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urgent help / advice please

2K views 10 replies 7 participants last post by  cabby 
#1 · (Edited)
urgent help / advice please dometic fridge freezer blowing 12v fuses

Just left for an extended foreign trip and our fridge is not working on 12v (tall Dometic with digital display and separate fridge / freezer).

It has always worked fine in the past on 12v, but tonight, as soon as the engine is started it blows the fuse (7.5a standard fuse, replaced and blown again, then blew another 2x 10a fuses whilst I was trying to find a way around it).

I'm struggling for internet, struggling with the new site on a mobile device and stressing as I have no handbooks with me (I do have a multimeter though). Any suggestions or help would be VERY MUCH APPRECIATED.

(Is 7.5a the correct rating as it seems low to me?)
 
#3 ·
That seems a VERY low rating for a fridge freezer to me, hopefully someone will be along shortly with a similar unit and a definitive answer.

Not working on 12 volts is the least worst problem scenario as that's ONLY when you are driving. As long as you don't keep opening the freezer part everything will stay cool for many hours, by which time you will probably have stopped and be back on either gas or EHU, and probably overnight at least?

So it's not that serious a problem really, annoying maybe, but not something to get stressed over.

Andy
 
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#4 · (Edited)
Don't know what size of fuse - should be in your handbook. Take the bottom vent off to gain access to the rear of the fridge and check the tightness of all of the wires where they come into the connector blocks - you may find one (or more) loose/not tight. Give them a little tug. You could slacken one off at a time and pull the end out from the terminal block and you should see where the screw was pinching it - you may find a bit of outer cable stopping a good connection. Should only take a few minutes and no cost. When all checked put in new fuse and give it a try.
I had my fridge fuse and holder burn out a few years ago (two fuses and holders adjacent to the battery under cab floor both burnt out). Found a couple of wires not clamped tight behind fridge. Tightened up and never had any further problems. I don't think that the screws had worked loose, just had not been fully tightened at manufacture.
DavidL

Just noticed that you haven't got your handbooks with you. Always replace like for like ie if it's been ok on 7.5a fuse up to now then replace with same. You need to get to bottom of why it's burning out - hence checking the connections. I think that my fuses were 10a (but may have been 7.5a) and a 25a or 50a.
 
#5 · (Edited)
Basically if it is an instant fuse blow it is a short, if slow it could be a loose connection. Am I not right in saying there should be 2x 12v supplies to the fridge, one for supply whilst engine running and the other for ignition when on gas.
Have you checked the connection on the relay end, has any job or anything been done under the bonnet recently.could it be too fast over a speed hump jolted the cables at the back of the fridge.There should be 2 connector blocks with 12v.
take a deep breathe and look at it logically.while the boss makes a cup of tea/cocoa. or put it on gas/230v and look in the morning.

cabby

edit. will try and find he wiring diagram that was posted earlier. Found it, hope this helps.
http://data.manualslib.com/pdf3/72/...m_7655_l.pdf?30c30b65ba4c48bce4981e524abd64b4
 
#7 ·
A bit more info. Fridge is a Thetford n145.

Fuse for fridge as per manual is in the garage and its OK (20A). The fuse that keeps blowing is actually in the cab and is for the electric mirrors, but is in someway linked as this is what is taking the fridge out.

I think there are also relays in there but its a complicated set up as its an a class and the bits are hard to get to and are hidden behind this small 4 fuse, fusebox that keeps blowing.

Any ideas?
 
#10 ·
A bit more info. Fridge is a Thetford n145.

Fuse for fridge as per manual is in the garage and its OK (20A). The fuse that keeps blowing is actually in the cab and is for the electric mirrors, but is in someway linked as this is what is taking the fridge out.

I think there are also relays in there but its a complicated set up as its an a class and the bits are hard to get to and are hidden behind this small 4 fuse, fusebox that keeps blowing. Any ideas?
Yes 20 amp sound right for a 12 volt fridge.
Very difficult to attempt to diagnose why the other 7.5 amp fuse is blowing. Is it the 12v. supply to the electronic control board. If so stay on gas or 240v. As a new 'board' will be expensive and probably need to be ordered.

Just my 2p worth.

Ray.
 
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#9 ·
Having had a few fridge probs in the past what I would first do is open the lower fridge vent on the out side of the van and locate the 12 volt heater , it looks like a L shaped 10mm rod that goes in the big tube on the right , there are two of these one for 240 v and the other is 12 v disconnect the 12 volt one and replace the fuse that blown switch it all on and see if it still blows the fuse, if it's ok then you know that your problem ,
If not then I have no idea, strange that it's, it's all connected to your mirrors . Dennis
 
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