Problem Dometic Fridge

Hi everybody. I have since posting the above found some information about our Dometic fridge. I didn't know that the fridge would only work on 12v when the engine is running. As it only took me 45 mins to get to Clumber Park, the fridge really didn't have enough time to cool down, and of course turning the engine off when we parked meant the fridge was not operable. At least I now know why it didn't get cold.

What I would like to know is, does anyone know where the fuses for the fridge are located as there is no reference to it in the Swift Motorhome manual, and the Fiat handbook only deals with things relating to the Fiat engine and chassis. Once again any help would be appreciated. BTW, I have a 2006 Swift Lifestyle 590RS.

according to the Sargent website, wiring diagrams, it should be large fuse no2, rated 15 amp.

is the fridge working on EHU, not apparent from ypur post.

is the fridge working on gas, again, not mentioned in your post.

after 45 mins driving, the fridge should be a bit colder on 12v.

good luck.

Many people plug their motorhome, or caravan, into an electric supply for a few hours, before setting off to get it cold more quickly.  You can also help the cooling process by packing it full of pre-frozen stuff - even milk, cartons of orange juice, bacon, etc., which if left in the fridge will slowly thaw.

I suspect that whilst 12v might maintain a cool temperature it is unlikely to have much impact on a warm fridge. I never turn our caravan fridge to 12 volt when we tow. We always turn fridge on a couple of days ahead when at home on EHU. After the first day I pack ready for the off the next day. 

I was informed that the 12v when you are travelling will only keep the fridge temperature at what it is when you start driving, so either cool down on mains electric or gas before driving then turn on to 12v to maintain the temperature. if this is not correct let us know, but this is the way we have always done it.

Hello everybody. Apologies for not answering your comments on my (apparent) fridge problem. I have not been on the forum for some time.The fridge problem was pilot error!.

Packing the fridge full of stuff before it was cooled down, I found out is not the answer. I found some advice to cool the empty fridge down the day before traveling on gas, then turn it on to 12v whilst traveling to keep the temperature the same, and then switch to 240v when at the destination site on EHU, and this worked an absolute treat. Once again, thank you all for your very helpful comments, and wishing everybody a very happy and trouble free season.

In most caravanners cases, the above is true i.e. the 12v operation usually only holds the fridge at temperature, it will not cool it from warm. This is not actually correct, in most cases this is caused by poor installation of the caravans' auxiliary supplies and the use of Voltage Sensing Relays (VSR's) which are not adjusted correctly and/or are fitted to towcars with Smart alternators, thus causing the VSR's to keep tripping in & out etc. If for instance 2 x 6mm² cables are installed directly from the towcars’ battery to the rear of the vehicle to supply the caravans’ auxiliaries ( europlug pins 9 & 10, chassis for earth returns), this will have a much less voltage drop on the 10 amp fridge loadings. Then using an alternative method for controlling the ignition switched (engine running) supply to the fridge that is constant and not affected by voltage drop as per VSR’s, then in most cases the fridge will actually cool on 12v and even ice-up the freezer, mine does and so do many others where I’ve installed the auxiliary supplies to towcars. Just to mention, if your towcar is very moden and has a Regenerative Braking Smart Alternator in order to achieve the above fridge efficiency you may have to fork-out for a Wildside Module, please view the link.

 https://cdn.shopify.com/s/files/1/0658/7343/files/Page16_CaravanWildside.pdf?6047287793136132886

PS, one of the most common causes of poor fridge operation when operating on 12v is that cow-boy tow-bar fitting companies install VSR's at the rear of the towcar and in which the VSR's circuitry voltage is dragged down by the leisure battery charging and the fridges' 10 amp loadings. The VSR should always be mounted at the front of the towcar near the vehicle battery and its main power supply must be at least 4mm² or 6mm² for optimum efficiency. This means that the caravans' fridge & leisure battery loadings at the rear of the vehicle cannot drag-down the supply voltage to the VSR which is mega close to the vehicle battery, this also aids better compatibility with first generation smart alternators, although smart alternators and VSR's don't mix as a rule. Towcars fitted with second generation, regenerative braking type alternators, the caravan will need to be fitted with said Wildside module for optimum efficiency. Switching on the vehicles' headlights when towing can often help towcars fitted with a smart alternator where the VSR has been fitted at the rear and the vehicle! Temp-quick-fix possibly? Who am I to say what is right or wrong?

• Well, I have found what you say very interesting Snowy. You seem to know more than most on this subject and thanks for passing it on. I will print out your link when I get back. I have a 21yr old Toyota Surf so I don't have a smart alternator! However your comments re direct wiring of pins 9&10 is very interesting. If I haven't got a VSR would the wiring of 9 &10 still be applicable ?

Hi Merve,

To answer your question; If your towcar is not fitted with a VSR and the caravans' fridge supply is controlled by other means, you will still benefit wiring your towcars' auxiliary supplies (pins 9 & 10) directly to your vehicle battery using 2 x 6mm² cable i.e. next to no voltage drop at the rear of the towcar. You must of course, fuse both supplies as close to the vehicles’ battery as possible.

This maybe of interest to some; Modern vehicles now have Can-bus multiplex wiring as you well know, this means that most vehicles have electronic modules at the rear of the vehicle, usually behind the boot lining or similar location. These modules are usually supplied with quite large gauge supply cables, for easy installation of the caravan auxiliaries, many cow-boy towbar fitting companies tap into these cables, this can cause problems, this is why I always recommend installing new wiring directly to the vehicles’ battery for said caravan auxiliaries.

So what are these possible problems? The caravans’ fridge usually draws around 10 amps unless it is one of the newer type that has a silent running compressor, Your caravans’ leisure battery charging could quite easily be drawing 20 amps at the start if you have been using your mover, 30 amps thus far, not to mention possible AL-KO ATC operation! This loading can cause voltage drop to the module(s) at the rear of the vehicle, the towcars ECU does not know why? It does not know why there is a large current drain, if thinks there is a fault, it sometimes may try to alter settings to try to compensate, this can cause loss of power or even put the vehicle into limp-mode. In other words, tapping into these cables can be a minefield! I recommend you not to do it.