Dometic AES fridge RMT7558T 3 way energy source

[Absolutebeginner]

I feel like I have just discovered the secret of fire, but felt it worth putting on the forum as I have not seen it mentioned when there have been discussions of problems with an absorption fridge. In my case the answer turned out to be so simple, just when I thought that I was staring a big bill in the face.

 

I put the mains onto the motor home 2 days before going away to get the temperature down and it takes ages. The last time I put it on 3 days beforehand and it didn't work at all. On the way down on a 3 hour run it didn't seem to work on 12v either. When on the camp site I used gas and it was fine.

 

I found Mike Cook, a Dometic mobile technician based in Dorset who came to my home near Weston Super Mare where the motor home is parked and straight away suggested that the problem was that I park on my sloping drive!

 

I put the vehicle on chocks to get near level, and hey presto.....everything works.

 

The Dometic manual does not mention that the fridge is sensitive to the amount of 3 degrees out of plumb. John Wickershaw's book mentions it....but only in the section on installation.

 

Clearly 12v was working on the way to site, but couldn't do much to cool a full fridge load in 3 hrs. And some say that 12v cannot do much more than hold the existing temperature.

 

I think that this verticality requirement is so important that it should be more widely published, hence this posting.

 

But then I guess you old hands will say "I could have told you that", but it isn't written where I could find it manufacturers!

 

 

[Mel B]

Ain't knowledge a wonderful thing! The older type fridges used to be very tilt-intolerant, but nowadays they are much better.

 

In our current motorhome we have a standard 3 way fridge, but prior to that our Rimor Sailer van had a wonderful large AES one with separate fridge and freezer - pure luxury. This is the ONLY thing that I miss (although hubby does miss the really, really large rear garage when he's tootling round car boot sales for lots of goodies!!!).

 

Oh yes, back to the point, if your AES fridge is wired up anything like ours was in the Rimor you need to make sure you turn it off fully and don't leave it on 12v when on site or when you're not using the van, especially when you've turned the gas supply off - our Rimor fridge would work off 12v when the engine WASN'T running! 8-)

[Derek Uzzell]

Absolutebeginner

 

According to John Wickersham all higher-specification Electrolux/Dometic 3-way refrigerators made since the mid-1980s have been 'tilt tolerant'. The amount of tilt tolerated varies according to the model, but it can be up to 6 degrees. I can't tell you how much tilt a RMT-7558 should be able to handle, but plainly it's less than your drive's slope.

 

It's probable that people 'living' inside a motorhome will tolerate less tilt than a modern Dometic fridge and, consequently, will tend to level the vehicle for the sake of comfort, so may not experience the problem you've encountered. However, as you've discovered, difficulties can arise when the vehicle is parked-up well out of level.

 

12V-operation of recent Dometic appliances like yours is much more effective than that of earlier fridges. I have a RM-7605 fridge/freezer and, after 2 hours driving (with the fridge's temperature-regulating knob set to mid-position), the fridge's interior will have cooled down considerably from ambient temperature. After a 6-hour ferry-crossing (with the fridge off), followed by a 3-hour drive, the contents of the freezer compartment are solidly frozen.

 

In my fridge's Dometic manual, there is a single sentence in the trouble-shooting section warning that, before calling Dometic's Service Department, one of the things to check is that "The refrigerator is not tilted excessively." However, no clue is given as to what "excessively" means in this instance.

[Derek Uzzell]

Mel B - 2010-10-31 4:52 PM

 

...Oh yes, back to the point, if your AES fridge is wired up anything like ours was in the Rimor you need to make sure you turn it off fully and don't leave it on 12v when on site or when you're not using the van, especially when you've turned the gas supply off - our Rimor fridge would work off 12v when the engine WASN'T running! 8-)

 

Interesting that...

 

It's certainly the case that Dometic fridges like the 7-Series should always be switched completely off when the fridge is not in use. This stops the 12V current drain that powers the fridge's electronics (irrespective of whether the fridge is operating on gas, 230V or 12V) from gradually flattening the motorhome's leisure-battery. But I'm surprised your Rimor's wiring apparently omitted the usual ignition-operated relay to allow 12V-cooling only when the vehicle's engine was running.