Any idea why rmd8505 Dometic fridge beeps very rapidly when put on 12v?

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hornsofallign

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Hi folks,

Our RMD8505 works perfectly on gas, 230v, and before this week,12v. Now, when I turn the fridge to 12v, a rapid beeping starts immediately, along with a perfectly synchronised ‘dull clicking’, but there are no warning lights.

The ‘van has been sat unused for 3 months, but heated to 10c, with the fridge off.

I haven’t found anything relevant in the manual, or online, so I’m hoping to call on your knowledge and experience.

Thanks in advance
 
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Is the engine running when you switch the fridge to 12v as it wont work on most vans without engine running.
 
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The 'beeping' I reckon is the fridge emitting a warning that it is trying to work but there is no source of power.
The clicking is the gas system trying to start and there is no gas supply.
 
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As KUSKUS & Emmit have said it won’t work on 12v static only when van moving or engine running, we find gas best option even on hook up which is not often😊
 
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Is your fridge the type that has auto energy selection (AES) and also manual selection? Did it work previously with 12V selected manually? Many motorhomes don't work on 12V without the engine running. However if it has an Elektroblock (EBL) then that option may be available. Is there an EBL, and if so which model number is it?

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It could just be the 12v supply fuse. It has 2
 
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No 12v as engine not running so is trying to default to the next option of gas.

You say no warning lights. Is that no lights at all of any sort or just no warning lights?
 
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Our lower rear pcb board had a lot of oxidation on the connector edge strips which stopped it working after being stood not used by last owner
 
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Thanks all for the many responses. I’ll try to respond to the follow-up questions….

The problem occurs even with the engine running, but I was pretty sure the fridge used to work in 12v even without the engine running. Though, all your comments are making me wonder now 😳
Changing from the AES to a manual setting doesn’t help. It occurs either way.
When on gas or 230v the green ‘working’ light functions correctly, so it’s just that the warning beep is not accompanied by any warning lights.

We have an EBL266 and a Victron invertor, but I’m not sure what, if any, changes the fitter (vanbitz) had to do to make them work together. They’ve been fine for 2 years.

When back at base I’ll check the fuses, if I can work out how to access them.

Did you need to replace the oxidised PcB?

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The EBL266 seems to be a very early model of the EBL, with less facilities than an average one. The fridge supply from the starter battery uses the same fuse as the split charge relay, 30A, but uses a separate wire from the fuse to the EBL. If that 30A fuse blows, it would stop both the fridge and the split charge relay, which charges the leisure battery while the engine is running.

Do you know if the leisure battery is charging OK when the engine is running? You can check if the leisure battery voltage is over about 13.3V when the engine is running, which means it is being charged. So if that happens, the 30A fuse must be OK.

There is also a 16A fuse on the panel, possibly labelled 'Kuhlschrank' (= fridge) that is worth checking. Maybe check with a meter to see if power is reaching the fuse. The power should only be on when the engine is running.

Maybe you could post a pic of the EBL and the panel.
 
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autorouter said:
The EBL266 seems to be a very early model of the EBL, with less facilities than an average one. The fridge supply from the starter battery uses the same fuse as the split charge relay, 30A, but uses a separate wire from the fuse to the EBL. If that 30A fuse blows, it would stop both the fridge and the split charge relay, which charges the leisure battery while the engine is running.

Do you know if the leisure battery is charging OK when the engine is running? You can check if the leisure battery voltage is over about 13.3V when the engine is running, which means it is being charged. So if that happens, the 30A fuse must be OK.

There is also a 16A fuse on the panel, possibly labelled 'Kuhlschrank' (= fridge) that is worth checking. Maybe check with a meter to see if power is reaching the fuse. The power should only be on when the engine is running.

Maybe you could post a pic of the EBL and the panel.
Click to expand...
So sorry. It’s a 226C +OVP. We’ve also had a Sterling power B2B, so I assume that’s replaced the split charge relay.



image.jpg
 
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hornsofallign said:
Thanks all for the many responses. I’ll try to respond to the follow-up questions….

The problem occurs even with the engine running, but I was pretty sure the fridge used to work in 12v even without the engine running. Though, all your comments are making me wonder now 😳
Changing from the AES to a manual setting doesn’t help. It occurs either way.
When on gas or 230v the green ‘working’ light functions correctly, so it’s just that the warning beep is not accompanied by any warning lights.

We have an EBL266 and a Victron invertor, but I’m not sure what, if any, changes the fitter (vanbitz) had to do to make them work together. They’ve been fine for 2 years.

When back at base I’ll check the fuses, if I can work out how to access them.

Did you need to replace the oxidised PcB?
Click to expand...
No, I cleaned up all the terminals and all the connectors making sure they are springy enough to make contact.
If you are able and ok With testing here is the wiring for 12v

1711897915782.png
 
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If the TV and fridge share the same supply, and the cable is too small, the voltage drop could be enough to set off the fridge low voltage alarm.
 
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The EBL226C with OVP manual is here:

When the engine is running, the fridge 12V heater element is supplied by a 20A fuse near the starter battery, through a wire to Block3 Pin3 on the front of the EBL. That's the positive, the negative goes to Block3 Pin2. So if you had a meter you could check that you get 12V at that point. The 20A fuse is usually one of three, the others are the 50A fuse for the split charge relay, and a small fuse, maybe 2A to 5A, for the D+ (Engine Running) signal. Since you have a B2B and not a split charge relay, possibly the 50A fuse has been removed.

The other thing to check is the AES fuse, 15A, 4th from the left on the front of the EBL. If you switch the fridge to 12V manually when the engine isn't running, you should get power going to the fridge heater element from the leisure battery through that fuse. Many motorhomes are wired so this isn't possible, but with this EBL the option is available.

If neither of these two supplies gets the fridge working, then I think you need to look at the supply at the back of the fridge, as in the pictures in 1967bowesj's link. If the power is getting to the terminals A and B, but the fridge isn't working, then maybe the heater element has failed, or the fridge control board is faulty.

The element can be checked by measuring its resistance with a multimeter. Are you OK with using a multimeter?

Usually these terminals can be accessed by removing the lower external fridge vent, usually no need to take out the fridge to check the elements.

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