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post #11 of 24 (permalink) Old 26-03-2015, 18:49
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Thanks philoaks,
I went out to the van, disconnected it from EHU started the engine and turned the fridge on to auto, it immediately switched to 12v working. I then checked the voltage at the "12 DC heating element" terminal block and it read approx 0.6 volts! I would have thought that with the engine running it should read about 13-14volts...... any ideas??
Mel.

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post #12 of 24 (permalink) Old 26-03-2015, 19:05
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Originally Posted by Baron1 View Post
I know that the fridge automatically switches to 12v operation when the engine is running, my question is should there be a permanent 12v feed to the fridge heating element when on hook up?

I believe that there will be no 12v to the 12v element whilst on EHU.
I have recently renewed the 12v switching relay on my RMD8051 and am familiar with the circuitry. MH manufacturers do not all connect the fridge in the same way.
My Adria has a permanent 12v feed to the electronics but the 12v for the heating element is fed from the electtrobloc when the engine is running. This is then switched to the element by the 12v relay when the fridge is set to AES or manually to 12v.

Last edited by rayc; 29-03-2015 at 10:45.
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post #13 of 24 (permalink) Old 26-03-2015, 19:09
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Originally Posted by Baron1 View Post
Thanks philoaks,
I went out to the van, disconnected it from EHU started the engine and turned the fridge on to auto, it immediately switched to 12v working. I then checked the voltage at the "12 DC heating element" terminal block and it read approx 0.6 volts! I would have thought that with the engine running it should read about 13-14volts...... any ideas??
Mel.
On my Adria it would suggest there is a problem in the supply from the electrobloc. The electrobloc has a fridge 12v output which supplies an output when it detects the engine is running [alternator providing current]. This is fed to the fridge via a 20a fuse located close to the electrobloc.

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post #14 of 24 (permalink) Old 26-03-2015, 19:24
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Thanks Ray,
When you say close to the electrobloc do you mean a separate fuse block? i.e. not actually on the electrobloc itself?
Mel.

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post #15 of 24 (permalink) Old 26-03-2015, 19:28
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To clarify: The electrobloc receives the voltage from the engine battery via a 20A fuse adjacent to it. The electrobloc switches the voltage to the fridge when it detects the engine is running i.e. alternator has output. The fridge relay then switches the positive to the element when the fridge is on 12v or AES.
I have tried attaching the relevant part of the schematic but doubt it is clear enough.

Last edited by rayc; 29-03-2015 at 10:45.
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post #16 of 24 (permalink) Old 26-03-2015, 19:30
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Originally Posted by Baron1 View Post
Thanks Ray,
When you say close to the electrobloc do you mean a separate fuse block? i.e. not actually on the electrobloc itself?
Mel.
A separate fuse. On this block close to the electrobloc.

Last edited by rayc; 29-03-2015 at 10:45.
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post #17 of 24 (permalink) Old 26-03-2015, 19:30
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[QUOTE=rayc;1341689]I believe that there will be no 12v to the 12v element whilst on EHU.
I agree Ray, I was suprised when I found 13 volts at the heating element with the engine off, maybe it was caused by a sticky relay???

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post #18 of 24 (permalink) Old 26-03-2015, 19:33
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Originally Posted by rayc View Post
A separate fuse. On this block close to the electrobloc.
Right, I will have a look for something like that tomorrow.
Many Thanks
Mel.

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post #19 of 24 (permalink) Old 26-03-2015, 19:35
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Quote:
Originally Posted by Baron1 View Post
Thanks philoaks,
I went out to the van, disconnected it from EHU started the engine and turned the fridge on to auto, it immediately switched to 12v working. I then checked the voltage at the "12 DC heating element" terminal block and it read approx 0.6 volts! I would have thought that with the engine running it should read about 13-14volts...... any ideas??
Mel.
Hi Mel.

Curiouser and curiouser!

As you say, with the engine running and the fridge auto switched to 12v you would expect to see at least 12v across those terminals. A couple of things spring to mind.

I assume you've tested the meter direct across the battery, or similar, to ensure it's working ok.

Do you know if the AES fridge is actually cooling when on 12v with the engine running? It sounds as though the fridge is seeing the sense circuit from the alternator and is able to auto select 12v operation but if the 12v to run the element isn't there the fridge may not realise and therefore not show a fault condition.

I suspect it probably isn't cooling on 12v and this is where your strange readings come into it. I'm not sure where the 12v for the heating element is derived. Prior to AES fridges it would have been probably from the engine battery via a relay which would be operated by the sense output from the alternator.

As the AES fridge itself does the "sense" work nowadays then this supply could in theory be derived straight from the engine battery or even the leisure battery. Whichever it is there should be a fuse in the circuit somewhere. To be reading 0.6v suggests that there is still something connected to that wire so you may be looking at a corroded connection or a fuse block that has melted and is barely making a circuit.

If you've got a wiring diagram in the van manual then hopefully it will point you towards where that 12v element supply comes from. That would be my first port of call.

Good luck!

Phil
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post #20 of 24 (permalink) Old 27-03-2015, 16:01
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As you say Phil, curiouser and curiouser and now even curiouser!!!
Yesterday when I left the van I was getting 0.75 volts across the 12v heating element connector block, I went out this morning to have a look for the fuse that Ray alluded to and thought I'd just check the voltage again before I started.......13.6 volts!
What I still don't understand is, if there is >12v present at the element connector why is the element not heating and the fridge not cooling ..or is there another relay between the connector block and the element that operates when it receives the signal from the alternator?
As for the 0.6 volts that I have been measuring at the connector I have two theories, either the relay that operates when the engine is running was not fully disengaged and letting a small voltage through or the voltage was a back EMF from the permanent 12v supply to the fridge that supplies the light etc.????
Anyway we are off for a few days away and then to the Peterborough Show so that will be a good test for the electrics.
Thanks all for help and advice, I will report back with any news.
Mel.

Time flies like an arrow, fruit flies like a banana.

"Wings, the band the Beatles could have been" - Alan Partridge.

There are eleven types of people in the world, those that understand Roman numerals........and those that donīt.
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