Sometimes seemingly simple items can be the most infuriating. One example we hear about frequently is the Dometic digital thermostat that is found in many Airstreams—it has a reputation for being a little cranky.
We're talking about the black or white thermostat that controls your air conditioner, furnace, and heat pump. If you have one, the buttons may be a little different from the one in the picture, but they all work roughly the same. It's officially called the Dometic Comfort Control Center 2 Thermostat, or "CCC2."
The manual that comes with this gizmo says proudly "Your Dometic CCC 2 thermostat has been designed for ease of operation" — which, ironically, is followed by 12 pages of explanation on how to use it.
This thermostat has features laden upon features, enabling control of air conditioner, furnace, heat pump, fans, clock and light. You can program it to change mode and temperature by time of day or depending on temperature, in up to four zones, and in Celsius or Fahrenheit. It even has two different ways to turn it off. The only thing it doesn't do is sing Christmas carols.
This plethora of features creates complexity – which is what can lead to confusion. Let's look at a few of the most common problems that Airstreamers ask us about, and how to fix them.
MODE confusion and what the acronyms mean
Intuitively, you might think a button labeled START would be the first step to use or programming this system. Actually, the MODE button is the key to everything. By pressing MODE, you can toggle through various possible methods of climate control: COOL, FURN, HP, HS, FAN, AUTO, and OFF–although your Airstream may not offer all of these options.
Let's start with the most commonly used modes: air conditioning and furnace.
Push the MODE button, choose the mode you want (COOL = air conditioning, FURN = furnace), then choose the temperature you want using the up and down arrows. Simple enough.
But wait, there's more!
The HP mode is for Heat Pump, which basically means your air conditioner operating in reverse to produce warm air instead of cold. Not all Airstreams have this option. It only works above freezing temps (and not very well below about 40°F), so its use is limited.
If your Airstream doesn't have an HP mode, it might have an HS, which means Heat Strip. A Heat Strip is a little electrical heater built into the air conditioner. Unlike the heat pump, the heat strip works at all temperatures. That's a plus. But since it blows warm air from the ceiling, your feet will still tend to remain cold so bring fuzzy socks if you plan to use the Heat Strip.
FAN mode just makes the fan blow recirculating air without either heat or cooling. It's not very useful. The rooftop Fantastic Vents work a lot better for ventilation.
Finally, there's AUTO mode. This allows you to program the thermostat to run the heat when it's cold in the morning and then switch over to air conditioning when it gets hot. It's a potentially powerful feature but dizzyingly complicated to program. If you don't love technology (or reading detailed instructions), I recommend you steer clear of AUTO mode, and just switch from heating to cooling by yourself.
Ok, I've chosen the mode. What next?
Once you are in any of the modes, pick the fan speed–LOW, MED, HIGH, or AUTO. Do this by poking the FAN button until it displays the speed you want. Honestly, I think it's best to keep things simple and leave the fan set to AUTO. The thermostat will determine a good fan speed, depending on the temperature.
"I set it to 'COOL' but nothing happened..?"
The thermostat won't let the air conditioner turn on for about two minutes after you choose COOL. That's to protect the compressor. So you have to be patient. There's a little hourglass icon in the display that will go away when the air conditioner is ready.
The same is true for HP (heat pump) mode.
"I turned it 'off' but it isn't..?"
The final mode choice is OFF. That's kind of weird, since there's a power button as well. (That's the button on the top left—the one with a circle that has a stem on top.) You'll probably never use OFF mode, unless you are getting fancy with programming (which we'll talk about in a moment).
If your Airstream has two air conditioners, you'll have two zones. Pressing the ZONE button will toggle between Zone 1 and Zone 2. This allows you to run one or both air conditioners, but it can be confusing because the furnace is only in one of those zones. If you can't get to the mode you want, try the other zone.
If you had two zones that displayed, but suddenly only have one, check the power coming into the trailer. If the 50-amp power isn't wired correctly, or you are plugged into a 30-amp outlet, one of the zones will be unavailable.
In other words, you must be connected to 50-amp power to cool both Zone 1 and Zone 2 simultaneously.
And yes, you can set the temperature in each zone separately. You can even run the heat in one zone and the air conditioning in the other, although it doesn't really make sense to have such a feature in a 200 square foot space.
There's a page in the Dometic manual that describes all the error messages, but the most common one is an “E7” error code. This code simply means that the thermostat was set to run the air conditioning (or heat pump) but couldn’t. Usually it is because there was no AC power to the Airstream. To fix this: plug in the Airstream (or reset the circuit breaker if it popped off) then power the thermostat off and on to reset it.
Stuck in programming purgatory?
If you find, as occasionally happens, that none of the buttons are working as expected, you may have accidentally entered "program mode." You'll know you are in program mode if "PROG 1" or "PROG 2" is blinking in the display. To get out of this mode, push and hold the PROGRAM button for 3 seconds and it will go back to normal. Consider this your get-out-of-purgatory free card.
Really, really stuck?
Nothing in this blog post seem to solve your problem? Thermostat still misbehaving? You can assert your superiority over this little plastic martinet by forcing a total reboot.
The secret to showing your defiant digital helper who's boss is to press and hold the MODE and ZONE buttons simultaneously. When the display shows "IniT" you can release the buttons. Then press the Power button.
Now that you've tamed the unit into submission, press MODE to start all over again.
Finally, if you really hate the Dometic thermostat, there's an easier alternative. Check out the Micro-Air EasyTouch thermostat, as recommended by many of our readers below.