Thetford N3142 FF on 12volt. (1 Viewer)

[DerryW]

Good afternoon
I have asked the questions below on the back of another posting, but realised it probably should have had its own thread.

The issue I have is; when plugged into EHU everything is fine, the panel shows the EHU symbol lit green and the fridge starts cooling, as soon as I disconnect the EHU cable the panel switches to gas and providing the gas is turned on the fridge starts to cool. However if I turn the gas off and start the engine, instead of the panel switching to 12v and the battery symbol lighting, the panel continually switches between the 12v battery symbol and the gas symbol and I can here a distinct clicking sound which I think is coming from behind the panel.
If I manually change the panel to 12v battery symbol, the symbol continuously flashes and the clicking sounds is still coming from behind the panel.
I have checked the 20a fuse on the Nordelettronica fuse board with a multi meter and the 20a which comes direct of the starter battery both are fine.
I fitted a brand new leisure battery only last week and having just checked that with multi meter it’s reading 13.44v so that’s okay.

Having read similar issues in the Search section, I have just checked the cables in the electrical block at the back of the FF by removing the external bottom grille as follows: -
Engine off. The thin orange wire = 0 volts, thin purple wire = 13.3 volts
Thick white wire = 0 volts
Thick red wire = 13.4 volts.
With Engine running: -
Thin orange wire = 14.4 volts
Thin purple wire = 14.5 volts
Thick white wire = 0.4 volts
Thick red wire = 14.5

Has anyone got any ideas why the FF won’t run on 12volts with the engine running. Please.

Thanks Derry

Quote Reply
Report

 

[IRHP]

Have you seen post 16 on this thread? I've since got a new upgraded pcb from Thetford despite being out of the 3 year warranty

Dometic 3 way fridge issue

Fridge works fine on gas and 240v. When I turn switch to batt position Red light comes on. Checked fridge fuse on E box all ok is there another low voltage fuse anywhere, looked behind grill outside can't see one, any ideas Cheers

www.motorhomefun.co.uk

 

[DerryW]

Thanks IRHP

I will check tomorrow (if it stops raining). Was your fridge doing the same, I.e. continually switching between 12v and gas symbol

 

[IRHP]

Thanks IRHP

I will check tomorrow (if it stops raining). Was your fridge doing the same, I.e. continually switching between 12v and gas symbol

No it wouldn't run on 12v and showed an error 6 if I tried to manually put it on 12v with engine running. If it was on auto it would run on gas

 

[GeoffnDee]

As the red and white thick wires are for the 12v heater element , it could be a faulty element. If you push the < > and the square button between them simultaneously the fridge should go to service mode and give any error code using the temp. range indicator on the right. (the amount of segments shown indicating an error code , one segment in the middle = error 4 , faulty element or power board ).
The N3142 12v heating element resistance should be between 0.61 and 0.78 ohms. if it is ok.

^{_{Subscribers  do not see these advertisements}}

 

[DerryW]

As the red and white thick wires are for the 12v heater element , it could be a faulty element. If you push the < > and the square button between them simultaneously the fridge should go to service mode and give any error code using the temp. range indicator on the right. (the amount of segments shown indicating an error code)

Thanks GeoffnDee
As I’m sure you can imagine, I spent hour upon hour yesterday reading all relevant previous posting from the search section of the forum, and found the one referring to error codes. It’s tipping it down at moment, when it eases I’m stright back out there and will give it a go.
Thanks

 

[DerryW]

Thanks GeoffnDee
As I’m sure you can imagine, I spent hour upon hour yesterday reading all relevant previous posting from the search section of the forum, and found the one referring to error codes. It’s tipping it down at moment, when it eases I’m stright back out there and will give it a go.
Thanks

Just checked. With FF turned on and in manual mode set to 12v battery symbol and with the engine off, I get error code 7 (replace power board assembly).
just as IRHP above suggested.
I will remove the PCB later today and report back.
Thanks to all above.

 

[DerryW]

I had a similar issue when we first got this van, only that time it would not even switch to battery, whereas this time it does if only for a short while before switching to gas.

That’s what made me think it couldn’t be the PCB.

I’ll know soon once it stops raining and I can get out there.

 

[GeoffnDee]

I may be wrong , but ,Would you not get a error code 7 (lack of D+ signal) anyway if the engine is not running and 12v selected?

