Furnace not showing as an option on Dometic thermostat

[Brucet45410]

Okay, I took advice from Lewster (He hasn't steered me wrong before) and dropped the lower A/C unit to get to the wiring. I found the RJ-11 connector that Lewster spoke of. BTW, thanks to all the heads up about the hidden screws on the lower unit. There were a total of six screws to get the air distribution box off. Anyway, after resetting the connector a couple of times, resetting the thermostat and attempting to get the Furnace to display, I began to wonder if in fact the thermostat hadn't failed. So I tried to get the Fan to run...Nothing. Then I tried to get the A/C to run...No luck either. Still not showing Furnace as an option.
Battery is showing 100% and everything looked good with power distribution when I tried to get the A/C to come on.
So, I'm believing that the thermostat is in fact the culprit. Does anybody know how to test T-stat to determine if it is faulty?

[Zardoz]

Had the same problem. Learned from a Tech that “Furnace” is only shown while in the Zone 2 mode. Solved my problem.

[HighwayVegan]

Thought we had this fixed a couple weeks back. Started acting up again. The Dometic CCC2 comfort thermostat shows E1 Error code. The thermostat showed no furnace or heat pump available after resetting. Unplugged all power: 30 amp and disconnected main red positive battery cable for 20 minutes as advised. No help! Fixed problem after changing out RJ11 jack underneath inside Heat pump cover. 7 screws to get it off. Had to use flash light as they are not all easy to see. Went to Lowe's and bought a Southwire Networking tool and a pack of RJ-11 6p6c jacks. Looked up YouTube video on wiring RJ11 jack with 4 wires. I cut the existing communication cable ( looks like phone cord and grey) and replaced jack using network tool. The thing I noticed when checking the previous jack, was it was not flush against jack head. I believe that over time it must have wiggled itself out of alignment. Make sure you look at the existing wiring sequence. Make sure you mirror the existing wiring sequence. Since the Jack accepts 6 wires for different connection needs, make sure you only use the center 4. You will not use the outer left/ right contacts. You want everything to match up the same way. Everything is working now. Seems like that must have been the problem. We have a 2015 nineteen foot Bambi Flying Cloud. I have included pictures to help with understanding. Note: RJ11 6p6c is backward compatible to RJ114c. Don't worry. You only need the middle 4 connectors. So basically, cut the grey cord and apply new jacks.

[kscherzi]

That's amazing you figured it out.

[HighwayVegan]

Thank you! Took a couple of days or reading these post and putting some working knowledge together. Had a little help from calling the airstream dealer back home where the unit was purchased. They told me where to access the cable under the heat pump inside. Grateful.

[BayouBiker]

Indeed nice job!


For future readers:

I have come to learn these Dometic heating and cooling systems are great, but they are perhaps overly sensitive to less than ideal wiring and connector condition. Really it is likely due to a trade off between convenience/function, low power consumption, and attempts to make them interface with other manufacturers equipment. In any case when everything is tight, it works great but if the wiring becomes sub-par no end of issues come up.

The most common:

The E1 communications issue which is nearly always an issue with the RJ-11/14 "telephone" cabling. Sometimes it is impedance, neutral voltage imbalances, partial shorts in the control circuits.

Flaky behavior of CCC2 thermostat is generally caused by wiring problems associated with external control and instrumentation wiring.

Furnace issues including furnace running all the time, the 32 degree problem and the furnace not working is generally a problem with the furnace control board on the furnace itself, a furnace fault or the wiring between the furnace and the Dometic control boards.

System reading the wrong settings or system won't run the correct cycle or not detecting the furnace or aqua etc. is generally a configuration problem. Many people have issues when they accidentally set it to run a program or change the config by pushing the wrong combinations of buttons. Keep your manual handy so you can figure out how to recover.

[Pahaska]

The AC in my 2004 25' Airstream trailer kept going to heat pump on its own. It would happen in the middle of the night in mid-summer. The air coming out would literally burn your hand. We travelled with 3 cats and could not trust the AC to leave them unattended, even for a few minutes.

The AC was replaced, twice, and the Dometic thermostat was replaced once. All with no success. It turned out that there was an 18' telephone cable that came with the thermostat and was installed by Airstream with the excess simply wadded up behind the microwave. A 4' cable would have sufficed.

I finally traded that 25' for a 2005 28' at the International rally when the AC had gone to heat pump twice on the trip there. I told the selling dealer about the problem, but since it was still under warranty, I did not lose anything additional on the trade. I never solved the problem, but I think it was caused by a defective microwave, leaking RF into the wadded up unshielded wire. It appeared that the solenoid drivers that change the native heat pump to AC were damaged. The microwave was the only thing not replaced.

Afterwards, I put an RF filter on the telephone cable where it entered the microwave as insurance that it would not happen again. There were no more occurrences in the 2005.

[Hawk-ination]

I was so frustrated with the Dometic control in our 2014.5 Interstate and thankfully someone came on the forum and said they are just a royal pain and don’t work properly a lot of the time. Don’t have answers for your question but made me feel somewhat better it wasn’t operator error. Our 2014 controllers seem to be consistently a problem more over other years, so don’t let anyone make you feel dumb cause they don’t have the same issues we seem to! Just my two cents.

[wwkayaker]

I used the information provided by many concerning resetting the CCC2 to no avail. What finally fixed it was reseating the RJ11 Coupler in the overhead unit per the information provided by HighwayVegan above. You may have to reseat it several times to restore the contact and remove any corrosion...I had to reseat it twice.

Thanks all for your help!!

[Pahaska]

A spray can of contact cleaner goes a long way to solve connection problems.

[Heleenajoy]

My RV has 2 zones. The heater only works downstairs. I don’t have a furnace or heater option on zone 1 (bedroom), only zone 2 (downstairs, living area). A/C does operate in both zones, but not the heater. Once I changed the zone from 1 to 2, the heater option appears and worked just fine on auto mode.

[Fjord F-150]

Hello,

1) I had a new Dometic Penguin 2 installed in July when the AC went out.

2) Did't realize until February that now the furnance does not show up in the themostat settings.

3) I rest the themostat and still not showing up.

4) Several posts reference that the cuase may be the "dip switches" not set correctly.

5) I tool the shroud off.

6) Can anyone point me to the location of the dip switches before I start dissecting more? A few phots are aatched.

Thanks!

[Fjord F-150]

After my last post i was brave and opened up the control box and low and behold the labeled dip switches were there (photos attached). After a few trial and errors the furnace appeared in the thermostat and turned on. Other settings also still appear.

Life is good (and now will be warm!)

[BikeCamper]

Originally Posted by Fjord F-150

After my last post i was brave and opened up the control box and low and behold the labeled dip switches were there (photos attached). After a few trial and errors the furnace appeared in the thermostat and turned on. Other settings also still appear.

Life is good (and now will be warm!)

Well done.

Any chance you could elaborate on the “trial and error” you mentioned, ie what it was in the end that flipped the switch?

Our new-to-us 19’ Flying Cloud has a new Dometic ac & thermostat that does not seem to be recognizing the thermostat….