Neil (or anyone else who wishes to chime in with expertise):

Okay, so I borrowed a multimeter and set it to AC 200 and started
checking the wiring on top of my Dometic.

And just to remind everyone of my problem, my Dometic 120v power
source isn't creating any heat.

Here is what I found out:

I set the three-way switch to plug in power and plugged the Dometic
into my household 120 outlet.

1) When I complete the circuit using the black wire that leaves the
three-way switch and enter the main screw and plastic connectors
(using the green ground on the back edge to complete the circuit) I
get a reading of 119.2-7 volts, as one might expect.

2) When I complete a circuit using the insulated wire leaving the
plastic connectors and leading to the 120v heater rod, and touch the
probe to the same colored wire coming back into the plastic coupler, I
get an identical voltage reading. (I'm bypassing the heater rod
altogether.)

         and,

3) When I complete the circuit using the first insulated wire, and
then complete the circuit by touching the probe to the outer sleeve of
the 120v heater rod I get the IDENTICAL voltage reading again. (but
with a more varied fluctuation.)

So I assume then, that there is, in fact, 110-120v power flowing
through the 120v heating loop when the fridge is plugged in and the
switch is set.

So why isn't the 120v heater rod getting hot then? Is there a
thermostat or coupler somewhere that is preventing this? Or something
else altogether? My Dometic has been plugged in for days with the door
off.

Any ideas?

Disclaimer: I'm not an electrician but I play one on TV.

TIA,

Thomas