Best Replacement For Older Dometic Duo Therm 57915.531 Ducted Single Zone AC System With Furnace

Updated 03/05/2026 | Published 02/25/2026

Question:

I am looking to replace an older dometic duotherm 57915.531. It is a ducted single zone with furnace . What do you recommend to replace. I am not hearing good things about the Fresh jet or advent. Would really like a Penguin II but know its not plug and play and would require refitting the whole thing.

asked by: Ray

Expert Reply:

Hey Ray, thanks for reaching out. Yes we do have a good option for replacing your Dometic Duo-Therm 57915.531. With yours being an older unit, there is not a direct rooftop swap that keeps your existing controls. The correct path is replacing the rooftop unit along with the air distribution box and thermostat, so the system is matched and fully compatible.

For that, I recommend the following:

- Furrion Chill Cube RV AC w Air Distribution Box, Thermostat - Ducted - 18,000 Btu - White # FR69AD

This 18K BTU system is designed with lower startup and amp draw than many traditional 13.5K or 15K units. It works with a ducted configuration, and the included thermostat controls both the AC and your furnace. It also comes with a handheld remote for added convenience.

This setup gives you a modern, fully integrated system that cools efficiently and removes compatibility guesswork. Will definitely make those summer trips more comfortable.

What kind of RV do you have?

expert reply by: Jesse M

Furrion Chill Cube RV AC w Air Distribution Box, Thermostat - Ducted - 18,000 Btu - White
(click to enlarge)

Ray

2/26/2026

Is the 15000btu compatible with furnace connection. Have a rear ac that is still working. 18000 feels like overkill.

Jesse M.

2/27/2026

@Ray Hey Ray, yes that makes sense. The 15K BTU is absolutely an option as well. For that I recommend the following: - Furrion Chill HE RV Air Conditioner System - Single Zone - 15,000 Btu - White - R32 # FR83TD

Ray

2/27/2026

@JesseM Just FYI the furnace is wired to the broken ac in front not the rear ac that is still cooling. So this ac you are recommending has the wiring for the furnace?

Jesse M.

3/2/2026

@Ray It would use the current furnace wiring. It does not come with new furnace wiring.

Ray

2/26/2026

Which model would work 13500 or or 15000 in our situation with furnace wiring

Jesse M.

2/27/2026

@Ray You could do a 13K or 15K BTU I just typically recommend going with the higher number because it'll cool more effectively. They both use the same thermostat, and it can control AC and furnace.

Ray

3/5/2026

@JesseMWexwere all set to go with the Furrion but after much research we found out the the thermostat dies not have the thermistor in the actual thermostat to detect room temperature, but it's located in the plenum area causing the unit to not cool properly and that the newer thermostat has an upgrade but for furnace only. We want a thermostat to read room temp not the air in distribution box. Very dumb design by Furrion, does not make sense to change what has been a reliable technology.

Jesse M.

3/5/2026

@Ray Hey Ray yes the temp sensor is in the distribution box and I can see how that might change the way the system cools. They did change several things about their design when they switched to the R32 refrigerant so it might have had something to do with that.