing their jobs. If the stove will not light either, the fridge is not the fault and the search moves to the regulator. Note also that the excess-flow device in the cylinder valve can trip if the tank is opened fast against an open appliance — close everything, open the cylinder slowly, and try again before condemning anything.

Next is the ignition sequence, and this is where you use your ears. On the gas cycle the control board should click repeatedly at the burner while it tries to light. Clicking and no flame means gas is not arriving at the burner or is not arriving cleanly. Flame that lights and then goes out after a few seconds is a flame-sense failure — the board lit it, could not confirm it, and shut the gas off as designed. Those two symptoms point at different components and telling them apart saves a great deal of time.

If it is lighting and dying, or burning yellow and lazy, the burner assembly is the usual answer. The orifice is a precisely sized hole and it does not take much to disrupt it: spiders in particular are drawn to the odorant in propane and build nests in burner tubes, which is one of the classic RV faults and is far more common on a rig that has sat between seasons. Cleaning a burner and orifice is careful work with the right tools and it is not a job to improvise around an open gas line.

Then the two installation faults that masquerade as component failures. Levelling: an absorption unit relies on gravity to return liquid through its circuit, and a rig parked significantly off level — especially side to side, and especially for hours — can stall that circulation and in the worst case damage the cooling unit permanently. And airflow: the fridge dumps its heat through the sidewall or roof vent, and a blocked, nested or wasp-filled vent chimney will leave a perfectly functional fridge unable to cool no matter what the burner is doing.

There is an Outer Banks version of every one of these. Rigs here spend weeks on end off shore power — at Ocracoke, at Cape Point, at Frisco, everywhere except the 47 sites with electricity and water at Oregon Inlet — so the gas cycle is not a backup here, it is the primary mode, and a fault that would be invisible on a full hookup site ends a holiday. Salt air is hard on the sheet-metal components behind the vent door, and the wind blows fine sand into every exterior opening on the rig including that one.

Two things not to do. Do not attempt to modify or bypass gas components, and do not run an unlit gas cycle repeatedly hoping it catches — the propane goes somewhere. And do not count on beach-side boondocking as a workaround while you sort it out, because no beach camping at this seashore and the only legal overnight options are the campgrounds. If the sequence above has not found it within a couple of steps, that is the point to hand it to someone with a manometer and a thermocouple tester rather than to keep going. Even on a rig at the full 45 feet of legal length, this is a small, self-contained repair when it is diagnosed properly.

Supply, ignition, burner, level, airflow — in that order. Most gas-side fridge faults are found in the first three steps, and almost none of them are the cooling unit people fear.