Originally Posted by KyDan
When a fridge is on LP gas mode it still requires a small amount
of 12v power because the control board needs it to function.
It does NOT run (cool) all the time. Once the interior temp is cold enough
the LP will shut off.
If it's running (cooling) on AC 120v the board still needs 12v DC to operate.
Same as LP- it will shut off the AC heater once the inside temp is cold
enough to satisfy the "thermister" that sends signal to the control board
that it's cold enough.
Perhaps the high wall PUP models have a fridge big enough for the control boards and thermistors - the regular PUP and A-frame fridges DO run continuously. Therefore NO control board or thermistor is needed. The LP is regulated manually by a valve in the gas line. AC, when it has any regulation, has a manually operated SCR similar to incandescent light dimmers. All 3 phases (DC, AC, LP) in these small fridges run continuously, which makes for easy trouble-shooting. If the chimney is hot, heat is being supplied.
If you want to see for yourself, you are welcome to pay me a visit and check out my A122. I defy you to find a DC control board or a thermistor on the fridge.
Furnace and hot water heater (newer versions) do have some DC components. My old water heater had a pilot light for ignition. There is also a switch to turn these appliances off to prevent parasitic battery drains.
2000 Coleman Westlake PUP (12ft box, no slide-outs)
towed with 1992 Ford Explorer
2014 Rockwood A122 A-frame
towed with 2008 Hyundai with WDH