Caravan Fridge Care: Getting the Best from Your Dometic or Thetford

Fridge Care Guide

A practical guide from Bedam Leisure — caravan & motorhome specialists

More fridge complaints reach us in a single season than almost any other subject, and the honest truth is that most of them aren't faults at all. An absorption fridge is a fussy, brilliant piece of engineering that will work beautifully for twenty years — but only if you give it the three things it actually needs. Get those right and you'll never think about it again.

As the nights draw in and the temperature starts to drop, autumn is exactly when fridge behaviour changes. So here's how the thing actually works, what to check, and what to fit before the cold arrives.

It isn't a fridge like the one at home

Your kitchen fridge has a compressor — a small motor that pumps refrigerant round a loop. The absorption fridge in most caravans and motorhomes has no moving parts at all. Instead it uses heat, from a gas flame or an electric element, to boil an ammonia and water solution. The vapour rises, condenses, and gravity feeds the liquid back down through the cooling circuit. That's the whole trick, and it's why absorption fridges are silent and love a gas bottle.

It also explains every quirk they have. Gravity does the work, so the van must be level. Heat must escape, so the vents must be clear. And the whole cycle is slow, so it needs hours, not minutes, to pull the temperature down.

1 Levelling

Level the van before you blame the fridge

This is the single most common cause of a "broken" fridge, and it is not fussiness on the manufacturer's part. Because the refrigerant returns by gravity down a gently sloping pipe, parking nose-down or leaning to one side can slow that flow or stop it entirely. Dometic's own guidance is no more than roughly three degrees out left-to-right, and they recommend keeping it level whenever you can. Thetford's troubleshooting chart puts "vehicle is not level" against both refrigerator does not start and insufficient cooling.

Three degrees is less than it sounds. Most laybys, car parks and even hardstanding pitches are deliberately built with a drainage camber. A set of ramps under the low-side wheels takes thirty seconds and solves it properly.

Leaving it unlevel overnight is worse than it looks. Running an absorption fridge badly out of level for hours risks the boiler overheating and the circuit blocking — a repair, not an adjustment. If you can't level the van, switch the fridge off rather than let it labour.

2 Ventilation

Two vents doing all the work

Look at the outside wall of your van and you'll find two grilles. The lower one draws cool air in; it rises over the cooling unit and the flue, and the hot air — plus the combustion gases when you're on gas — leaves through the upper one. Thetford is explicit that combustion gases must always discharge upwards and must never be drawn from or vented into the living area.

So the maintenance job is simple and it takes five minutes: pop the grilles off and look. Autumn is when you'll find leaf litter, cobwebs, and — every single year — a wasp or mud-dauber nest built in the warm cavity over summer. Clear it out, check the fly screen is intact, and make sure the grilles themselves aren't cracked. If a screen has perished or a vent is split, replace it; a gappy vent lets insects and rain into a compartment that really doesn't want either.

Pitching with the vents inside the awning? Thetford specifically warns to make sure the awning itself is well ventilated in that case. A sealed-up awning around the fridge vents is just a warm box, and the fridge will struggle.

3 Cooling down

Give it eight hours before you load it

Here is the tip that saves the most disappointment. Thetford's own instruction for optimal performance is to level the vehicle and switch the fridge on eight hours before placing food. Loading a warm fridge with a warm weekly shop on the morning you leave is asking it to do a day's work in an hour, and it simply can't.

Two more things worth knowing. Always start up and cool down on gas or 230V mains — the 12V supply is a holding circuit, only effective while the towing vehicle's engine is running, and it will never pull a warm fridge down. And Thetford advises cooling level 3 for ambient temperatures between 15°C and 25°C, which covers most of a British autumn; there's rarely any need to run it flat out.

4 Winter covers

Covers, and the one gas rule people get wrong

Once the outside temperature drops, that clever ventilation starts working against you — too much cold air over the cooling unit and it can't generate the temperature difference it needs. Thetford's guidance is to fit a suitable winter cover when the outside temperature is below 6°C, and to remove it again once you're back above 6°C. Dometic's covers are aimed at roughly the same window, under about 10°C or when the fridge isn't in use.

Now the important bit, and it's a safety point rather than a performance one. If you're running the fridge on mains or battery, you can cover both vents. If you're running it on gas, cover only the lower vent — the upper vent must stay open so combustion gases can escape to fresh air rather than into your van. Never block the upper vent with the gas lit.

Running a Dometic? The Dometic Winter Cover Pack for LS100/LS200 grilles (£50.99) is the matching genuine set — worth having ready before the first cold snap, as they sell through quickly in October.

5 Travel & storage

Packing it for the road, and for the layup

Before you tow, secure the contents. Raise the shelf retainers, clip the bottle retainer across the door bins, and close the door properly — a jar rolling around inside a fridge on a motorway is how shelves and bins get broken. Worth knowing the load limits too: on the N4000 series the large shelf takes 12kg, the small shelf 6kg, and the drawer 15kg.

And when the van goes into storage for the winter, the routine matters. Empty it, defrost it, clean it thoroughly, dry it, then leave both doors held open on the storage catch. A sealed damp fridge over a British winter is a mould farm. Fit the winter covers over the external vents while it's stood, and cover the vents before you pressure-wash the van — water through the grilles can damage the cooling unit.

Broken a Thetford door bin? The SR shallow door bin (£23.99) clips straight back into the door — a five-minute job and far cheaper than living with a shelf you can't use.