Jiving Jeff Posted April 9, 2020 Share Posted April 9, 2020 I need to find the relay and/or fuse for the 12v fridge supply in my Bessacarr Ducato 2002 version. The Dometic 7271 fridge onboard fuse is OK, new heater elements are installed but 12v will not work when engine is running. Link to comment Share on other sites More sharing options...
Alanb Posted April 9, 2020 Share Posted April 9, 2020 Hi, 1. Does the fridge work on gas and 240V? This would confirm the presence of the permanent 12V control supply. 2. On Ducato based vehicles of the stated age, both split charge and fridge relays are often located under the plastic hood at the rear centre of the engine bay. You should also expect to find an upto 50A inline fuse for the split charging, and a 20A fuse for the fridge Given the age of your vehicle, it is possible that some corrosion of fuse or relay terminals could occur in this area. Please note that the split charge relay has both habitation and starter batteries connected to its contact terminals. Do take the precaution of removing both battery negative leads before removing any connections on the relays. The split charge relay is somtimes powered in parallel with the fridge. This is good practice, as it avoids draining a double ration of power from the initial excitation of the alternator. Alan Link to comment Share on other sites More sharing options...
BruceM Posted April 9, 2020 Share Posted April 9, 2020 Which make and model of habitation control electronics is used on the Bessacarr Ducato 2002 ? Link to comment Share on other sites More sharing options...
Jiving Jeff Posted April 9, 2020 Author Share Posted April 9, 2020 Cheers Alan, It seems that a permanent 12v supply is present. I've located three relays undre the hood removed them and checked that the solenoids function. Found and replaced a blown 20a fuse. Will now look for corrosion problems. Apart from connecting to as seperate 12v supply, Is there a simple way of checking the new 12v element using a multimeter ? Jeff Link to comment Share on other sites More sharing options...
Jiving Jeff Posted April 9, 2020 Author Share Posted April 9, 2020 Sorry, no idea, just looks a simple basic setup, nothing like the modern systems. Link to comment Share on other sites More sharing options...
Alanb Posted April 9, 2020 Share Posted April 9, 2020 Jiving Jeff - 2020-04-09 4:32 PM Cheers Alan, It seems that a permanent 12v supply is present. I've located three relays undre the hood removed them and checked that the solenoids function. Found and replaced a blown 20a fuse. Will now look for corrosion problems. Apart from connecting to as seperate 12v supply, Is there a simple way of checking the new 12v element using a multimeter ? Jeff I am not sure what the third relay is for. If it looks different it could be original Fiat for either the thermal starter or the heat flange as appropriate. If added by the converter, it could be for an electric step, but then not in the optimum position for wiring. The 12V element is rated at 130W, presumably at 12V. This indicates a resistance of 1.1 Ohms. If you can access the wire leading to the element you should at least be able to check for continuity, but the resistance of the meter leads will be significant if trying to measure such a low resistance. You could try measuring the meter leads on their own, and then subtracting from the total. It is my understanding that in the Dometic 7xxx range of fridges, the 12V element is thermostatically controlled. (See Dometic manual page 6 or 7, clauses 5.2.1, or 5.2.2 as appropriate.) This involves a second relay in the fridge control panel. I remember that Robinhood who is a frequent contributor to this forum, has replaced the integral control panel relay on a friends MH. If you can find the thread, perhaps via Google, it may help. Alan Link to comment Share on other sites More sharing options...
Robinhood Posted April 9, 2020 Share Posted April 9, 2020 ..I'm not sure that my experience of fixing an AES fridge is going to help you here. You're not clear where you found the three relays, but if they were all in the location under the cover as pointed to above, then I would expect to find only two relays (*with a fridge). *Nonetheless, the wiring diagram from 2003/4 does show a third relay when a fridge/freezer is fitted. Interestingly enough, it also shows an additional fuse in this case. It just might be worth a hunt for this. (It is unlikely to be in the fuse unit next to the relays, where I suspect you might have found your blown fuse). Diagram (for both fridge and fridge/freezer) can be downloaded here (and I doubt there was much, if any, variance between yours and this slightly later version). https://sargentltd.co.uk/tech-support/article/25/download/253 (This is the earliest one I can find) Link to comment Share on other sites More sharing options...
Jiving Jeff Posted April 10, 2020 Author Share Posted April 10, 2020 Many thanks for your help Alan and RobinHood. I have located the step relay which is located near the step switch inside the fridge compartment. I isolated the heater elelment and got a resistance reading of 1.3 Ohms. I then wired it to a seperate battery and it heated up OK. The three relays were under the central cover under the bonnet. 1x 50A and 2 x 20A, The 20a blown fuse was in that section too. There may be some corrosion problem in the relay holder terminals but at first glance they seem ok. A quick clean and vaseline should help. No circuit breakers have been tripped so I will now check the main dashboard fuses As the 12v pilot light on the control panel switch does not function when the engine is running I shall now try to find the control panel relay article and investigate that. Jeff Link to comment Share on other sites More sharing options...
