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Old 05-15-2024, 11:02 AM   #1
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Join Date: Sep 2019
Location: Hill AFB
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M.O.C. #24919
Domestic CT Thermostat hysteresis

I searched, but didn't find anything.
I have been having concerns about the bedroom A/C and it not turning on until it is too hot inside. I checked the actual temp on the thermostat and it showed in the 80s even though the setpoint was 74. We are full time and this is not satisfactory
I thought it was just broken and needed replacement.
Then, I wrote to Dometic and got this response:
"The CT thermostat system does not have differential setting to be changed for activation of cool mode. The 4 degree swing in temperature prior to system activating fan and compressor is system design. We actually allow a 7 degree swing on thermostat system."

7 DEGREES! You gotten be KIDDING ME! No wonder it gets hot, then gets cold back and forth. Home thermostats are have a much narrower range for activation.

I have already replaced the main A/C thermostat with an EasyTouch with adjustable hysteresis, but those are so expensive. It works great!

Has anyone figured out how to modify the CT thermostat, or how to easily replace it with a house thermostat? I've seen the analog versions can be replaced with some Honeywell battery powered units...

This is frustrating.
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Old 05-15-2024, 03:03 PM   #2
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Location: Austin
Posts: 2,483
M.O.C. #21044
Save up your money and buy a MicroAir thermostat and throw the Dometic in the trash.
MikenDebbie Aggie ‘77 in the sticks near Austin TX
2019 Chevy 3500 High Country DRW
2018 Montana 3921FB
Aussie Gus + Texas Heeler Jimmy
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Old 05-15-2024, 03:59 PM   #3
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Location: Alton
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M.O.C. #24086
This guy installed a battery powered one. He says it also worked on the RV 12vdc system.

AC thermostat (battery)

EconoHome Non-Programmable Thermostat for Home - Heat & Cooling Temperature Control - Easy to Install - Digital Thermostat for Central Gas, Oil, Electric Furnaces, Single Stage Systems
Daryl and Marianne,
2019 3130re 20th Anniversary Edition
2016 F350 Lariat
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Old 05-21-2024, 12:04 PM   #4
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Location: Oklahoma City
Posts: 178
M.O.C. #23433
The Micro Air thermostat has a fully customizable hysteresis setting. We have ours adjusted to 3 degrees for heat and AC.
Troy and Tracy Chaddon
2019 Montana High Country 330RL
2005 Ford F-350 "Bulletproofed"
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Old 05-21-2024, 12:14 PM   #5
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M.O.C. #24919
Thanks everyone, I went ahead and bit the bullet and bought another MicroAire.

It appears the proprietary system that Dometic uses is not compatible with and DIY efforts using an battery powered off the shelf household thermostat and this was the only alternative.
2016 3000RE
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