Looking To Replace Dometic Duo Therm 991721729 AC Unit

Updated 03/24/2026 | Published 03/17/2026

Question:

Hi I’m looking to replace my domestic duo therm 991721729 air conditioner do you know what unit replaces this?

asked by: Austin M

Expert Reply:

Hello Austin, thanks for reaching out. We can help you replace your Dometic duo therm 991721729 AC unit. With that older Dometic Duo-Therm 991721729, there unfortunately isn’t a true plug-and-play replacement anymore. At this point it’s a full system swap, meaning the rooftop unit, ceiling assembly, and thermostat all get updated together. The upside is once it’s done, you’re not dealing with mismatched components or chasing compatibility issues later.

That said, here’s what I’d recommend:

Advent Air RV Air Conditioner System - Single Zone - 15,000 Btu - White - R32 # ADV92SR

This gives you a complete, matched system out of the box so everything works together the way it should. The 15K BTU output is solid, so you’ll have no problem keeping things cool, and airflow is typically better than the older units. It’s designed to work with both ducted and non-ducted setups, so it keeps things flexible depending on how your current system is set up.

As far as install goes, it still uses the standard 14x14 roof opening, so you’re not cutting into the roof or doing anything crazy there. Most of the work is just swapping components and tying into your existing 120V power.

End result, you go from an aging setup with limited support to a clean, reliable system you can count on when it’s hot out, without having to second guess it later.

What RV do you have? Where are you headed after you get the AC up and running?

expert reply by: Jesse M

Advent Air RV Air Conditioner System - Single Zone - 15,000 Btu - White - R32
(click to enlarge)

Austin M.

3/18/2026

So what thermostat and I would need to replace both units correct?

Jesse M.

3/18/2026

@AustinM The # ADV92SR kit includes a thermostat, so that is what you would want to use. Yes you will want to replace both units. Are they currently both set up to run off the same thermostat, or do you have two separate thermostats?

Austin M.

3/18/2026

@JesseM they are on the same one

Jesse M.

3/18/2026

@AustinM Ok gotcha. That Advent unit I mentioned is single zone only so we will need to go in a different direction unless you want to install and wire in a second thermostat. For a multi zone setup, the Furrion Chill HE # FR73TD is what I recommend. It comes with a multi zone controller and thermostat. Then you can add a second unit with parts # FR86TD and FR68TD. These will also work with both ducted and ductless systems. It is also heat strip compatible if you wanted to add that ever.