Dometic CRX Fridge not cooling - FIXED!!

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Robsey
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Dometic CRX Fridge not cooling - FIXED!!

Post by Robsey »

Hi all - Am I on the right track with this.?
It is for a diffrrent VW, but just as relevant if you have a fridge in your camper van

Query is whether the factory wiring harness for a fridge can cause this fault in a VW Crafter High Top, Long Wheel Base camper van. (2014 / 64 plate).
Not mine obviously...
It belongs to my Clinical Lead.

She has reported problems with her Dometic CRX fridge not working.
All the relevant lights come on, but it simply does not cool down.
There is the flashing orange sensor-fault light, but I believe that is a red herring.

Image

After a lot of googling, I discovered that the biggest issue is with the power feed cables being too thin to carry adequate current, or resulting in excessive losses over the 3 metre cable distance from the leisure battery.

All very odd as it has a 15amp inline blade fuse.

Further research found that a company makes beefier cables to cure this problem.
The company quotes 6mm csa cable...
To bring this into perspective - the fusebox to ignition switch feed on my T25 is only 4mm CSA, and that feeds everything on the van.
Except the starter, which has 6mm csa cabling to minimise losses over the 4 metre cable run;
and the main starter battery to fuse box cable which is also 6mm csa.

Anyway - as with many items at the moment, they are currently out of stock.

So - this is the plan.
It is really very simple.
3 metre long cables
One for battery positive feed.
And one for return to battery negative.
- 8mm eyelet at one end and a sturdy female spade and insulator at the other end.
The positive cable has a 15 amp fuse at the battery end and a little male spade tail at the fridge end for a fan to connect to.

Due to the thickness, I used a gas ring on my cooker to heat the cables enough for the connectors to be soldered effectively.
I always crimp, solder and heat-shrink tube all my wiring.
On heavy stuff, good insulation and security is imperative.

Image

The real test will be on Friday when we test my loom and see if it sorts her fridge issue.
Fingers crossed.

I have mentioned that I am not a fan of the connector block that the conversion company installed for the previous owner.
A bit rough, but I suppose it fulfils a need.

Image

I suspect using the middle post and a link cable to the right-hand post for the negative rail will not help either.

And the leisure battery - strapped back, rather than clamped in situ.

Image
Last edited by Robsey on 31 Jul 2022, 11:13, edited 3 times in total.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished

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Mocki
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Re: Dometic CRX Fridge not cooling

Post by Mocki »

Frankly you need to be using the chassis as neg and running the fridge direct from the battery via its own inline fuse, not going through that heath robinson mash up in you picture .
Voltage drop will be the issue , although i thought the flashing amber light also warning of temperature sensor issues ??
Steve
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Robsey
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Re: Dometic CRX Fridge not cooling - FIXED !!

Post by Robsey »

Yes, you are correct that the flashing amber light that looks like a kettle bar-be-que symbol is indeed meant to indicate a faulty sensor.

I have googled like a possessed fool for answers, but nowhere does anyone actually change the temperature sensor.

In fact - nowhere does it tell you how to change the sensor, apart from the odd American youtube video for a totally different make / model / layout of fridge.

And we have downloaded the user manual complete with basic tests. Nothing shows the location and method of replacement of the sensor.

There are dozens of threads that regardless of the indicated fault, they all end up using beefier wiring to achieve a fix.

I personally would rip out that crazy terminal post concoction and use proper insulated junction enclosures, or wire directly to the terminals of the leisure battery.

The existing wires in her photos look like maximum 2.5mm csa, which should still be enough for 15 amps.
And then the additional daisy chain because the negative wire does not reach the main negative post makes the whole thing look destined to fail.

I have also told her to try the whole thing with the engine running, potentially increasing the battery voltage during charging.
This allegedly did not make any difference.

I am not sure if it works on hook-up, as she usually camps "off grid".

Normally, I would tell her to take it to a Dometic installer, but I believe their customer service is poor, and she is due to go away to Scotland in a couple of weeks.
People always report problems at a last minute panic...

Therefore I have made up a beefy loom from salvage cables and spare connectors.
I have been thorough in making up the cables, because if it works, then I know that it is safe, and not just a dodgy last-minute quick fix.

As said - hopefully Friday will show one way or the other, when I finally get to look at the van and diagnose issues in the flesh - so to speak.
Last edited by Robsey on 29 Jul 2022, 20:50, edited 1 time in total.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished

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Robsey
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Re: Dometic CRX Fridge not cooling - FIXED !!

Post by Robsey »

I fitted 6mm cables, and it is working perfectly.
Compressor and temperature leds are blue.
No nasty orange - pah!

Phew!!

Wired directly to the leisure battery via the recommended 15amp fuse.
Fuse very close to the battery.

There was a 10amp fuse in the "speaker wire" size cables fitted by the initial installer.
It looks like it is "factory spec" judging by how it is tied back tidily to the rest of the fridge cabinet.
Oddly the 10amp fuse was at the fridge end, not the battery end.
Obviously some people have no idea about basic electrics.

So - all good :ok
Lets hope she does not break anything else :rofl

UPDATE - I have just seen how much these things cost. :shock:
£1000 for a poxy fridge with naff skinny wiring. Yikes!!

So before you tip out your dodgy fridge. Put a decent cable on first. It could save you paying out a fortune to replace something that isn't broken.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished

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Re: Dometic CRX Fridge not cooling - FIXED!!

Post by silverbullet »

Waeco/Dometic compressor fridges are notorious for being votlage sensitive, the factory installation literature and their website comes with warnings about using suitably sized cable to avoid a voltage drop and the later ones have a sensitivity setting.
Had the same problem with our CFX345 last weekend, plugged into an outlet that says max 15A but when I checked the size of the cables (and the state of the terminals: green!) it was no wonder that it only saw 13+volts with the engine running.
I sold a massive CF110 years ago with a suspected thermistor fault, even supplied it with a spare but had no time to replace it.

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Robsey
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Re: Dometic CRX Fridge not cooling - FIXED!!

Post by Robsey »

silverbullet wrote: 04 Aug 2022, 07:17 Waeco/Dometic compressor fridges are notorious for being votlage sensitive, the factory installation literature and their website comes with warnings about using suitably sized cable to avoid a voltage drop

This is something I found out quite quickly after a fair few hours googling and trying to find non-existant youtube videos to fix the temperature sensor fault.

Hence, why I posted this thread up. First to find advice... and latterly to save people from having to search like I did.
1983 Tin Top with a poorly DF and 4 speed DT box.
1987 Electrics and a DJ engine.
Maybe one day I might get it finished

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