The current flow diagram, from the Service Manual, is attached. The large box, #17, is the selector switch. The AC heater is shown as #4; the DC heater is shown as #14. The AC "hot" connection through the Thermostat is at #3. (I have no idea why it is shown with this symbol; it functions as a simple on/off switch in this case.) And the group of components at the lower left, #6-7-8-11, is the Propane control section. (#6 is the gas safety valve; #7 is the thermocouple interrupter; #8 is the front-panel flame meter; and #11 is the thermocouple.) I see that the flame meter "red" wire goes into the thermostat in order to complete a grounding connection, and although their picture shows no thermostat involvement in Propane mode, I think that the thermostat's dial setting
does have an effect here.
DC Operating Mode
Norcold specified the operating limits of DC mode at 13.5 Volts minimum, 15.4 Volts maximum. But there's nothing to interrupt or test the voltage along the DC current path; once it's running, it will happily suck your TM and TV batteries down to the point where your TV needs a "jump" in order to restart the vehicle. (As so many have learned, the hard way...
) Current and heater power are voltage dependent. At 14.0 volts, output is 150 watts and current is 10.7 Amps. At higher voltage, more current goes through the heater, and output is higher.
This mode corresponds to the current path #12 (+12VDC) --> #13 (DC fuse) --> selector switch --> DC heater #14 --> Grounding Connection #15. Why this picture uses totally different numbers, I have no idea.
The real numbers, so that you can match up with the diagram in post #1, are as follows: #11 (+12VDC) --> #12 (fuse, same number) --> selector switch #4 --> DC heater #16 (
different number!) --> Grounding connection # 10.
The big surprise here is the fact that both diagrams agree: DC operating mode never goes through the "dumb" thermostat for any management. There's simply no control connection, in or out, along this path. (hmmmm, I'm not impressed.... and don't let me get started on their use of a WHITE!!! wire for the
HOT DC connection through the fuse and into the selector switch.)
AC Operating Mode
This is the top diagram, shown as #1, 120VAC "hot"; --> #2, AC Fuse; --> selector switch; --> #3, rotary "dumb" thermostat; --> #4, AC Heater; goes to #5, neutral wire into the AC plug. The padt numbers which changed are #2, the AC fuse (#3 in the previous diagram); #3, the "dumb" thermostat (formerly labeled as #6); the AC Heater (formerly labeled as #9); and the neutral connection back to the AC power distribution panel (not previously numbered separately.)
No surprises here, it's exactly as I had expected to see.
Propane Operating Mode
This is all a mystery to me, and I'm not going to touch
anything involved in the regulation of this mode. I'm only going after the DC and AC circuits....