Fridge problem

[Speedyian]

My problem is that I seem to have lost the 12v feed to my fridge. I have an Autotrail Imala with a Dometic RMS 8501 fridge. Yesterday the fridge stopped working all lights went off no audible warning, as if it had just been switched off.
I have a 12v neon tester and found no supply to the fridge. I checked the fuse in the Sargent EC155 unit by substitution and found that it was ok.
Further testing showed that there is no output at the fuse on the Sargent unit although all other outputs are ok.
I then disconnected the hook up and ran the engine and tried to run the fridge but still nothing.
I have no access to circuit or wiring diagrams as we are away until Friday.
Does the fridge have a separate supply into the Sargent unit, and if so is it likely that a fuse further back in the supply has blown?
All other functions from the Sargent unit are working and leisure battery is showing as fully charged.
Thanks in advance.

 

[Ivory55]

I think that it only runs on 12v when the engine is running, so is there a fuse on the van side blown

 

[Ivory55]

Ps our autotrail only running with the engine

 

[Larby]

Interface box may be found behind drivers seat. Look in there for another fridge fuse

 

[Richard n Ann]

Is the supply for the 12v element different? Must be... Looks like the control voltage has failed?

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[Speedyian]

The control for the fridge is through the the 12v supply. Therefore no 12v supply and the fridge will not not run either on mains or gas.

 

[Speedyian]

Larby I have had a look in the box behind the drivers seat and both fuses marked fridge look fine, however the one marked fridge has no output, whereas the one marked fridge D+ does have a 12v output.

 

[Ivory55]

Larby I have had a look in the box behind the drivers seat and both fuses marked fridge look fine, however the one marked fridge has no output, whereas the one marked fridge D+ does have a 12v output.

Once I get to that stage I have to call someone in, that is the limit of my technical ability, haha

 

[Richard n Ann]

Could you pick a multimeter up from screwfix and trace the dead output back further?

 

[GeoffnDee]

The EM 40 interface has fuses for the fridge in it including the constant supply , there may be also a fuse at the battery connection supply to it.

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[Speedyian]

Where is the EM 40 interface

 

[Larby]

Larby I have had a look in the box behind the drivers seat and both fuses marked fridge look fine, however the one marked fridge has no output, whereas the one marked fridge D+ does have a 12v output.

Fuses can "look fine". Test them with a meter or swap and see if both items still work.
You had engine running ? with 12v on d+ but no 12v? Fuse further up the circuitry?

 

[Speedyian]

Don't have access to a meter until I get home on Friday. Fridge D+ output without engine running.

 

[GeoffnDee]

Where is the EM 40 interface

Normally behind the Drivers seat on an Autotrail , ( May not be fitted on an Imala), if not ,your hand book may give its location if fitted (It could also be a EM50or60 but should contain the fuses for the fridge if fitted). If there is one fitted it should have its own supply fuse either at the battery or on the fuse board .

 

[autorouter]

Not sure where it is (near the leisure battery perhaps) but it looks like this:

EM40 Interface Box | Shop | Sargent Electrical

It has two fridge fuses, one for the element supply and one for D+, which is the engine running signal that tells the fridge to switch to 12V.

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[Richard n Ann]

Not sure where it is (near the leisure battery perhaps) but it looks like this:

EM40 Interface Box | Shop | Sargent Electrical

It has two fridge fuses, one for the element supply and one for D+, which is the engine running signal that tells the fridge to switch to 12V.

What's the internal light fed off?

 

[mitzimad]

Check any fuses around the vehicle battery

 

[GeoffnDee]

What's the internal light fed off?

The PSU is also connected to the fridge .

 

[Speedyian]

Never rains but it pours. Broke my reading glasses so I can't mess about in fuse boards. It will have to wait until I get home.

 

[Speedyian]

I am sorry for the delay in this update, but here is the conclusion with the cause and remedy. As stated previously the fault had to wait until we got home. After much research to obtain circuit diagrams, I retested from the start. to cut a long story short all inputs to the fridge from the sargent unit and the EM 40 interface (fuses behind drivers seat) were correct with engine stopped and engine running.
This only left the fault to be at the Polyswitch unit (back of fridge) or the control panel PCB. Luckily there is a 12v output terminal at the Polyswitch unit that is not used and I was able to test for an output which was present. This only left the control panel PCB to suspect. As the control panel PCB is approx £180 to renew. I sent a comprehensive report of my finding to the Dometic technical help and after four days they got back to me to confirm my suspicions. I then had to source a new control panel PCB and these are not available in great numbers, however, I got one from Swordcrown Caravans who were very helpful by checking against the fridge product No that the one they had got was the correct one. Part arrived the next day, I fitted it this morning and tested and the fridge worked on gas, 240v and 12v.

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