12volt fridge

[Mkrob65]

Can anyone help . I’ve got a 3 way fridge . When engine running the 12v switch is not lit up . I have power going to the fridge as when I turn it to gas the ignition switch flashes and fridge lights up .

 

[Richard n Ann]

I think the main element supply is different, 20a fuse somewhere and sometimes the fuse holder fails. No experience of it myself, just what I've read on here.

 

[Phil 748]

Hi had the same problem with our AS, it was a bad connection to relay that is connected to the ignition switch, so the relay did not switch the 12v from Main Batt when driving. took awhile to find the relay, you may need to find a wiring diagram for your MH to locate it

 

[Mkrob65]

It’s annoying as last year when I took it out it worked fine . I’ve had fridge out but can’t see a fuse anywhere

 

[Mkrob65]

Hi had the same problem with our AS, it was a bad connection to relay that is connected to the ignition switch, so the relay did not switch the 12v from Main Batt when driving. took awhile to find the relay, you may need to find a wiring diagram for your MH to locate it

It’s a 1995 boxer with a holdsworth conversion. Think I may have to live without the 12 volt

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[Phil 748]

Hi one thing you may want to check with ours when the relay was not working it also stop the Hab batt being charged when driving

 

[Mkrob65]

The jab battery is connected to solar panels. Would this make a difference

 

[Phil 748]

Hi shouldn't do, but on ours if the relay does not switch then no 12v to the fridge when driving.

 

[Mkrob65]

Hi shouldn't do, but on ours if the relay does not switch then no 12v to the fridge when driving.

Any idea where the relay may be

 

[Phil 748]

Hi on ours it is with Hab Batt

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[Itsmcb]

Hi the relay and little fuse box is probably under the bonnet near the starter battery. There may be two, the second is the split charger relay.

 

[Itsmcb]

This sort of thing

 

[jezport]

Have you checked for 12v at the fridge?

 

[Itsmcb]

The jab battery is connected to solar panels. Would this make a difference

No, the power for the 12v element is supplied by the alternator via the engine battery and a relay. The 12v supply for the fridge controls and ignition is separate and supplied from the habitation battery. Your solar will be charging the habitation battery.

 

[Itsmcb]

It's also possible that the little light in the switch has stopped working, mine has but the fridge still works

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[Mkrob65]

Have you checked for 12v at the fridge?

I used a circuit tester and was getting no power to switch

 

[Itsmcb]

Let us know how you get on

 

[Mkrob65]

Hi the relay and little fuse box is probably under the bonnet near the starter battery. There may be two, the second is the split charger relay.

Think I will change both relays . There’s some inline fuses near the battery but they are ok

 

[Mkrob65]

Let us know how you get on

I’m back at work tomorrow. Going order 2 new relays if that doesn’t fix it . I will try find a campervan specialist. Bit few and far between near Milton Keynes

 

[Phil 748]

Hi if you check first if you getting 12v to the relay on our relay it pin 85 from ignition switch do this with ignition on

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[autorouter]

A relay is an electrically operated switch. A small trigger current flowing through a magnetic coil (85 and 86) pulls the heavy-duty contacts (30 and 87) together. The trigger current comes from the D+ signal, which is ON when the engine is running, and OFF when the engine stops.

So first, with the engine stopped and the relays removed, test terminal 30 on the relay socket. It should be permanently connected to the starter battery positive, via a fuse. If it's not ON, check the fuse. This applies to both the relays. One will be a 'split charge relay' for charging the leisure battery, the other will be the fridge relay.

Next, still with the relays removed, test terminal 87 on the relay socket. For one of the relays (the split charge relay) terminal 87 will be at the leisure battery voltage. For the other (the fridge relay) there will be no voltage. So now you know which relay is which. If both have no voltage, check the leisure battery fuse.

Again with the relays removed, test terminals 85 and 86 on the relay socket. There should be no voltage. Now start the engine. Terminal 86 should go to ON on both relays. If not, there's a problem with the D+ signal

Stop the engine, and plug in the fridge relay. Test terminal 87, which should stay at no voltage. If it goes to ON the the relay has failed (stuck ON).

If all OK, start the engine and test teminal 87 again. it should now be ON, proving that the relay is functioning correctly. If not, the relay has failed (stuck open)

 

[Mkrob65]

A relay is an electrically operated switch. A small trigger current flowing through a magnetic coil (85 and 86) pulls the heavy-duty contacts (30 and 87) together. The trigger current comes from the D+ signal, which is ON when the engine is running, and OFF when the engine stops.

So first, with the engine stopped and the relays removed, test terminal 30 on the relay socket. It should be permanently connected to the starter battery positive, via a fuse. If it's not ON, check the fuse. This applies to both the relays. One will be a 'split charge relay' for charging the leisure battery, the other will be the fridge relay.

Next, still with the relays removed, test terminal 87 on the relay socket. For one of the relays (the split charge relay) terminal 87 will be at the leisure battery voltage. For the other (the fridge relay) there will be no voltage. So now you know which relay is which. If both have no voltage, check the leisure battery fuse.

Again with the relays removed, test terminals 85 and 86 on the relay socket. There should be no voltage. Now start the engine. Terminal 86 should go to ON on both relays. If not, there's a problem with the D+ signal

Stop the engine, and plug in the fridge relay. Test terminal 87, which should stay at no voltage. If it goes to ON the the relay has failed (stuck ON).

If all OK, start the engine and test teminal 87 again. it should now be ON, proving that the relay is functioning correctly. If not, the relay has failed (stuck open)

I have found a black oblong box with a lot of wires and found I spade connector disintegrated.

 

[autorouter]

I have found a black oblong box with a lot of wires and found I spade connector disintegrated.

I think you know this already, but a relay looks like the black plastic box in the picture from Itsmcb' s post #12, with the four (or sometimes five) wires on spade terminals at the bottom. Is it like one of these or different? Does it have any label or marking on it? Was it near the battery or maybe at the back of the fridge?

 

[Mkrob65]

I think you know this already, but a relay looks like the black plastic box in the picture from Itsmcb' s post #12, with the four (or sometimes five) wires on spade terminals at the bottom. Is it like one of these or different? Does it have any label or marking on it? Was it near the battery or maybe at the back of the fridge?

I can’t see a relay under the bonnet or near the fridge . As it’s a 95 boxer I’m wondering if oblong box is an old design relay . Going take it off and see if I can find any numbers

 

[Itsmcb]

I can’t see a relay under the bonnet or near the fridge . As it’s a 95 boxer I’m wondering if oblong box is an old design relay . Going take it off and see if I can find any numbers

My picture is from a 96 boxer

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[Jev88]

It’s a 1995 boxer with a holdsworth conversion. Think I may have to live without the 12 volt

I had a Ducato 1999 with Holdsworth links... Have you located the inline fuse - red or green wire - very close to engine battery.

 

[Mkrob65]

My picture is from a 96 boxer

Got nothing looking like that

 

[Jev88]

 

[Mkrob65]

View attachment 521213

I’ve got the green wire with glass fuse . That wire goes to black oblong box with load of other wires

 

[Mkrob65]

View attachment 521213