Electrical Dometic Fridge - 12v operation

[Drover]

Righto putting the call out hoping someone can assist.....My 3 way Dometic fridge is one that has the auto start AES set up, works fine on gas and 240 but can't get it to switch to 12v, no problem with 12v supply as far as the relay but unable to get the fridge to recognise 12v supply from vehicle so it will activate 12v fridge setting. Even hot wired the element to make sure it worked.

Circuit diagram isn't much help but I was wondering if anyone knew what the D+ wire from circuit board connects to, mine disappears into the wall .
As far as I can tell there is no connection between 12v supply from tug and fridge other than the relay before the heater elements, I have cross checked on another van the same and the tug power runs direct to frdige and while the 12v worked on it can't figure out why not on mine, even changed the relay to no avail, something is amiss......tracked everything with the meter and same , same so suspect the board .

While it's not important as 12v is basically useless on the fridge I thought I may be on a win after I successfully got my Son in Laws fridge to run on gas after sorting the thermocouple out it all came good, saving him mucho $$$$$$ but as always it all comes together when doing something on other peoples gear mine always gives me curry....

 

[Dobbie]

I'd love to be able to offer a suggestion but it's well beyond me.

If you don't really want to use the 12v feed from the Colorado, is it more a problem solving conundrum for you rather than a real need to get the 12v?

Either way, I can see where you're coming from ....but where you go is possibly to a dometic parts store.

 

[millers]

Do not know if you have this document or whether it helps, but gives the options for AES wiring.

 

[Drover]

Thank you @millers thats just what I've been looking for, it confirms my suspicion and I can only suspect the cable from the D+ point must run to join up with the old fridge 12v wiring from the tug socket, this was by passed for a direct 12v feed using anderson plugs.........................I just didn't want to shunt power down this wire and blow the board or something...........................5min job to get it up and running I think, and yes @Dobbie If there's ever a problem I have to solve it, well with my vehicles anyway, if it don't work, no matter if I ever use it I prefer it to work......unless it requires the dashboard to be removed then I can live with it, hate dashboards with a passion.....................

Now before I crow anymore, where's my screwdriver ?????????????

Did a big search and believe me there are some wankers on other sites..................................

 

[achjimmy]

Our dometic and this thetford work really well on 12v actually the dometic would freeze down on 12v you just had to make sure it was getting all the voltage available? (I ran 13mm sq right through )

 

[Drover]

Well thats done and dusted............................fridge now works on 12v and I better get a relay set up so it only works when engine running.....actually if I connect the D+ wire to the side lights there's my fridge switch
Thanks again @millers I didn't turn up that info on any of the searches I have done..........

Yes @achjimmy the cable used on Big Mal is bloody huge, a tight fit into the anderson plugs actually so size is good but the actual wires on the element get flamin hot

 

[Dobbie]

I love successful outcomes, particularly if they're quick.

(and I managed to get one of my lawn mowers working...very pleased with myself...so it's only two to be disposed of...and I also managed to finish some aluminium trimming in the kitchen. Found it in the shed and put it to the use it was acquired for, but forgotten)

A lucky find from @millers ....it just shows this forum is more productive.

 

[Drover]

It makes a nice change to be the receiver of great info @Dobbie and if you get up here at any time I have a Honda brush cutter thats carbie needs a good service, hang it up in shed for about 6 mths, fill it with fuel and runs like a beauty until you stop it then dead as Dodo, strip carbie down put back together and all good till next shut down........more than likely need new gaskets all round, been on the To Do list since it shut down day before daughters wedding, so raced out and bought a new one, we had tight deadlines and I thought have 2 brush cutters running, wow, one with a cord job and other with blade to chew up the lantana..................lets see daughter has been married for 8 yrs now, some things take time, at least no lantana to worry about, wonder if I could put a propeller on it for the yak..???

Off Topic again, well problem solved, enjoy.

 

[Dobbie]

Off topic is contagious!

Speaking of which, I've got two brush cutters needing some attention as well.

They're in the other shed so will not strain my attention span in the immediate future!

Maybe I'll label them 'Wait Awhile'....

 

[dagree]

Maybe I'll label them 'Wait Awhile'....

Got enough of them over here...

 

[Drover]

It will be interesting to see how it all runs on 12v next trip, I wonder if it's possible to upgrade the cable from fridge junction to elements, they all say to use 6 or 8 BS cable but the stuff they use for the elements isn't and gets very hot.

 

[dagree]

I wonder if it's possible to upgrade the cable from fridge junction to elements

I am sure you will find a way @Drover and expecting a post when you do

 

[Drover]

In the fullness of time and all that, maybe but probably not, trying to figure out a way to set up my fridge switch relay without doing a lot of stuffing around, if I could just find a tail light wire thats handy to hook the D+ wire to I would be sweet but the Coromal unlike Jayco have all the wires buried in the wall or chassis rail.
I know that relying on turning fridge off or pulling the plug at stops is not a very good idea, fraught with danger and if I had it running from the Aux Battery in back of truck the Engel and van fridge would draw more than my little panels could keep up with and my beer might get warm.........

 

[chartrock]

Mate, just run a pair of heavy duty wires direct from your main battery via an ignition relay to an anderson plug. Engine off, fridge off, no problems.

 

[Drover]

Mate, just run a pair of heavy duty wires direct from your main battery via an ignition relay to an anderson plug. Engine off, fridge off, no problems.

The cable run is already there and that is one of the options, set a relay up at the circuit breaker I have near the battery just looking for the easiest plus prefer it on the van..................in time, in time.

 

[millers]

You may wish to consider it being on the car rather than the van. Understand that you may tow with lights on so it will be off when not towing, however if you are on a narrow road parked (having a meal in the pub) you may want to leave your lights on meaning you are running your battery down. To my mind it is always better to protect at the source. If you have to tow any other van (or trailer needing power) that does not have the same setup then you will end up with a flat battery if you do not remember (although rare). Depending on where the battery is there should be an ignition source close by that you can plug into to run the relay.

If you need the option of leaving it on then add a bypass Switch that you can toggle to allow power through the Anderson if the ignition is turned off.

And in my over engineering state you could also make the bypass a latch type that when you turn the ignition on would deactivate the bypass so it only bypasses once, so you do not have to remember to turn the bypass off. But you need to look at this being worth it.

Cheers
Steve

 

[Drover]

All good points @millers , on my old rig I just had a relay at the back of the fridge and since the clearance light wires where running along the floor there I just hooked up to them and in all the trips I did, the chimes saying my lights were on never failed me but I never came across the situation of leaving my parkers on for some reason, good point.
So since I like to cover all options I may go with the relay under the bonnet only a 5 min job.

 

[ROnEM]

Option 3 or 4 looks the best with a fridge movement switch. Install at the base of the fridge where all the other wiring is present. Keeps it simple and consistent - don't have to play with the vehicle wiring.

Off-Topic - I always use the Briggs & Stratton Fuel Preserver additive in all my petrol motors - ride-on mower, chainsaw, generator, push mower, fire pumps, line trimmers, etc. Stops the fuel going stale, stops the gum building up too in the carbie. Have had the Victor pull start push mower for 16+ years, only gets used a few times a year and starts every time, usually first time!!