Hey, Dave,
I was hooked up to shore power in my 2016 Airstream Interstate 24GT. While changing the mode at the Dometic 10-button A/C thermostat control panel, it suddenly lost power. The panel is completely dead. I checked the breakers and fuses in the distribution center and they were all good. I removed the thermostat to check for power to the unit with a multimeter, but it has a phone-type jack. The A/C is totally dead. Is it possible that the thermostat panel is blown, or is there somewhere else I can check breakers or fuses? Please help. Thanks. —James, 2016 Airstream Interstate 24GT
Hey, James,
There seems to be quite a track record of failures on these Dometic thermostats. The fancier components get and the more functions they attempt to control, the more they fail with the banging down the road and temperature changes inside the rigs.
The phone line goes from the thermostat to the control board up on the roof air conditioner. It provides 12-volt power to the thermostat and you can verify power by using a multimeter on the red and black wire. You should find 12.6 volts there.
Check the control panel
Another area to check is the control panel at the roof air conditioner, which also has a 12-volt fuse. Remove the return air cover plate and there should be a wire going into a metal covered box. Make sure the unit is not plugged in and the negative battery cable is disconnected so there is no power going to the roof air conditioner. You should then be able to check the fuse for continuity.
Another issue could be moisture in the plugs and jacks, which can be treated with an electrical cleaner such as DeoxIT®. Check and clean all the connections, especially if there is a junction plug. I found a bad connector in the 2016 Thor Challenger we were working on that had a phone line running from the inverter to the inside display panel. The ends were fine; however, the cheap little connector had failed. What a pain!
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Dometic A/C keeps changing fan speeds. Why?
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My RV’s main Dometic A/C unit will sometimes keep changing fan speeds. It sounds like the compressor hesitates and starts with the fan speed being higher or lower. This will continue for some time, or I can raise the thermostat temp to stop it. Is this normal or could it be a bad thermostat? The internet has all kinds of misinformation. —Carl, Keystone Cougar MKS333
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Why any company would use an RJ type plug is beyond me. They are limited to 1.5 amps. Plus, the small ‘terminals’ just pierce the insulation on the wire, not a solid connection. The wire size is either 22 or 24 gauge, good for less than 1 amp.
You can get a double female RG11 jack at the hardware store. Then plug another short RG11 patch cord into that, cut the other RG11 plug off and strip the individual red and black conductor to bare then hit it with the volt meter.
Thank you, Dave! 🙂 I appreciate the thoroughness of your answers, not just today but every day. 🙂 Thank you! 🙂
I do my best to avoid Dometic products. They don’t seem to last long without problems.