17' Series DC on the fridge not working efficiently

[Matthew keough]

Hi all,
Have a small issue with my fridge while running DC. It is either not working or im doing something wrong. Rang Jayco Melbourne head office. They were good, unfortunately as its a warranty thing I've had to contact dometic. I've got the 120l in a 17.56. Has anyone else had issues.

 

[mfexpanda]

They don't work real good on 12v more to maintain the temp while driving than using all the time

 

[marty18576]

Is your car wired for DC.? Some people just assume its a autolec job.

 

[Matthew keough]

Is your car wired for DC.?

Had the Hotwire done when we got the van. Did a 3 week trip in it back in October didn't notice it defrosting, but im not sure now because it was always full with frozen stuff. Had a few little trips recently and had issues

 

[Bellbirdweb]

Over Christmas we used 12v for the first time on long trips.

On the fist day we noticed the fridge had climbed from -1 to 9 degrees over 8 hours.

I put a multimeter across the 12v contacts at the fridge and there was no voltage there.

Opened up the 12 pin plug and found the +ve wire to the fridge was on the wrong terminal.

I moved it to the correct terminal and then had 12v at the fridge.

Over the remainder of the trip, it was still warming several degrees whilst we were on the road, but in general it seemed to be doing a little bit of cooling.

We also found that we often parked in towns to have a look around, and the parking spots were rarely ever level, so it would be pulling 18A but not cooling as the fridge wasn't level.

Basically the 3 ways are pretty crap on 12v.

 

[Drover]

I have found if I have my fridge chilled down the 12v will keep it at temp but won't pull down the temp, you have to make sure with the wiring that you have decent cable on the tug side for the power draw, I also refitted the bunch of **** that was the major junction of wires from tug to van, the connections were a bit crappy and fitted a 30amp relay to my fridge power which is activated when I turn the parkers on , so when I'm driving the fridge runs but when I stop in town and turn the parkers off the tug battery stays good, otherwise it would be flat in 45 mins. If you have a seperate battery good stuff but unless you have an Engel you must be level or the fridge won't work, I have found that mine will hold temp for a couple of hours when not running but your fridge and the stuff in it needs to be down to temp.

 

[AndrewC]

Few things that I have found.

1. Jayco's wiring is undersized for a 12v element.

2. The route lengh that they ran it in my 17.56-2 was way too long for that size as it went right down the length of the van, across the back and then back up the other side to the fridge.

I rewired mine with a shorter length and a heavier wire which helped marginally but by default, the system is not real efficent. There is no thermostat control on it simply because it does not need it as it will never get the fridge any cooler then the temp it is at when you disconnect power 240v power or gas. At best, it aims to maintain temp but generally it can't even do that.

What is the solution, not real sure apart from getting a compressor fridge which is what I did eventually

 

[Drover]

It is a whole of concept thing, if the fridge is fitted correctly or not. Most I have seen are not fitted correctly so thats the start of the problem, fix that and 12v works as it's supposed to and thats to maintain temp, it will not pull down a fridge from 22 to 4 deg inside a week or so.
If you want 12v to support a fridge/freezer all the time then you need an Engel the only fridge that will work on 12v efficiently and will work at angles that if are increased the fridge is not your problem as you vehicle has fell over.
Mine has been operating since 1978 and while battered is still working like a new bugga.

 

[dagree]

Might be a silly question @Matthew keough ..... But is the selector switch in the right position?
Have forgotten to switch it over more than once myself

 

[Hubble80]

I found our 150L in our 17.56-2OB worked really well on 12V to maintain temp. Saying that, it has been rewired with a lot larger cable to an Anderson plug. I only lose 0.02V at the terminal strip in the back of the fridge. The cable is well and truly suited to carry the 15A that distance!

 

[achjimmy]

We had the 150l Dometic in the expanda. I wired from the tug to an Anderson in 13mmsq wire (6b&s) then from the Anderson to a self resetting fuse at the fridge again in 13mmsq. The 100mm from the self resetting fuse to the fridge terminal was in 6mm auto (4.5mm sq) with a blade fuse. Damn thing would pull down to below zero over a drive. Worked a treat. Jayco's wiring is inadequate, read the Dometic or thetford install manual then ask jayco how they can use such small gauge wire in face of the manual?

Upgrade the wiring if you need it to perform on 12v

Fyi. I have found the Thetford performs better on 12v than the Dometic.