How to Wire a Furnace to the Air Distribution Box w/ Wall-Mounted Thermostat for Advent AC

Updated 01/19/2026 | Published 12/03/2025

Question:

Awhile back I bought an Advent low profile white 15,000 Btu AC. I followed your installation video. great video My AC works great. But when I tried to turn on the heat furnace on the new thermostat It wouldnt go to heat, only would go from air cool to fan and back to air. After following the video, all wires were hooked up except one marked heater from the unit and one brown two wire from the trailer. I figured it must be from the furnace. I paired the brown to the unit heat wire and the white to a common ground. What did I do wrong?

asked by: curtis w

Expert Reply:

Hey Curtis, welcome back. To connect a furnace to the Air Distribution Box w/ Wall-Mounted Thermostat for Advent Air RV Air Conditioners - White - R32 item # ADV98SR, you'll need to connect the control box's red and ground wires to a 12-volt power source and the brown/white furnace wire to the control box's "Tstat" bundle, specifically to the wire that goes back to the furnace. Then, connect the thermostat bundle wires to the thermostat and set the furnace option dip switch (usually #3) to the "up" position.

expert reply by: Jerred H

Curtis

12/8/2025

thanks for your answer. it wasn't the wiring, it was the switch, the installation video didn't mention it

Jerred H.

12/8/2025

@Curtis You're welcome! Glad you got it up and running!

Tony

1/19/2026

@JerredH I'm in a similar situation. I replaced a dometic control box with this one from Advent. I have 1 red and 1 white wire coming from furnace (very thin, like thermostat wire) that plugged directly into old control box and heavier gauge brown / white wire marked "to furnace (12 vdc)" coming from new control box. I'm not sure which wires go where, any help is appreciated. All other wiring matched up and a/c works as it should.