If you have the 7-day timer, there is no dash switch for the Aux Heater ... just punch the red button on the timer.
That turns it on for 2 hours.
At the end of the 2 hours you can punch the button again.
For people
without the 7-day timer, there is a toggle on the dash (for which i can't find the part number)
Here's what it looks like:
And the schematic shows it to be a simple single-pole, single-throw non-momentary switch, but with the tally LED between the switched side of the circuit and ground:
I don't know if the "rear blower switch" (
https://www.moparpartsgiant.com/parts/mopar-switch-rear-blower~5103853aa.html) suggested earlier has the tally light.
The manual shows that "underscore" under the wavy lines, which hints that the blower switch may differ.
--dick