Fridge wiring question

[tviall]

A question please about wiring for a Dometic RMD8551 AES Fridge. Is the fridge simply wired into a 12v supply and the fridge decides via its D+ signal whether to turn on or not, or is the 12v switched via a relay somewhere?

Thanks

[Kabundi]

http://etime.com.au/media/blfa_files/8501_8505_8551_8555_2.pdf

 

The above document should answer your query

[tviall]

Thanks. I have the installation instructions but they seem to contradict themselves.

[arthur49]

I would have thought it depends how the converter has wired it? What make/model/year is your van?

[Robinhood]

For an AES fridge. it isn't unknown to wire the 12V absorption heater through an additional (D+ operated) relay, but AFAIK it is (much) more conventional to directly wire that 12V supply, and rely on the AES circuitry to do the switching via its own logic.

 

As an example, on (most) Schaudt Electroblocks the D+ fridge relay is contained within the EBL. Different connection points are provided for standard 3-way fridges and AES/Compressor fridges, the latter bypassing that EBL-provided D+ relay.

 

Connecting in this way will ensure switching to 12V when the AES fridge is set to "Auto" and the engine is running. There is a corollary to this, however, which you may see as an advantage or disadvantage, depending on your point of view. If the AES fridge is switched manually to the 12V setting, it will run on 12V regardless of whether the engine is running or not (and, of course, under these circumstances the battery(ies) will take a substantial hit if the engine isn't running).

[Alanb]

Perhaps the OP is becoming confused by the fact that these fridges require two 12V supplies. One which must be maintained while the fridge is in use, connected to terminals C & D. A second, higher current heating element supply, should be connected to terminals A & B. (See page 18, of the instructions linked to above.) It is this heating element supply which is controlled externally by a relay for manualy selected fridges, and internally by AES fridges which also require the D+ connection.

 

Alan