Now need help with 12V fridge problem please

Submitted: Saturday, Jan 10, 2009 at 16:09
ThreadID: 64989 Views:2151 Replies:5 FollowUps:8
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Hi all,

Well we hooked up the 12v for the 3 way fridge so we can travel safely - We are not 100% sure we have done it correctly - the circuit breaker is clicking (its a 20amp) and the power at the trailer plug is 14V with no load and 0V with load. Is this correct or have we done something wrong?

Thanks in advance for any help

Cheers
Matt, Caz & kids
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Reply By: Tenpounder - Saturday, Jan 10, 2009 at 16:53

Saturday, Jan 10, 2009 at 16:53
Hi there. Sounds like a dead short in the 12 v wiring. Had the same thing a while back. The only solution I know is to systematically test the circuit. In my case, everthing tested OK right through to the fridge itself, and the fault was in the 12 v heating element within the fridge (about $200 to have replaced).
It depends how handy you are as to whether it is a DYI job. There may be a 12 v plug and socket somewhere inside the van, and near the fridge. If so, unplug that, and try again: if you still have say 12.5V or better at the socket, then it is probably in the lead to the fridge, or in the fridge itself. If it does not make a difference (ie if the socket does not give you a 12V or better reading) then the short is probably between the drawbar connector and the kitchen of the van.
Does this help?
AnswerID: 343587

Reply By: Member - Garth J (NSW) - Saturday, Jan 10, 2009 at 16:55

Saturday, Jan 10, 2009 at 16:55
Matt,

Not much to go on but......

14v open circuit at the plug seems ok.

Is the c/b only clicking when trailer is plugged into the car?

The noise is the c/b open circuiting. To protect the downstream wiring.

I suspect you have a short circuit when plugged in. And most probably active(+ve) and neutral (-ve) are maybe reversed on the trailer end.

Or you have a s/c to earth(trailer) body of the positive wire.

Hope this is some help.

Garth
AnswerID: 343589

Reply By: Topcat (WA) - Saturday, Jan 10, 2009 at 16:56

Saturday, Jan 10, 2009 at 16:56
Hi Matt, it sounds like to me that you are using to small a cable size wiring to carry the necessary current load to operate the fridge. This will cause the circuit breaker to cut in & out because there is not enough current to fully connect it. The heating coil in 3 way fridges usually draw a lot of current ( some up to 10 amps) & because it is situated in the trailer I assume it is some distance from the supply battery.
I would suggest you use a minimum cable size of 6mm rated for 25 amps to supply the necessary load current. Hope this helps explain your possible problem. Cheers.
AnswerID: 343590

Follow Up By: Topcat (WA) - Saturday, Jan 10, 2009 at 17:04

Saturday, Jan 10, 2009 at 17:04
I also agree with the other post comments that there is a possible short circuit somewhere in the wiring. Cheers.
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FollowupID: 611426

Follow Up By: Member - Garth J (NSW) - Saturday, Jan 10, 2009 at 17:13

Saturday, Jan 10, 2009 at 17:13
Topcat,


I'm an electrician and the following sentence puzzles me.....

"This will cause the circuit breaker to cut in & out because there is not enough current to fully connect it."

Small cable size will result in voltage drop at high currents.
The c/b is designed, rated and used to protect the cable from melting caused by overcurrent.

The c/b is the "weakest link" The c/b is usually rated less or equal to the current carrying capacity of the cable.

The cable can carry infinite current (theoretically) but will overheat and melt in a very short time (read milliseconds) if the current is too high.

Sorry I'll get down now.....

Cheers
Garth
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FollowupID: 611427

Follow Up By: kev.h - Saturday, Jan 10, 2009 at 18:33

Saturday, Jan 10, 2009 at 18:33
Hi garth
Sounds like topcat may be thinking of a relay have had them do that with a short when the circuit voltage drops
Kev
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FollowupID: 611436

Follow Up By: Topcat (WA) - Saturday, Jan 10, 2009 at 19:58

Saturday, Jan 10, 2009 at 19:58
Hi Garth, you are correct. I was thinking as Kev mentioned of a relay then realised after I submitted the post that the circuit breaker is designed to do just what it says- break the circuit incase of a short. No need to apologise. I stand corrected. We all learn from our mistakes. Cheers.
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FollowupID: 611443

Reply By: Member - Old Girl (QLD) - Saturday, Jan 10, 2009 at 19:25

Saturday, Jan 10, 2009 at 19:25
Caz,
How did you get on at trailavan in Toowoomba.
Sharon
AnswerID: 343610

Follow Up By: Member - Matt & Caz H (QLD) - Sunday, Jan 11, 2009 at 16:31

Sunday, Jan 11, 2009 at 16:31
Hey Sharon,

Really well, the AC was fixed ASAP - recommend them highly!!!! We are now in Dubbo and have just come back from the WesternPlains Zoo - the girls loved it - we will stay in Dubbo for a day or so because now the toilet wont flush................................. Want doesn't kill you makes you stronger hey????

Cheers
Caz
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FollowupID: 611537

Follow Up By: Member - Old Girl (QLD) - Sunday, Jan 11, 2009 at 18:29

Sunday, Jan 11, 2009 at 18:29
bleep hey !!!!!!
Well I believe things happen in threes and you have had it. At least you still have warranty. Whats your plans next.
Sharon
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FollowupID: 611567

Follow Up By: Member - Matt & Caz H (QLD) - Monday, Jan 12, 2009 at 11:03

Monday, Jan 12, 2009 at 11:03
Actually its the 4th thing but hey whos counting.............. 1/ Fridge, 2/Gas issues - replaced both bottles and lines flushed, 3/ A/C, 4th Toilet - there ISNT going to be a 5th!!!!!

We are staying in Dubbo for a few days - the van is having its 1st service tomorrow (3mth warranty thing.) - Then we are heading towards Ballarat - Matt has applied for a job down there so we will set up camp for a few months and build up the kitty.

Cheers
Caz
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FollowupID: 611701

Reply By: Al-one - Saturday, Jan 10, 2009 at 23:01

Saturday, Jan 10, 2009 at 23:01
Matt,
I am an electrician and believe that you have a short circuit in either the wiring to the fridge or in the fridge element. I had the same problem and it turned out to be the positive wire to he element had shorted to the element housing close to the actual element . It was caused by the thousands ok kilometers of corrogations travelled over in the van over the years. It was a relatively simple job of re-insulating the lead and suporting it so the same thing wouldn't happen again. I had to take the fridge out to get at the element though.
Cheers,
Al-one
AnswerID: 343637

Follow Up By: Member - Matt & Caz H (QLD) - Sunday, Jan 11, 2009 at 16:29

Sunday, Jan 11, 2009 at 16:29
Hi all,

Thanks so much for all your help and suggestions - turns out the GUMBY who wired the trailer plug on the van at the RV place had 2 wires round the wrong way. I have now rectified the problem and all is working well.

Thanks once again!!!

Cheers
Matt Caz & Kids
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FollowupID: 611536

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