Jiving Jeff Posted April 30, 2020 Author Share Posted April 30, 2020 UPDATE When the engine is running there is no 12v supply reaching the fridge via the cable from the relay. As yet I have been unable to tell which of the 3 under bonnet relays controls the fridge. Without knowing the corect relay it will be difficult to conduct a continuity check to locate the relay on the as a no reading could mean wrong wire from relay or a broken wire. GRRRR. On a seperate note, Is there a way to quickly locate my thread without scrolling through the threads ? Link to comment Share on other sites More sharing options...
BruceM Posted April 30, 2020 Share Posted April 30, 2020 Jiving Jeff - 2020-04-30 11:35 AM On a seperate note, Is there a way to quickly locate my thread without scrolling through the threads ? Book mark it in your internet browser. Link to comment Share on other sites More sharing options...
Keithl Posted April 30, 2020 Share Posted April 30, 2020 Jiving Jeff - 2020-04-30 11:35 AM UPDATE When the engine is running there is no 12v supply reaching the fridge via the cable from the relay. As yet I have been unable to tell which of the 3 under bonnet relays controls the fridge. Without knowing the corect relay it will be difficult to conduct a continuity check to locate the relay on the as a no reading could mean wrong wire from relay or a broken wire. GRRRR. What do the other two relays control? One will be aux battery charging and the other may be electric step operation? Unplug all three and see what stops working. Jiving Jeff - 2020-04-30 11:35 AM On a separate note, Is there a way to quickly locate my thread without scrolling through the threads ? Use the 'Search our forums' button in the blue title bar. Use a keyword, such as 'Dometic' or 'fridge' in this case, and your username and set the time limit to when you think you last posted. Keith. Link to comment Share on other sites More sharing options...
Keithl Posted April 30, 2020 Share Posted April 30, 2020 Are your Bessacarr MH's electrics made by Sargent? If so then download the 2004 MH wiring schematic on this page... https://sargentltd.co.uk/tech-support/article/Swift-Group-Schematics/25 It only shows 2 relays but does show that the fridge wiring is Red/Yellow so this may give you a clue. Keith. Link to comment Share on other sites More sharing options...
Alanb Posted May 1, 2020 Share Posted May 1, 2020 Jiving Jeff - 2020-04-30 11:35 AM UPDATE When the engine is running there is no 12v supply reaching the fridge via the cable from the relay. As yet I have been unable to tell which of the 3 under bonnet relays controls the fridge. Without knowing the corect relay it will be difficult to conduct a continuity check to locate the relay on the as a no reading could mean wrong wire from relay or a broken wire. GRRRR. On a seperate note, Is there a way to quickly locate my thread without scrolling through the threads ? Jeff, Is your vehicle fitted with a fridge/freezer, as that could explain the three relays, all operated from D+. I am looking at a wiring diagram for a 2004 Kontiki/Bessacar with fridge freezer, linked to by I think Robin? There are three relays in the top LH corner, split charge, fridge, and...... The third relay, labelled "Fridge Power Relay" is shown as connecting to the fridge via a separate fuse and a brown wire, while what I would have thought was the fridge relay, (at top LH corner of diagram) is shown as connecting via fuse 2 of a 4 way block and uses a red/yellow wire to connect to the fridge. The step relay is operated from this red/yellow wire. The step auto retraction power, and the step warning sounder are also connected via this wire. I cannot remember whether your step was auto retracting OK, but if it is, there is still the possibility of a faulty connection in the step relay area. I am unable to see why the spare F1 position on the 4 way fuseblock was not used, and a separate fuse is shown. Perhaps ease of drafting the diagram may be a factor? Alan Link to comment Share on other sites More sharing options...
Robinhood Posted May 1, 2020 Share Posted May 1, 2020 Alan, the RM7271 as detailed is not a fridge/freezer, just a fridge - which still begs the question what the third relay is. The 2004 diagram is, I think, good enough to provide diagnosis, but other, possibly more relevantdiagrams are contained in the "Technical Manuals" downloadable here: https://bessacarr-owners-club.org/info-centre/user-manuals.aspx The OP's 'van might conform to the version shown 2002, or 2003, (or even later, as the 7271 isn't detailed in the owners manual until 2004!) where there are detail differences, but not, IMO, anything over-relevant (the fundamental relay/fusing provision remains the same). I must admit I'm having trouble getting my mind round the doubling of relays and supplies for a fridge/freezer as opposed to simply a fridge, but the fact that the additional fuse is not shown in the spare fuse-way implies to me that it (and possibly the additional relay) is located somewhere else. Whatever, in theory if not in practice, the OP's fridge shouldn't need the additional provision. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.