The appliances in an American motorhome come from a small group of manufacturers, and knowing which is which tells you a great deal about what will go wrong and what parts you will need.
The good news is that these are industry-standard units fitted across many RV brands, so parts are sourced on the appliance rather than on the motorhome. A Norcold cooling unit is a Norcold part whether it sits in a Winnebago or anything else.
The manufacturers you will encounter
Dometic. The largest name in RV appliances. Refrigerators, air conditioning, awnings, and through its Sealand acquisition, sanitation. Very widely fitted.
Norcold. Refrigeration specialist, extremely common in American RVs, particularly the larger absorption units.
Atwood. Water heaters, furnaces and cooktops. Now part of Dometic, though units are still referred to by the Atwood name.
Suburban. Water heaters and furnaces, and the main alternative to Atwood on most coaches.
Onan. Generators, and effectively the standard fitment on American motorhomes.
Thetford and Sealand. Toilets and sanitation systems.
Girard and Truma. Tankless water heaters on later and higher-specification vehicles.
Identify what you have before ordering anything. The data plate is usually inside the appliance access door, behind the fridge outside vent, or on the unit itself.
Refrigerators: the appliance most likely to give trouble
Most American RV fridges are absorption units, which run on gas or electricity with no compressor and no moving parts in the cooling circuit. They are silent, they work on gas away from hook-up, and they are considerably more fragile than a compressor fridge.
Common faults and what they mean:
Not cooling on gas, works on electric. Gas supply, the burner assembly, or the thermocouple. The burner jet blocks with soot and spiders, genuinely, and cleaning the burner assembly is the first job. This is a routine annual maintenance item.
Not cooling on electric, works on gas. The heating element or its thermal cut-out. Test the element for continuity.
Not cooling on either. Either the control board or the cooling unit itself. A failed cooling unit often announces itself with a yellow residue or staining behind the fridge and a faint ammonia smell. Cooling unit replacement is a substantial job, and on an older fridge the economics of replacement versus a new appliance need weighing up.
Cooling poorly in hot weather. Frequently ventilation rather than the fridge. Absorption units rely on airflow through the lower vent, up behind the unit and out of the upper vent. Blocked vents, missing baffles or debris behind the fridge all reduce performance dramatically. Check this before assuming a fault.
Cooling only when level. Normal behaviour, not a fault. Absorption fridges need the vehicle reasonably level to circulate the refrigerant. Prolonged running badly out of level can permanently damage the cooling unit.
Control board failure. Common on units of a certain age, and usually presenting as intermittent operation or failure to ignite on gas.
Water heaters
Atwood units are typically aluminium tanks without an anode rod. Suburban units use a steel tank with a porcelain lining and a sacrificial anode rod that must be replaced periodically.
That distinction matters. If you have a Suburban heater and nobody has ever changed the anode rod, the tank is corroding. Check it annually and replace when significantly depleted. An Atwood tank does not use one and fitting a rod where it does not belong is not helpful.
Common faults:
- No ignition on gas: the electrode, the gas valve, the control board, or a blocked burner
- No heat on electric: the element or the thermal cut-out
- Leaking: the tank itself, or more commonly the drain plug, the pressure relief valve or the fittings
- Repeated thermal cut-out tripping: sediment build-up in the tank, or a failing thermostat
Annual maintenance is simple: drain and flush the tank, check the anode rod on Suburban units, test the pressure relief valve, and clean the burner.
Furnaces
Suburban and Atwood forced-air furnaces are the usual fitment, ducted through the vehicle.
Common faults:
- Fan runs but no ignition: the sail switch, the electrode, the gas valve or the control board
- Ignites then cuts out: the limit switch, restricted airflow, or a blocked exhaust
- Nothing at all: power supply, thermostat or fuse
- Reduced output: blocked ducting or a partially obstructed intake
Furnaces draw significant current on 12V, so a weak battery causes symptoms that look like a furnace fault. Check battery voltage under load first, as with most RV systems.
The exhaust and intake are worth checking before every season. Insects nest in them over the summer, and a blocked exhaust is a safety matter rather than an inconvenience.
Air conditioning
Roof-mounted units, usually Dometic or Coleman. Common faults are capacitor failure, which is cheap and is the first thing to check when the compressor hums but does not start, fan motor failure, control board faults, and reduced performance from blocked filters or a dirty condenser coil.
Cleaning the filters and the coil restores performance on a surprising number of units that were assumed to be failing.
Generators
Onan sets are the standard fitment and they need running regularly. A generator that sits unused develops carburettor problems from stale fuel, which is by far the most common fault.
Run it under load for a reasonable period at least monthly, keep the oil and filters serviced to the hours schedule rather than the calendar, and use fuel stabiliser if the vehicle is stored.
Ordering the right spare
Appliance parts are model specific and often revision specific. Before ordering:
- Manufacturer and model number from the data plate
- Serial number, since parts change mid-production
- Whether the unit is gas only, electric only or dual fuel
- Photographs of the data plate and the component being replaced
Our appliances and spares range covers Dometic, Norcold, Atwood and Suburban parts held in UK stock.
Where a part is not listed, or where an older appliance needs a superseded component cross-referenced, our appliance and appliance spares finding service handles the search. A photograph of the data plate is usually all that is needed to begin.