crob Posted November 4, 2014 Share Posted November 4, 2014 Here I go again with a tricky problem. A Hymer S class built 2002. Under the bonnet next to the battery is a fuse holder containing a red 50 amp fuse & in front of that, a green 30 amp fuse. The green fuse keeps blowing - the plastic is melting. I have tried several fuses & they all end up the same. It's difficult to tell whether it is blowing at once or after an hour or two of running. This fuse controls the fridge on 12v, the control panel switch that shows the battery level of the engine battery, & maybe other things that I don't know of. The fridge works fine on 240v & gas. The control panel switch showing the battery level of the habitation batteries ( same rocker switch as engine battery) works fine. It may be that something in the fridge 12v circuit is shorting. If so I think this may involve removing the fridge - time consuming & therefore expensive. I've tried Lowdhams but they weren't that helpful. I don't think that Mercedes could help as it's Hymer related. Maybe an auto electrician would know? Any ideas anyone? Link to comment Share on other sites More sharing options...
sshortcircuit Posted November 4, 2014 Share Posted November 4, 2014 Similar problem and replaced fuseholder and fuse with good quality units and had no further problems. Unless you can identify a fault its worth a try. Reread and as fuse is melting plastic this is definitely worth a try, poor contacts. Link to comment Share on other sites More sharing options...
Tracker Posted November 4, 2014 Share Posted November 4, 2014 Poor contacts sounds favourite to me as that is what is creating the high resistance that causes the overheating and it's overheating that can blow a fuse not just power overload. Try something like a cut down emery board to deep clean the contacts with the fuse out. I suspect what you have might be a relay rather than a fuse holder and if so also look underneath as the cable contacts entering the unit might also be dirty or corroded or loose? If it is just a fuse holder I would replace it anyway if only to rule out further problems but a relay is not as inexpensive as a fuse holder but if all else fails you might have to replace it rather than risk unreliability? Link to comment Share on other sites More sharing options...
Brambles Posted November 5, 2014 Share Posted November 5, 2014 Check your leisure batteries, they may have too high a charge rate as they are faulty and possibly on same circuit. Link to comment Share on other sites More sharing options...
StuartO Posted November 5, 2014 Share Posted November 5, 2014 crob - 2014-11-04 8:16 PM Here I go again with a tricky problem. A Hymer S class built 2002. Under the bonnet next to the battery is a fuse holder containing a red 50 amp fuse & in front of that, a green 30 amp fuse. The green fuse keeps blowing - the plastic is melting. I have tried several fuses & they all end up the same. It's difficult to tell whether it is blowing at once or after an hour or two of running. This fuse controls the fridge on 12v, the control panel switch that shows the battery level of the engine battery, & maybe other things that I don't know of. The fridge works fine on 240v & gas. The control panel switch showing the battery level of the habitation batteries ( same rocker switch as engine battery) works fine. It may be that something in the fridge 12v circuit is shorting. If so I think this may involve removing the fridge - time consuming & therefore expensive. I've tried Lowdhams but they weren't that helpful. I don't think that Mercedes could help as it's Hymer related. Maybe an auto electrician would know? Any ideas anyone? It's a great pity that Hymer don't pblish a habitation woring diagram with their Owner's Manual, but they are reasonably helpful if you ask for tchnical help - although they are not quick. Maybe by following the cable routing from the fuse box you could find where to disconnect the 12 volt supply to the fridge without taking the fridge out, so see if that allows the fuse to be replaced without blowing. The cable should be thick stiff, 35 amp rated, but then divide into sub-circuits at some point. This 30 amp fuse protects that 35 amp cable circuit and probably serves more than just the 12 v fridge, so maybe you need to work out what else it supplies with power in order to check those sub-circuits for faults. Is the Electroblok still getting a 12 volts supply from the engine's alternator when the engine is running? It would clearly be dangerous to continue to keep replacing the fuse without finding the fault. If in doubt get an autoelectrician to look at it. These people know a lot about Schaudt Electrobloks: http://www.atlanticmotorhomeservices.co.uk/ Link to comment Share on other sites More sharing options...
crob Posted November 13, 2014 Author Share Posted November 13, 2014 Thankyee all. Have had new fuse holder fitted and all works. The real test will come after 2-3 hours running. But it looks good. Link to comment Share on other sites More sharing options...
sshortcircuit Posted November 13, 2014 Share Posted November 13, 2014 Thank you for providing feedback, which sadly few do. Hopefully your problem has been resolved. (lol) Link to comment Share on other sites More sharing options...
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