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Old 10-22-2020, 09:18 AM   #1
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Dometic Digital Thermostat issues.

I've got three Dometic Brisk II AC units on my camper. Two of them have identical Dometic digital thermostats.
The thermostat on the rear-most unit has had a super-dim display since new. I mean, the backlight is bright but the digits are really hard to see. Oddly - I can see the digits perfectly clearly till the backlight comes on. Over the time I've been dealing with this I've learned that if I shine a flashlight from the side I can at least read the display well enough to change the settings with the backlight on.

So, I ordered a new thermostat thinking I just had a bad one...installed it and am getting the same issue with the new one. It may be slightly easier to read but not much.
At this point I don't know if I've got two thermostats from a bad batch or if there is something going on with the unit itself that causes this. I guess I can swap the known good working one on one of the other AC units to see if the problem stays but thought I would ask here first. The wiring between the thermostat and that unit is problably the shortest run of the two with thermostats so I don't think the wire length is causing too much power-loss.

As as side note: The center AC unit(ducted) has been replaced under Dometic warranty three times now when each stopped cooling(obviously a leak). The current one cools fine but has a squeeking noise from one of the internal fans - I'm going to have to track down. That thermostat has always worked fine though. I really have been unhappy with Dometic. The last two times I had to pay for most of the labor. This camper is only two years old.

Does anyone have any thoughts? Also, if anyone has access to detailed electronic schematics for these units or other information not found in the installation/owners docs I would love to have a copy. I'd like to maybe create my own thermostat system for these but don't know what communications are involved over the one dataline to the AC unit itself. The other connections are obviously just 12vdc power/ground.

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Old 10-22-2020, 12:02 PM   #2
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The TS you have (3 wire digital) is a direct replacement for one of these and some have gone back to their original. It is easier to read for those with difficulty reading the kind you have. This TS is of course available with whatever functions your existing TS has. It uses tactile switching instead of capacitive touch. Just a thought.
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Old 10-22-2020, 12:22 PM   #3
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Have you checked the 12 volts at the thermostat to make sure it's actually 12 volts?
Since two units have done the same thing I would suspect low voltage.
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Old 10-22-2020, 12:34 PM   #4
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Voltage

Thanks for the reply - getting 11.85vdc at the terminals.

Quote:
Originally Posted by Bama Rambler View Post
Have you checked the 12 volts at the thermostat to make sure it's actually 12 volts?
Since two units have done the same thing I would suspect low voltage.
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Old 10-22-2020, 12:35 PM   #5
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Replacement

Hey that looks like a good option...Wasn't sure they were interchangeable. Thanks!

Quote:
Originally Posted by bubbles View Post
The TS you have (3 wire digital) is a direct replacement for one of these and some have gone back to their original. It is easier to read for those with difficulty reading the kind you have. This TS is of course available with whatever functions your existing TS has. It uses tactile switching instead of capacitive touch. Just a thought.
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Old 10-23-2020, 06:17 PM   #6
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LCD viewing angle

One characteristic of LCD displays is that viewing angle is related to bias voltage. Have you tried looking up at the unit from below? Or down from above?
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