Electrical Fridge

Jenicecu

New Member
Mar 31, 2018
5
0
1
Whyalla s.a.
#1
Have a domestic rm2350 3 way fridge. The wire that is connected to the fridge fins is hanging down a bit by the drip tray. Does it go up behind the fins for better temperature control.it is a bit rusty so can I just give it a light rub with sandpaper.thanks.
 

Boots in Action

Well-Known Member
Mar 13, 2017
649
627
93
Ferny Grove, Queensland
#2
Have a domestic rm2350 3 way fridge. The wire that is connected to the fridge fins is hanging down a bit by the drip tray. Does it go up behind the fins for better temperature control.it is a bit rusty so can I just give it a light rub with sandpaper.thanks.
Hi @Jenicecu and welcome to the forum. Lots of info on here and a lot of experienced members too. I don't like the sound of a loose wire hanging down at the back of fridge. Normally there is no wire connected to fins at the back unless it is an earth wire for the 240v line, but usually that earth wire is connected to a better point lower down. Do you have any fans connected to the back of fridge or something similar? If so it could be one of the wires from a thermostat for the external fan. If hanging down near the drip tray but still connected to the fins at the top, it could be some sort of sensor for something. You will have to provide more info or pictures so correct info can be given. Is it a single wire or twin and how is it connected to the cooling fins?? If you remove the top vent, you might be able to see a bit more of what is connected. Here is a picture of a thermostat for cooling fans that I have in my van where a wire may have come from.
 

Attachments

Jenicecu

New Member
Mar 31, 2018
5
0
1
Whyalla s.a.
#4
Thanks, it is inside fridge and is temp sensor apparently. Been sorting out why fridge not working on 12 volt while driving.had dedicated line fed to Anderson plug on car. Put in Karl's Koop fans on vents and one in fridge. They work great.got fridge cold on 240. Yesterday put fridge on 12v to do some testing with batteries. Discovered that it had no power to Anderson. New cord reads on gas / 240. Heater tube stopped getting hot and fridge temp dropped. So i think after some more volt testing that I need a new heater 12v tube thing.
 

Boots in Action

Well-Known Member
Mar 13, 2017
649
627
93
Ferny Grove, Queensland
#5
Thanks, it is inside fridge and is temp sensor apparently. Been sorting out why fridge not working on 12 volt while driving.had dedicated line fed to Anderson plug on car. Put in Karl's Koop fans on vents and one in fridge. They work great.got fridge cold on 240. Yesterday put fridge on 12v to do some testing with batteries. Discovered that it had no power to Anderson. New cord reads on gas / 240. Heater tube stopped getting hot and fridge temp dropped. So i think after some more volt testing that I need a new heater 12v tube thing.
@Jenicecu , you can put your multimeter across the terminals for the 12 volt fridge where wires from van plug attach to rear of fridge. There should be a resistance of around 0.9 ohms if element is approx 160 watts. You should also check that voltage from tug or from any other 12 volt source is ACTUALLY getting to that connection at back of fridge, accessible by removing bottom vent. To replace 12 volt element is costly (approx $80.00 or $90.00 I think) and there is a lot of work to replace the heating element, besides removing fridge from van. Make sure it is not a wiring problem etc and save yourself a lot of work. Good luck.
 
Last edited:
Likes: Jenicecu

mikerezny

Well-Known Member
Sep 11, 2016
786
1,406
93
65
Mount Waverley, VIC
#7
There should be a resistance of around 13 to 15 to ohms if element is approx 160 watts.
Hi @Boots in Action,
I think your maths is incorrect. P = V*V/R. Therefore R = V*V/P. In your example, V = 12V and P = 160W. Feeding that into a calculator give a resistance of 0.9 Ohms.

Quick and dirty method: 1 Ohm across 12V would draw 12A. Power consumed would be 12A * 12V = 144W. So 160W would need a lower resistance. The difference of 144W to 160W is about 10%, so reduce 1 Ohm to 0.9 Ohm would dissipate approximately 160W.

So, one would expect a reading of about 0.9 Ohm across a good 12V 160W element, not 13-15 Ohms.

cheers
Mike
 

Boots in Action

Well-Known Member
Mar 13, 2017
649
627
93
Ferny Grove, Queensland
#8
Hi @Boots in Action,
I think your maths is incorrect. P = V*V/R. Therefore R = V*V/P. In your example, V = 12V and P = 160W. Feeding that into a calculator give a resistance of 0.9 Ohms.

Quick and dirty method: 1 Ohm across 12V would draw 12A. Power consumed would be 12A * 12V = 144W. So 160W would need a lower resistance. The difference of 144W to 160W is about 10%, so reduce 1 Ohm to 0.9 Ohm would dissipate approximately 160W.

So, one would expect a reading of about 0.9 Ohm across a good 12V 160W element, not 13-15 Ohms.

cheers
Mike
Yes @mikerezny , bluddy Ohms Law has caught me out once more!! What I came up with was current draw in AMPs of course!! You are correct - very low resistance for element needed to get that hot. So back to school for me. Thanks for picking that up - again!!! Damn it!!!!!!
 
Likes: Jenicecu

Drover

Well-Known Member
Nov 7, 2013
7,317
13,470
113
Cooloola Coast, QLD
www.expandasdownunder.com
#9
:clock:
Hi @Boots in Action,
I think your maths is incorrect. P = V*V/R. Therefore R = V*V/P. In your example, V = 12V and P = 160W. Feeding that into a calculator give a resistance of 0.9 Ohms.

Quick and dirty method: 1 Ohm across 12V would draw 12A. Power consumed would be 12A * 12V = 144W. So 160W would need a lower resistance. The difference of 144W to 160W is about 10%, so reduce 1 Ohm to 0.9 Ohm would dissipate approximately 160W.

So, one would expect a reading of about 0.9 Ohm across a good 12V 160W element, not 13-15 Ohms.

cheers
Mike
AaaaaRrrrrrrrGggggggHhhhhhhhh. o_O:oo_O


Migraine coming on.........


Yes @mikerezny , bluddy Ohms Law has caught me out once more!! What I came up with was current draw in AMPs of course!! You are correct - very low resistance for element needed to get that hot. So back to school for me. Thanks for picking that up - again!!! Damn it!!!!!!
 
Likes: Crusty181

Jenicecu

New Member
Mar 31, 2018
5
0
1
Whyalla s.a.
#11
Thanks guys,will pass info to electrician son in law. Heating element about $170. Now. Reading other post about setec ect,we are getting a better understanding of the muddle at back of fridge.and how Setec works and wiring size
 

Boots in Action

Well-Known Member
Mar 13, 2017
649
627
93
Ferny Grove, Queensland
#13
Thanks guys,will pass info to electrician son in law. Heating element about $170. Now. Reading other post about setec ect,we are getting a better understanding of the muddle at back of fridge.and how Setec works and wiring size
Hello there again @Jenicecu , I think you will find that the price I gave you for a heating element for your Dometic 3 way fridge was about right. I was shocked at the price you are working on. Have a look on Ebay at the site listed below where you can get the Genuine article for only $90.00 instead of the $170.00 you are looking at.

https://www.ebay.com.au/itm/12v-Ele...558?epid=728680600&hash=item4d6c49b4e6:g:h~UA
If the worst come to the worst and the element has to be replaced, don't pay the dearer price when a much lower price is available. I will also refer you to a previous post of mine involving the overhaul of a friend's fridge of the same model , when I find the post number. You will find it interesting reading as I came across a similar problem with his 12 volt heater for the fridge. More to come and good luck too.
 
Likes: Jenicecu