Dometic fridge 12 volt problems

[Pulsynetic]

Hi,

I am hoping some fellow caravanners might be able to help me with our Dometic fridge please. It seems that when on tow and running off the car, I switch the 12 volt red switch on which glows but its not keeping the fridge cold and by the time we get to our destination, the temperature in the fridge has gone up, with water globules on the food.
I have noticed enroute sometimes when we have stopped and left the engine running, that the red light on the 12 volt switch is no longer glowing. I didn't think that on 12 volts its run on a theromstate as the fridge is when running on mains.
I did wonder when I first noticed this it was the tow car at fault, but having recently changed our car and had the usual twin electrics fitted, but it is still happening, so not the car at fault, I am assuming.
Can anyone before I go to all the trouble of taking the fridge out which by tbe way was new 4 years ago, is there a way of testing the fridge on 12 volts to see if that is the problem, unless of course it is the car, so if anyone knows how to test that as well just to be on the safe side, i would be grateful.
Many thanks.
Ian

 

[SirRogerFFS]

Hi Ian . I will try and help you out but first of all may I ask did you leave your fridge on over night before your journey.If not that is your answer .When towing the car only keeps the temperature down. From scratch it will make little or no difference when towing.I hope this helps before you start removing it from the van.If you did leave fridge on over night ignore this message .
Sir Roger .

 

[Pulsynetic]

H Sir Roger,

Many thanks for your reply. Yes fridge was running on mains for at least 24 hours,before our departure. Caravan is stored in a small shed but will pull it out later today so I can get inside and give you the model number incase you need it.
Please let me know if you need anyother info.

All the best,
Ian

 

[Pulsynetic]

HI Sir Roger,

The fridge is a RM4210, hope this helps.

All the best,
Ian

 

[WoodlandsCamper]

Can you take your car to a specialist towbar fitting company, rather than a main dealer, and ask them to put their test board on your electrics? This should then rule out car problems and they will probably do this for free.

 

[Pulsynetic]

Hi,

Thanks for your reply. I had the towbar fitted by independent towbar company over a year ago now so not sure if they will do anything as its out of warranty now and wondered if there was anythig I could do to test both the car and the van before going back to them and playing hell, if it is the car, which I suspect it is.
Last car we had best I remember had no problems, but then the fitter did a real pucker job and soldered all the joints, didn't use the crimp type jointers. Sady he no longer fits tow bars.

All the best,
Ian

 

[TD42]

firstly , is the caravan pre or post 1997 as the auxiliary grey plug wiring for fridge & battery charging was changed in 97 ,so it would be possible that your tow bar electrics were fitted wrongly in the first place
secondly fridge 12 v supply should come direct from the battery & not picked up from somewhere in the boot & the wire for the fridge is of a larger diameter & should be separately earthed
this CC write up might help http://www.caravanclub.co.uk/media/1022790/towbar-wiring-mo.pdf

 

[Pulsynetic]

Hi TD42,

Thanks for your reply and the web link, very useful. The van is a 93 so some bit before the 97 date you mention when thigs were changed over.
As far as I know our lastcar was wired as per 97 onwards and the fridge worked on the 12 volt. Even with our currant car the red LED switch eluminates when switched on when connected to the car and with the engine tickig over. Of course it seems from the higher temperature and globules of water onthe food, its not working, which makes me wonder if its thecar at fault, perhaps bad joints so causing a voltage drop?
Sorry my knowledge of electrics is a bit limited, but looking on the web dicky joints can cause the fridge to fail.
U
Many thanks for the link, will check the grey plug and compare it with this we site.

All the best,
Ian

 

[Woodentop]

It would be of help to know (1) what your towing vehicle is and age and (2) if it has 12N/S connectors or a 13-pin.

One point that may have been overlooked is the car. If it has a manufacturer specified 13-pin towbar - such as a Westfalia or Thule on a VAG vehicle - it may not come with battery charging or fridge power wiring as standard as most continental caravans do not use this facility. As such extra wiring is necessary - a loom specifically for this task is available for VAG vehicles which costs about £100 fitted.

If you have a voltmeter check across pins 9/13 for charging volts and 10/11 for fridge volts, both with the engine running and the higher number of each pair being the negative.

 

[Pulsynetic]

Hi Woodentop,

Thanks for your reply. Yes sorry I should have mention in the beginning that it has 12 N and S plugs so twin electrics.
The car is a Citroen C4 Grand Picasso new in January 2015 the caravan is a 93 Rapido 34T which although being a direct import, (door on wrong side) is wired as per usual UK standard, but I could be wrong.
The car has a Thule towbar but with as far as I know standard twin electrics, that is what I asked for so can only presume that is what's fitted.
I will try as you suggest with a meter, but given the high pin numbers I am,assuming yu are referring to the 13 pin type connector will refer to the 12S connector pin numbers for this.
We had a Citroen C3 Picasso that gave the same problem as we found out when we went to France, had to fireit up on gas every time we stopped to try and keepthe temperature down.
Soon after that we changed the car for another C3 Picasso with EGS and had a chap remove the towbar from the first C3 and the wiring so he could putcit in the new C3. He soldered all the joints and best my wife and I can remember, the fridge ran fine on 12 volts. But..........been a bit of water under the bridge since then so we could be wrong.
Whether the soldered joints did the trick I don't know but both cars had the same electric kit.
I hope what I am writing is makig sense, I had a small stroke 3 years ago and sometimes I do make mistakes, if I have or am writing rubbish, please let me know I won't take offence. Just point out where I am in error.

