Upgrading from 13,000 BTU A/C to 15,000 BTU Coleman-Mach Roughneck A/C
Updated 04/15/2026 | Published 04/05/2026
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Question:
Hello, I have a dometic rooftop manual 13,500 btu ac B57915.711. 2018 coleman lantern 274bhs. Im guessing about 230sf. The 13,500 btu did cool enough during the Texas heat. Am I able to upgrade to a 15,000 btu in yalls brand without hurting the power, tripping breakers and still will be able to use my Westinghouse 4500w peak power/3700 running power generator when power goes out. The ac never shuts off. Do any rooftops kick on and off when set to temperatures. I think it would cost more to try and fix the one I have now. It just humms when turned on. Doest blow any air either. When it did blow air it was hot air before it completely shut down. Hope all of that makes sense lol. Would like one that tured off and on to set temperature if that is possible. Idk if it is or not. Kinda newish to the camper as units. Thank yall for any help.
asked by: Clinton
Expert Reply:
This all makes perfect sense Clinton, and you gave really good detail.
Here's the good news, you can absolutely upgrade from your 13k BTU unit to a 15k BTU unit with no issues. Both sizes use the same standard roof opening, so it’s a straightforward swap. Moving up to a 15K BTU will give you that extra cooling, especially in high heat.
Coleman-Mach Roughneck Mach 15 ducted # CM75RR
Coleman-Mach Roughneck Mach 15 ductless # CM28RR
As for your Westinghouse generator, it's in a good range to handle a 15K unit. There will be a small increase in power draw with the upgrade, just be conscious of what's using power while using your AC. AC units draw more electricity when they first kick on. To make sure everything runs smoothly and to help prevent breaker trips, we recommend adding the # 1497-3601 Coleman Mach RV AC Soft Start Kit. This will reduce the startup surge significantly, making it much easier for your generator to handle the load and improving overall performance.
You mentioned your current AC is running nonstop, that’s likely due to a manual control setup. If you upgrade to a unit with a compatible thermostat, you’ll be able to set your desired temperature and have the AC cycle on and off automatically.
Are you trying to keep it cool all day or mainly at night?
Clinton
4/10/2026
I seen lots of units on yalls site for 700 to 1000 dollars. Will they not work for what i need. Thank you
James D.
4/10/2026
Wayne S.
4/11/2026
I upgraded from a Coleman 13,500 to the Advent 15,000 and it worked great. We get pretty warm in Eastern Washington. 100 plus a lot of the time. I have a 28 foot travel trailer with a single unit and the unit runs non stop when it's that hot. I'm usually on shore power but my 3500 watt generator handles it fine also. So far no problems. You definitely want the soft start with a generator.
Product Page this Question was Asked From
Advent Air RV AC System w/ Wall Thermostat - 15,000 Btu - Ducted/Non-Ducted - White - R32
- RV Air Conditioners
- Complete AC System
- Cool Only
- 15000 Btu
- Standard Height
- Single Zone
- Rooftop
- Ducted
- Non-Ducted
- White
- Advent Air
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Clinton
4/10/2026
Thank you, I would be keeping it cool all day for my dogs. I would like to stay around 1,000 dollars if possible even with the soft start a thermostat wall unit. How much harder is it to install the thermostat wall unit. If you can list all units if possible that fit my price range. I will be changing out the unit myself but we'll probably have to have a technician install the thermostat wall unit. Thank you for all the help....