 

[IRHP]

I had a similar issue when we first got this van, only that time it would not even switch to battery, whereas this time it does if only for a short while before switching to gas.

That’s what made me think it couldn’t be the PCB.

I’ll know soon once it stops raining and I can get out there.

I think you are right, if the 20 amp fuse on the pcb has gone it wouldn't work at all on 12v.

^{_{Subscribers  do not see these advertisements}}

 

[DerryW]

When you say “it wouldn’t work at all” do you mean the battery symbol on the panel wouldn’t light ? Mine does for a few seconds than moved to the gas symbol.

 

[GeoffnDee]

Do you get an error code if you check it with the engine running ?

 

[DerryW]

Just checked again. Error Code with engine running = 6.
Error Code engine switched off = 7

In both instances the 12v battery symbol was selected manually, not on A.

Thanks

 

[GeoffnDee]

It could be worth checking the red and white cable high current and heater element connections at the Power control module

 

[DerryW]

Hope you don’t mind me asking.
What voltage should I get from both red and white and do I check once with engine off then with engine running.

Also

^{_{Subscribers  do not see these advertisements}}

 

[DerryW]

Where are the heaters elements

 

[DerryW]

And power control module

 

[GeoffnDee]

I think that the readings you are getting at the rear of the fridge may be ok but I wonder if the connections further on at the power control module could be poor , causing a power drop , the heater elements and power control are on the rear of the fridge (The power control is near the bottom and may be behind a cover).
www.leisurespares.co.uk have , in their fridge spares section , parts diagrams for your fridge which you can download and the position of the parts on the rear of the fridge can be seen which may be useful .

 

[DerryW]

I’ve checked the D+ thin orange wire at the module with engine running and fridge switched on = 13.44volts

Checked the thick red wire at the module = 13.55volts

Checked the thick white wire at module = 00.5 volts.
Should I be getting higher voltage from the thick white wire ?

On my original message I said I could hear a clicking from behind the control panel at top of fridge, in fact the clicking sound is coming from the module.

 

[IRHP]

I’ve checked the D+ thin orange wire at the module with engine running and fridge switched on = 13.44volts

Checked the thick red wire at the module = 13.55volts

Checked the thick white wire at module = 00.5 volts.
Should I be getting higher voltage from the thick white wire ?

On my original message I said I could hear a clicking from behind the control panel at top of fridge, in fact the clicking sound is coming from the module.

No it's -ve which should be 0v with reference to 12v positive. I'd check the 20 amp fuse on the board .

^{_{Subscribers  do not see these advertisements}}

 

[GeoffnDee]

If you had the module cover off did you see a 20amp fuse and did it and its holder look ok ( No burned terminals or similar)
If you do find damage and need to replace the module make sure you get the modified part No 692247 (the old part was No 691101)

 

[DerryW]

I’ll check the 20a fuse in the PCB tomorrow.

Thanks for all your assistance.

 

[DerryW]

Well as GeoffnDee suggested, I checked the 20a fuse on the PCB and couldn’t believe what I found (see attached photos). Having spent ages reading so many similar case on this forum, surely this has to be a manufacturing defect. Makes you wonder how this fault hasn’t caused a fire,

You can see how the fuse as completely melted and fused itself to the actual cover of the module. It broke into 3 pieces when I removed it with pliers.

I now need to find a contact number for Thetford and see what they have to say.

Thanks to all those above especially Geoff Dee who responded.

 

[GeoffnDee]

Good to know you have found the cause of the problem ,It appears Thetford are aware about this fault and the modified power board with the later part number I have suggested is , I believe , because of this problem .
Perhaps IRHP, who also suggested checking the 20amp fuse , can help with a contact number as they had a very similar problem.

 

[DerryW]

IRHP

Would you happen to have a contact number for Thetford. Thanks

^{_{Subscribers  do not see these advertisements}}

 

[DerryW]

IRHP

Would you happen to have a contact number for Thetford. Thanks

IRHP

Would you happen to have a contact number for Thetford. Thanks

 

[IRHP]

IRHP

Would you happen to have a contact number for Thetford. Thanks

Not a number but I contacted them via email and got a quick response. They sent me a warranty claim form even though I was outwith the 3 year warranty. Infogb@thetford.eu