This is a wiring question related to a thermostat upgrade.
I've upgraded from the manual control ceiling assembly on my stock GE rooftop AC to a wall-thermostat-controlled assembly (details below). The upgrade is working really well for AC control. However, the upgrade is meant to control of the furnace, as well. But the furnace isn't coming on. I need some help figuring this out.
The details:
My stock 2021 Keystone Bullet Crossfire 2200BH came with a Dometic furnace, controlled with the simplest of wall thermostats:
and the dumb manual ceiling controls (GE RARMN1A) for the AC:
But GE (Camping World) offers a wall thermostat upgrade kit for the AC unit, and the thermostat also supports a separate furnace. (Model numbers RAREN1A Non-Ducted Ceiling Assembly, the RARMC2A Control Box, and the RARWT2B Black Thermostat)
I couldn't find an installation video for exactly my use case, but found two great ones from GE for the very similar ducted version: "Installing the RARED1A"
and "Upgrading your existing RVAC with a GE..."
Following a mix of these instructions, everything went fairly well. The GE wall thermostat is controlling the roof AC unit properly. But the furnace isn't coming on when it should.
I removed the very simple Dometic furnace thermostat and ran the two wires from the back of it to the RARMC2A control box, instead. The first video suggests all I have to do is run those two wires to the two Blue/White wires of the RARMC2A. The second video suggests it is important to also splice 12V+ into one of those wires. I've tried both wiring options (with and without the 12V), but neither seems to activate the furnace.
So, two questions, 1) should 12V+ be spliced into one of the furnace wire-to-blue/white wires or not? and 2) what am I missing? What might cause the AC portion to work well, but the furnace control not to work? Thanks.