This all concerns the
Norcold model N300.3rh which I have in my 2619 from year 2006; I don't know if TrailManor still uses this refrigerator in current models. In
many Threads concerning this refrigerator, people (including me!) keep complaining about the way it tends to freeze lettuce in the coldest part of the night (just before dawn); and then warms up to 50F+ during the daytime (if you forgot to turn the danged thermostat dial back down).
This post includes a wiring diagram (please see the attachment, "norcold_n300.rh_3-way_wiring.jpg"). Then, in the following post, I discuss the electrical current path in each of the 3 operating modes (12VDC, 115VAC, and Propane).
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The diagram, copied from the Service Manual, labels the following parts with numbers, in circles next to the parts:
#1: 120VAC power cord ("hot", "neutral", and chassis ground).
#2: Wire Terminal Block. All connections are straight through. (1-8, 2-7, 3-6, and 4-5).
#3: AC power fuse. (3 amp fuse on the Norcold's 120VAC "hot" wire out from terminal block).
#12: DC power fuse. (20-amp fuse on the Norcold's +12VDC "hot" wire out from terminal block).
#11: +12VDC from the TM's converter/regulator. (A dedicated line, with another fuse within the TM's 12V distribution panel.)
#10: -12VDC "neutral". I'll SWAG that this is an actual white wire back to the TM's converter/regulator, but my TM is closed up right now... I'll edit/correct this statement if it turns out to be an adjacent chassis ground.
#4: The selector switch. (With settings for "Off", "DC/Battery", "AC plug-in", and "Propane flame".)
#5: The thermocouple -- which has NOTHING to do with the thermostat. (It is only used for safety and control of gas flow during propane operation.)
#6: the "dumb" thermostat.
#7, #8: propane ignition and flame status devices.
#16: The 12VDC heater (+12V "hot" coming in from terminal "W2" on the selector switch #4; -12V "neutral" straight back to the terminal block).
#17: The 120VAC heater. "Hot" comes on "BLK" from terminal "W1" on selector switch #4, into the "dumb" thermostat #6; when the thermostat feels that the heater circuit should be "on", it connects out on wire "BRN", which is ultimately connected to heater input wire "BLU".)
I'll provide some more diagrams in the next post, but you can already see the Norcold "temperature regulation" problems from my description:
- 12 Volts operation is NOT controlled by the thermostat. You turn the fridge to run on 12V, and it keeps going, and going, and going.... (But unlike the Energizer Bunny, this one hurts batteries.)
- The "dumb" thermostat, controlling AC and Propane, is just like the ones which are used in cheaper, non-digital kitchen refrigerators. But unlike the kitchen refrigerator thermostat, it doesn't sit INSIDE the food storage area. It's sitting on that front control panel, with one side (and the whole dial face) exposed to TM living space. The simple thermometer which is inside of it gets affected, a lot, by temperature changes within the TM living space. There is not a good correlation between "dumb thermostat" temperature and refrigerator interior temperature. That's why it works so badly.
- And finally (as I mentioned in connection with the parts list) the thermocouple has nothing to do with the temperature control thermostat. (It's used for propane control ONLY.)
In the next post, I'll try to explain the flow of electricity (for control and actual heating) in the 3 operating modes.