Setting for Fridge

[Alan P.]

My 76 Surf Side was largely rewired by a marine electrician who installed deep cycle battery and sophisticated multi-stage charger. The fridge (original0 has the ability to run on 12V or 115V or Propane. The electrician told me there was no need to switch back and forth from 12V to 115V when switching from the deep cycle or when attached to the tow vehicle when I then plug into shore power. So I stopped doing this unnecessary step and leave it on 12V at all times except the rare occasion when I use propane.

Question is: Why is the performance (cooling) so pathetic when being towed or sitting at a camp site running on the deep cycle, compared to the very efficient cooling when attached to shore power. I would have thought that if on 12V setting the shore power is being reduced to 12V. I thought that 12V is 12V and it should make no difference if it is backed up by shore power or not?

Can anyone explain this in baby talk for the electrically challenged. Would like to understand.

[Chester Taje]

Is this the original fridge?My fridge is a straight 12volts.It is a high efficient model.It works well for me.If yours is original then i would run on 110 volt or propane when camped.12 volt when travelling.

[Alistair Camelford]

Alan, the old Dometic type frig works by heating the ammonia coolant and letting it "flow" to an expansion chamber to cool by absorption. There are three distinct heating elements "wrapped" around this tube...the 110 heats the ammonia most efficiently in the electric mode, the 12 volt just barely maintains the cooling process but there is not enough power in the 12 volt circuit to initiate cooling from a warm frig...leave that to the more powerful 110 circuit. On the propane side, you'll find that the heater fired by propane to be very effective if it is working properly.
I have added a small 2" fan in the top part of the coils to help bring more outside air in to the fins and aid in the cooling process(a 12volt computer fan or a "Koolatron" replacement fan does the job.
Also think about disconnecting the charge cord from the tug when you have a long stop of an hor or more...the frig on 12 volt is a real battery killer!
Cheers...Alistair

[Per Walthinsen]

The Dometic in mine has a 123 watt 12 volt element and a 175 watt 120 volt element. Therefore the 12v is pathetic and the 120v does just fine. I run it through an inverter when on the road. 6 gauge charge line from car bettery to the converter, makes quite a difference.

[Byron Kinnaman]

My 76 Surf Side was largely rewired by a marine electrician who installed deep cycle battery and sophisticated multi-stage charger. The fridge (original0 has the ability to run on 12V or 115V or Propane. The electrician told me there was no need to switch back and forth from 12V to 115V when switching from the deep cycle or when attached to the tow vehicle when I then plug into shore power. So I stopped doing this unnecessary step and leave it on 12V at all times except the rare occasion when I use propane.

[b]Question is: Why is the performance (cooling) so pathetic when being towed or sitting at a camp site running on the deep cycle, compared to the very efficient cooling when attached to shore power. I would have thought that if on 12V setting the shore power is being reduced to 12V. I thought that 12V is 12V and it should make no difference if it is backed up by shore power or not?

Can anyone explain this in baby talk for the electrically challenged. Would like to understand.

I seem to recall that some had an automatic switch over. Electronics would detect when 120 was on and switch to 120 Volt operation from 12 Volt. I would suggest that you look at your manual or go to the manufacturer's web site and down load the manual. If you can't do the contact the manufacture.

[Gerry]

My dometic fridge has that knob on the back that has to be set to either...120V...12V or propane then also a knob with 1-10.... 10 being the coldest setting and the recomondations is to set at 4.
I've always set it on 4 and it has worked fine although better if on 120V then 12V.
I like the idea of getting fridge cold with 120V a day before heading out then let the 12V do it's thing while on the road just to maintian.
But I was wondering, if the fridge needs to be level to work properly, how does it work properly going down the road with dips, hills and bumps?
Gerry the canoebuilder