12v Fridge while driving....

[Tom Robinson]

Hey folks

I'm new to this and my family are on our first caravan trip, two days in!

Is the caravan light supposed to come on when connected to the car? I have read somewhere that the light and 12v cooler are on different circuits? I'd like to know whether the fridge is working on 12V when I'm driving or not.

The van is a 2006 Compass Magnum and the fridge is a Thetford N80p. My car has a 13 pin socket and I'm using an adapter to connect the 7n and 7s from my van.
Pin 10 from my car is kicking out voltage and all electrics stop working in the van when the car is connected, I think this is correct.
When the car isn't connected, the fuse for fridge in the van doesn't seem to do anything (to the fridge light at least) but the fuse for ignition stops the fridge light from working.

The fridge works on hook up and gas so I know that the cooling mechanism works ok. Has anyone got any ideas before I take to a garage to look at it?

Thanks folks!

 

[audiorob]

Not quite sure I can follow all of your description but will attempt to give a few pointers.
When pitched the fridge will work on gas or UHU. It does use 12v from the caravan supply for the internal light - there is a magnetic switch in the fridge door surround that senses when the door is open and switches it on.
It will only work on 12 v when towing, and the towbar should be wired so that the supply only operates through a relay when the ignition is on and the engine is running - otherwise the fridge would rapidly flatten the battery. Likely you will find that the electric switch on the fridge has an O for off and an electric and battery symbol, so switch to the battery position when you are towing .- not forgetting to turn back to electric when you are pitched.

 

[Tom Robinson]

That’s really useful, thank you. I was just wondering if other fridges have the Interior light on when towing? I had thought that the fridge wasn’t working while towing but have read somewhere that the fridge and the interior fridge light are in separate circuits. This would make sense as hitching up the car disables all other power from the van, including the interior fridge light.

 

[ProfJohnL]

... This would make sense as hitching up the car disables all other power from the van, including the interior fridge light.

I'm wondering what makes you suspect the fridge isn't working on car power?

I would certainly guess that the fridges 12V control circuit which sorts out teh gas ignition and the internal light should be connected to the caravans habitation 12V supply. Consequently when car power is available teh habitation relay cuts the power to all the caravans habitation equipment (inc fridge control) circuits

I d agree your description suggests the habitation relay is working, and that at least means car power is getting to the auxiliary charging and fridge power circuits.

The simplest way to check is to allow the fridge to come up to close to room temperature, then get in the car and tow it for half an hour then check the Evaporator coil inside the fridge gets cold.

Alternatively if you have a multi-meter with at least 10A current measuring capacity, remove the fridges big fuse and check for about 8A across its contacts when the car is connected and the engine is revved to make sure the alternator is putting out enough power.

 

[Buckman]

On many cars the fridge will not work properly on the 12v when connected due to the alternator of a modern car which does not supply 12v continiously. We have this issue with the Jeep. I am not sure of the technical issues but I am sure some one will be along to elaborate and give the correct advice.

 

[RogerL]

On many cars the fridge will not work properly on the 12v when connected due to the alternator of a modern car which does not supply 12v continiously. We have this issue with the Jeep. I am not sure of the technical issues but I am sure some one will be along to elaborate and give the correct advice.

It's all to do with smart alternators which don't charge full-time and so-called "smart" voltage-sensitive relays (VSRs) which therefore cut the fridge power supply.

Best answer, IMO, is to use a proper auto-electrician, not a towbar fitter.