Thetford code 10

[mart-hart]

My Thetford fridge wont work on 12 v on my Abby caravan. I get code 10 and flashing blue light although it works fine on 240v.
So far I have.
Put a new 13 core and plug on as the old one was tatty.
replaced all the 20 amp fuses with new ones (I assume its a 20 amp circuit)
Given the fridge a nice clean earth on the car side.
Started the car and gave it some revs.
Taken the outside vents off but cant see any wires that are checkable.
Looking for something I may have missed as I dont want to take the fridge out at the start of spring.

 

[mart-hart]

Mode; N112-N43F0426E

When I first tried the fridge on 12v before I put new wiring there was a loud clicking from behind the fridge as if a selanoid was tring to connect but that has stopped.

 

[Jcloughie]

Hi mart-hat and welcome to the forum. You seem to be looking into it sensibly. It might be that the element is broken. It’s not that much of a problem that might interfere with get aways. To help with keeping things cool we use ice packs and frozen bottles of milk for the journey. As the cooling from the 12 volt ain’t that great anyway.


John

 

[RogerL]

Hi mart-hat and welcome to the forum. You seem to be looking into it sensibly. It might be that the element is broken. It’s not that much of a problem that might interfere with get aways. To help with keeping things cool we use ice packs and frozen bottles of milk for the journey. As the cooling from the 12 volt ain’t that great anyway.


John

12 volt power ratings for caravan fridges are the same or similar to the 230 V ratings - neither will cool a fridge right down in the short period of a tow to site so pre-cooling is necessary.

 

[mart-hart]

Thanks. I need to take my frozen food, Im on a special diet.

 

[otherclive]

When travelling in warmer weather we would precook the fridge at home and then pack it with stuff that just required to be kept cool but not frozen. For food that was more critic we used Coleman Extreme thermal container and when packed with frozen food and freezer blocks that would keep stuff frozen for at least two days if no opened regularly.

 

[mart-hart]

When travelling in warmer weather we would precook the fridge at home and then pack it with stuff that just required to be kept cool but not frozen. For food that was more critic we used Coleman Extreme thermal container and when packed with frozen food and freezer blocks that would keep stuff frozen for at least two days if no opened regularly.

They are not cheep are they, I would by a portable freezer if it comes to that. See if I can get the fridge working first.

 

[Jcloughie]

12 volt power ratings for caravan fridges are the same or similar to the 230 V ratings - neither will cool a fridge right down in the short period of a tow to site so pre-cooling is necessary.

You are correct, but in my experience in real life the 12volt seems to have only a small affect on cooling. Even a fridge that is pre-cooled suffers on a long journey. Out of curiosity I just looked up the specification, but could not find a Thetford example. But a Dometic one shows this:



So just 5 watts in it! Yet the mains is thermostatically controlled and the 12 volt constant, suggesting the 12volt should be more effective. So to me, it’s a mystery.

John

 

[Parksy]

Hi Mart-Hart

This link to a comment from a wild camping site might be useful.
It's worth having a look at the terminal block.

 

[mart-hart]

Hi Mart-Hart

This link to a comment from a wild camping site might be useful.
It's worth having a look at the terminal block.

I wish I could get to the electrics through the vents but there is nothing. Interesting though, something to check when and if I take the fridge out.

 

[RogerL]

You are correct, but in my experience in real life the 12volt seems to have only a small affect on cooling. Even a fridge that is pre-cooled suffers on a long journey. Out of curiosity I just looked up the specification, but could not find a Thetford example. But a Dometic one shows this:

View attachment 2975

So just 5 watts in it! Yet the mains is thermostatically controlled and the 12 volt constant, suggesting the 12volt should be more effective. So to me, it’s a mystery.

John

It's not much of a mystery - many cars and caravans have minimum gauge wiring for the fridge circuit and due to the distance from car alternator to caravan fridge, and back, many outfits suffer from voltage drop and although the alternator may be putting out 14v or more, the fridge may only be seeing 10v or less - the power for the 12v element is proportional to the voltage so may be significantly below the rated output.

The answer is to use 30 amp cabling even though the current draw is only 10 amps.

