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Old 02-24-2021, 06:05 PM   #1
jcclaus
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Thermostat issue

We're parked at home but want the furnace to keep the fiver slightly warm. But, the CCC2 thermostat is blank. Checked fuses. Tried a new replacement thermostat but nothing. Wiring to the CCC2 looks like a telephone jack. Have tried to trace but it disappears into the ceiling and can't find where the other end of the "telephone line" is. 2014 3155RL. ANY IDEAS?
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Old 02-24-2021, 06:29 PM   #2
Carl n Susan
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I believe the other end of the Phone Line is in the Air Conditioner. While the "phone line" is similar looking to your land line one, I thing the wiring is reversed at one end. But is a while since I messed with one.



Have you tried a "Reset"
To do a system reset:
1. Make sure the CCC 2 thermostat is in the OFF mode.
2. Simultaneously press the MODE and ZONE buttons. The LCD will display “IniT”
and all available zones.
3. Release the MODE and ZONE buttons.
4. Press the ON/OFF button to exit system set up.


There are a couple of manuals for the CCC2 is you Google "dometic ccc2"
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Old 02-24-2021, 08:11 PM   #3
jcclaus
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Yep....tried the reset....can't figure out the route for power to the themostat......is it from the fuse panel to the furnace to the AC to the thermostat?
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Old 02-24-2021, 09:24 PM   #4
Carl n Susan
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The thermostat gets its power from the A/C unit according to the installation manual.
https://www.google.com/url?sa=t&rct=...pG4EbXSnIx8Dp-
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Old 02-24-2021, 09:41 PM   #5
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This doesn't matter if you have one or two A/C units, but the phone type cable will go from the thermostat to the rear A/C unit, probably your rear unit will be a 15K A/C. The cable goes to the control box mounted just above the filter, and possibly you might have corrosion which will prevent power getting to your thermostat. To access the box, you will probably have to remove the entire ceiling filter cover. We had corrosion a number of years ago in our front A/C control box and I replaced it. The photo is of the circuit board, which has the jacks that the phone type cables plug into, at the top of the photo. If you have a second A/C, you should see two cables plugged into those jacks, one from the thermostat and the other going to the front A/C. There will be a box under each A/C unit. There will also be wiring to that box from the furnace. This is the box that the thermostat talks to: https://www.amazon.com/Dometic-33120.../dp/B00HSO05R4
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Old 02-24-2021, 09:55 PM   #6
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THANKS .....to you both for getting me off dead center...the search continues tomorrow. I wonder which is which
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Old 02-27-2021, 09:54 AM   #7
ChuckS
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Id pull the CCC2 off the wall and measure for 12 volts DC on the red and black wire of the telephone lead... This is the 12 volts DC supply coming from Zone 1 gateway and or control module on the roof AC unit...

If you have no 12 volts present at the thermostat then measure for 12 volts at the end that plugs into gateway (red/Black)... if power is present there then you have a break in the telephone cable somewhere...

The other two leads in that 4 wire line are for the CANBUS to communicate from Tstat to furnace and AC units

NOTE.. 12 volts DC power is always present on that telephone line whether on shore power or batteries


Should take about 15 minutes ti find your problem using a multimeter
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Old 02-27-2021, 10:01 AM   #8
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General diagram... the 12 volts DC source up to the Zone 1 unit is usually piggy backed off a 12 volt circuit in the power center and will most likely not be labeled to identify which one...
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Old 02-27-2021, 11:15 AM   #9
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This would only be on the Dometic systems with the CCC2 thermostats, not the Duo-Therm.
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Old 02-27-2021, 11:20 AM   #10
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Quote:
Originally Posted by rohrmann View Post
This would only be on the Dometic systems with the CCC2 thermostats, not the Duo-Therm.
OP stated he is using the CCC2 thermostat..
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Old 02-27-2021, 09:09 PM   #11
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I realize that, but the previous post included a diagram for the Duo-Therm, which does not apply.
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Old 03-04-2021, 08:41 AM   #12
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Thanks to all.....traced the power failure to the rear A/C power control circuit board,.....surrendered ....and towed to a Dometic service dealer.
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