Dometic RML 10.4G, RML 10.4P

Climate class SN (which Dometic calls 'Extended Temperate') means the fridge is designed to work reliably when the air temperature is from +10°C up to +32°C (taken at the bottom vent grille, outside the vehicle).

In a hot summer the outside temperature often reaches about 32°C - the top of the fridge's rated range - and once it climbs higher, the temperature inside the fridge will inevitably rise. An absorption fridge needs a heat source to move its refrigerant around the cooling unit (which is why it can run on 12V, 230V or gas), so it has to get rid of the heat from its power source as well as the heat drawn out of the food compartment.

To help it in hot weather: park where the fridge vents get as much shade as possible during the day; unclip the outside vent grilles to improve airflow; and if you regularly travel somewhere hot, consider having a ventilator kit (a fan fitted behind the fridge) installed to boost the airflow - Dometic lists these among its accessories.

Dometic's 2023 'New for old - simply swap' guide covers both its absorption and compressor fridges, showing which current models replace older ones. It's available from the catalogues section of Dometic's website.

Check the fuse in the mains supply and replace it if it has blown, and make sure the vehicle is actually plugged into a mains supply. If both are fine, the AC heating element may have failed - that needs an authorised Dometic service centre.

Possible causes, and what to do: the vehicle's own fuse has blown - replace it (see the vehicle's handbook); the vehicle battery is flat - test it and recharge it; the ignition is off - switch it on. If the fuse in the fridge's DC cable has blown (the fuse on the relay) or the DC heating element has failed, contact an authorised Dometic service centre.

Check the gas cylinder isn't empty (change it if it is) and that the gas valve is turned on. If air has got into the gas pipe, turn the fridge off and on again, repeating this three or four times if needed; if a gas hob or cooker is fitted, switch that on, then try the fridge again if needed.

The mains voltage is too low. The fridge switches back to mains by itself once the supply voltage recovers.

Work through the likely causes: the cooling unit isn't getting enough air - make sure the outside vent grilles aren't blocked; the evaporator has iced up - check the door shuts properly and the seal is seated and undamaged, then defrost the fridge; the temperature setting is too warm - turn it to a colder setting; it's very hot outside - take the vent grille off for a while so hot air can escape faster; too much food, or too much warm food, went in at once - take some out, and let warm food cool before putting it back; the fridge was only switched on recently - give it four to five hours, then recheck the temperature.

These codes apply to Dometic's 10-series fridges.

• W01: the temperature sensor in the fridge compartment is faulty - contact an authorised Dometic service centre.
• W05: no AC (mains) power, or the AC voltage is wrong - connect a supply, or choose another energy source such as gas.
• W06: no DC power - connect the fridge to DC power, or choose another energy source such as gas or mains AC.

W10 with a beep: the door has been left open longer than 2 minutes - close it. W11: DC overvoltage (above 16V) - reduce the DC supply voltage.

ERROR-type faults on Dometic's 10-series fridges have to be reset by hand: on the RM10.5T, RMS10.5T and RMS10.5XT, hold the control knob in for 2 seconds; on the RM10.5S, RMS10.5S and RMS10.5XS, press and hold for 2 seconds. You'll hear a beep once the error is cleared.

• E03: the power module and display aren't communicating - contact an authorised Dometic service centre.
• E07, E08 and E09: no cooling in gas, AC (mains) or DC mode respectively - check the fridge (and the vehicle) is level and correct it if needed, then reset the error; if it comes back, contact Dometic customer service.
• E12 (gas valve test failed) and E13 (internal communication fault) both stop gas operation - reset the error, and contact customer service if it returns.
• E14: the battery packs that power it in stand-alone gas mode have run down - fit fresh batteries before resetting the error.
• E50: gas has locked out after 3 failed ignition attempts, usually because the gas cylinder is empty - change the cylinder, then reset the error.
• E51 (gas lock-out from an internal power-module fault), E52 (gas valve earth fault) and E53 (ignition electrode earth fault): reset the error, and contact customer service if it happens again.