 

[RogerL]

I wish I could get to the electrics through the vents but there is nothing. Interesting though, something to check when and if I take the fridge out.

Taking the vent out should give you access to the fridge electrics.

 

[mart-hart]

Taking the vent out should give you access to the fridge electrics.

I guess it depends on the model of caravan/fridge, but please believe me it doesn't . I can see them with a torch and mirror but no way can you get to them.

 

[Jcloughie]

It's not much of a mystery - many cars and caravans have minimum gauge wiring for the fridge circuit and due to the distance from car alternator to caravan fridge, and back, many outfits suffer from voltage drop and although the alternator may be putting out 14v or more, the fridge may only be seeing 10v or less - the power for the 12v element is proportional to the voltage so may be significantly below the rated output.

The answer is to use 30 amp cabling even though the current draw is only 10 amps.

Absolutely correct. Don’t know what my present wiring is as it was installed byVolvo. But when I have wired my own cars, and I have done many. I always run a very heavy cable to the boot, even 10mm. But the distance is still the same. Results might be slightly improved, but not sufficiently, hence poorer cooling.


John

 

[mart-hart]

Up date* when I try the 12v outlets in my caravan they work fine on caravan and car UNTIL. I start the car engine then they stop.
Where the fridge feed comes into the caravan its still showing 13 volts.
So there must be something in the caravan electrics giving me pain. any idea?

 

[Jcloughie]

Up date* when I try the 12v outlets in my caravan they work fine on caravan and car UNTIL. I start the car engine then they stop.
Where the fridge feed comes into the caravan its still showing 13 volts.
So there must be something in the caravan electrics giving me pain. any idea?
Testing the wires into the caravan power from car battery dies when I start the engine.

No, that bit is normal. When the car is connected the habitation relay comes to life and cutts off the 12 volt system. However, the 12 volt feed to the fridge should not be affected by this,

Can you get to the connection point that feeds the fridge heater and see what voltage you have there with engine on?

John

 

[mart-hart]

Thanks john, well you cleared that up for me. I wanted to see if I could carry a 12v freezer in the van, Maybe I need to get a feed for it from somewhere else. Maybe direct to battery and the car will charge it and run off caravan battery when stopped.
I know people will get over it with ice packs bu I need frozen food for my special diet.

No cant get anywhere near the fridge electrics at the fridge.

 

[Jcloughie]

It would be easier to put it in the boot if possible. The added amperage might be too much for the 13 pin feed, and if you put another wire to run with it, which is feasible, there may be excessive voltage drop. Particularly if you have a compressor freezer.

John

 

[mart-hart]

Ok I can do that.
Whilst tracing wires around and driving the wife mad unpacking everything I have had another look at the feed to the fridge.
There are 4 wires going to it. 2 very fine and another 2 that are about 2.5
A red one and a black and white one.
Traced these back to the fuse box and there is no power going through them.
All the fuses are new so is there some sort of relay there .

 

[Jcloughie]

Ok I can do that.
Whilst tracing wires around and driving the wife mad unpacking everything I have had another look at the feed to the fridge.
There are 4 wires going to it. 2 very fine and another 2 that are about 2.5
A red one and a black and white one.
Traced these back to the fuse box and there is no power going through them.
All the fuses are new so is there some sort of relay there .

Sounds like you are checking the right wires. Did you check with engine running?

If so, the fault is before this, the 12 pin plug or socket, or the power relay on the car.


Have you checked power between 10 and 11, engine running?



John

 

[mart-hart]

yes car running,switch to car.
So at the fuse box I have 13.5 v going in and nothing coming out.
Thinking of scotch locks and bridging the fuse box out.

 

[mart-hart]

Interesting development.
When I first tried the fridge on 12 there was a clicking from the fridge.

Now I have bridged the feed to the fridge (yes im a Back street bodger) and I am getting.
Clicking from the fridge.
clicking from a little box on the fuse box.

 

[Jcloughie]

Perhaps you are powering the igniter circuit. And hearing the click from the piezo firing.

John

 

[mart-hart]

No its not the piezo very different noise.

My guess, the solenoid has gone on the fridge causing the same to go at the fuse box and then getting no voltage threw me totally.

So its not a quick fix.