All the best,
Ian

 

[Pulsynetic]

Opps,

Said I make mistakes. Just realized the door onthe van is on the near side so it was made for the UK market and assume its wiring is also as per the standard at that time in the UK.
Sorry about that.

All the best,
Ian

 

[SirRogerFFS]

Ian as Wooden top has suggested and both are good ideas checking the the wiring but also whilst you are checking just check and make doubly sure that the fridge wiring is connect to to block on the car side this one that caught me out on our X5 Wife pointed out out it worked on the previous van but obviously didnt. Good Luck and keep posting to keep us up to date..Sorry to hear about your stroke and I assure you we all can understand your posting .
Sir Roger

 

[Pulsynetic]

H Sir Roger,

Many thanks for that will check it out as suggested by Woodentop and yourself, will also take itback to where I had it fitted and get themto check it also. Glad to hear my threads are making sense, as I know sometimes when writing tigs do go a bit wonky.
Will keep you posted as to how thibgs work out, as its very anounying the fridge is not keeping cool as itshould when onthe move.

Many thanks to everyone who has replied to my thread, realky is much appreciated.

All the best,
Ian

 

[Pulsynetic]

Hi,

As requested I have an update on my fridge problems when running off the car. Seems it is the car as I suspected it might be.
Was passing the caravan place we have the van serviced at, nice people I pulled inand asked if they could test the car and they soon put a test meter on. At first all worked fine, all the lights on his gismo that should be on were, then after a minute or so things started to go pear shaped and the light that indicates power going to the fridge went off and no amount of reving would make it come back on.
So something wrong he said with the relay, so will have to take it back to where it was fitted and see if they will put it right, as its not worked since they did it a year ago.
Will update again as and when we get it fixed.

All the best,
Ian

 

[SirRogerFFS]

Well done Ian at least the cost should be minimal.Thanks for keeping us posted,its nice to know where and how posters get on with our suggestions.
Sir Roger

 

[Pulsynetic]

Thanks Dir Roger, I am hooing they will sort it out free of charge, but I am not hodig my breath on that one. Trouble is these C4 Grand Picasso's 7 seat models are very involved with regards getting at the electrics, a great deal of the cars rear interior has to be removed, which is very time consuming.
But we shall see, will let you now how it goes.

All the best,
Ian

 

[swpostie]

I would expect the relay to be under the bonnet (assuming the battery is there), and should only cost a few quid.

Hopefully a cheap fix.

 

[Dustydog]

http://www.towitall.co.uk/faq/1.aspx
Ian
See above link. Hopefully your car relay is the culprit. However the fridge pulls a high amperage through the 12volt 12s plug and socket. As the pin begins to burn out a high resistance ocurrs causing the symptoms you have.
No matter what, may I suggest you have the above modification carried out.

 

[Pulsynetic]

Hi swpostle,

Thanks you have raise a good point, be great if it is under the bonnet the battery is. But I have a sneaky feeling they picked up the power in the glove compartment where the fuse box is and so the relay could be there, but I think its more likely its behind the interior covering at the rear of the car.
Will have a look, never know your luck. Thanks

All the best,
Ian

 

[Pulsynetic]

Hi Dustdog,

Many thanks for the link, certainly worth thinking about if it can't be sorted as it is at the moment.

All the best,
Ian

 

[swpostie]

Hi swpostle,

Thanks you have raise a good point, be great if it is under the bonnet the battery is. But I have a sneaky feeling they picked up the power in the glove compartment where the fuse box is and so the relay could be there, but I think its more likely its behind the interior covering at the rear of the car.
Will have a look, never know your luck. Thanks

All the best,
Ian

The glove box would be okay wouldn't it? Why do you think it's behind the interior covering at the rear of the car?

If you had to fit it where would you put it? Under the bonnet, where it's easy, or in the back - where it's much fiddler?

 

[Woodentop]

They may well have picked up the 12V from a spare fuse placing in the fusebox, but usually they run one cable that feeds a voltage sensitive relay located at the rear. The supply cable goes straight through and feeds the caravan battery charging connection: the fridge tees off, through the voltage sensitive relay, and feeds the fridge connection. Most of these modules have a small adjuster on one end: if you can find it set the engine running and measure the volts on the fridge feed. If it is zero adjust the control very slowly until the relay clicks and the fridge gets 12V. Stop the engine and make sure the fridge supply disappears after a second or two.

 

[Pulsynetic]

Hi folks,

As requested an update on my fridge running on 12 volts or the lack of. Pleased to report it is now running on 12 volts when I connected the car, the altimate test will be when we go on a longish trip, but hooking up to the car and stop starting a few times, all worked OK with the red light staying on as it should.
Thankfully the chap who did my previous car came out and he changed the relay, although when he put a meter on it, it was workibg fine. He also put a larger relay on as it was a 20 amp relay, although given the size of the fridge 20 amp would or should have been enough.
But whether the relay was faulty or just not large enough, all seems OK now and look forward to having a nice cold fridge from now on. Fingers crossed.

Many thanks to everyone who replied with help to our problem, have a great summer touring.

All the best,
Ian