Taking your newer Dometic refrigerator boondocking?
Want to drop 1/2 an amp of constant 12V power?
Don't care about some potential condensation?
Here is how you fix this problem
First there are 2
different heaters in your Dometic DMR702:
1. The LAC "Low Ambient Control" heater - this one only runs when the outside air temperature is cold enough. It is possible that the fridge compartment can run too cold and the freezer to hot under some conditions. So they fix it by introducing a bit of a heat source into the fridge section. This heat source is a 18 ohm resistor burning off almost an AMP of 12V power.
2. The real crime though is the condensation control heat loop that runs ALL the time and burns off 1/2 AMP of 12V power. Just to prevent condensation from occurring between the two doors.
Some folks remove a fuse to disable these but you can do MUCH better, like disable the heater but still have lights in your fridge.
Here is the LED light and heater connection PC board as it comes out of the top of the fridge section:
And this is the top side of the PC board after removing from the plastic housing:
Note the 2 pin/wire connection - this is the heat loop connection and the simplest thing you can do is leave this disconnected. This will disable the heat loop but leave the LAC function enabled. Since the LAC is thermostatically controlled it will not be a factor in many cases. BTW that large beige ceramic block is the LAC heater.
Now if you want to get fancy you will need to add a couple of switches here. I used some PC board mount slide switches, one for the LAC and another for the heat loop. This picture shows the top side of the PC board modified for both of these switches. The LAC switch (in the middle of the picture) is inline with the PC board traces for the LAC and one has been cut between the switch mounting pins. The heater loop switch is on the right side and all you see is a couple wires connected to the switch pins. This switch was mounted in an otherwise open area of the PC board with no traces. Note that the switch is a DPST and both poles have been connected to the wires.
This picture shows the same switch modifications but from the bottom side of the PC board. Not much to see on the LAC switch since it is using the traces on the other side of the board. But here you can see where the wires hook up for the heater loop: one to the terminal block post and the other to the 12V input on the 4 wire terminal block. The PC board trace that normally connects these two terminal block pins has been cut.
And this last picture shows the PC board mounted back into the modified plastic housing. The housing has been cut around the switches to allow them to sit flush with the bottom of the housing. When mounted back in the fridge you will not even see the switches unless you look. I recommend labelling which switch is which and which direction OFF/ON are in.
Turn off that head loop switch and you can save 12 AH per day while boondocking. Keep those batteries charged and the beer cold my friends