Dometic digital thermostat

[time2roll]

Been wanting to go with a digital thermostat but I was not very excited about using the battery powered home units for the conversion. Then found out Dometic has a new thermostat and control board.

So if you have this thermostat:



And you want something like this:
(I fixed those extra holes BTW)



Here is the kit:

Dometic Single Zone LCD Control Kit w/ Thermostat White 3313189.000 $75

Here is the kit pictured:

clockwise from top left. freeze sensor, spade terminals to crimp onto your furnace control wires, wall thermostat, mounting screws, control box, wire harness.



This is the old box up in the air unit



Here is the new box. Much smaller should also allow better air flow through the inlet filter.



Old box with the gaggle of wires. Actually fairly simple.

Paired white/black are 12v supply.
Blue/white is control connection to furnace.
Yellow is 120v power bundle.
Black to the left is the freeze sensor.
Brown is the bundle from the old thermostat.

Everything is either cut or disconnected to remove the old box.



New box connected to romex



The kit comes with a wire harness to connect to 12v and the thermostat cable. Only three wires are used for the new thermostat. 12+, 12-, & one control wire. I used Red, Black, Orange as that matches the harness.

This is the new box with snap connectors:



The heater control wires connect to the two spade terminals on the left. Thermostat control harness snaps into the four pin middle connector. Freeze sensor on the two pin connector to the right. Romex goes in at the far right. Power and control to the air conditioner uses oem harness that plugs in on the back side.

Worked perfect right out of the box. Well OK I had to buy some spade connectors as the oem wire to the furnace was a larger size. And some crimp connectors (not included) to connect the 12v thermostat harness.

Here is the user manual for those that want more operating details:
Dometic single zone digital operating instructions


Inspired by member BuffaloIndian in this thread:
Anyone Replaced Dometic Thermostat: Analog to Digital?

[time2roll]

Great to hear it worked out well for you :B

[fellow_traveler]

Hi just installed the kit Dometic Single Control Kit LCD Cool Furnace Black Thermostat 3313189.015
Digital Replacement Kit Analog Thermostat 3106995.032 it was a challenge but after talking to my RV dealer mechanic all went well works great now no temp swings in air conditioner or furnace cool pardon my vernacular. the pictures were helpful but I had a question about the 12v + AND 12V- WIRES AS THEY WERE NOT THE SAME COLOR BUT WIRED UP THE SAME AS THE DIAGRAM ALL ELSE WENT WHERE THEY NEEDED TO BE! installed the new freeze sensor all's well here thanks for your post.

[Race_Face]

Thanks to the OP too...

"Quick" weekend trip to San Diego last weekend. Hooked up, heard the humm of AC compressor running (thermostat off) no fan. Manually hit the breaker for the AC. With a high of 75°, didn't need AC. Mobile RV repair was next door, had the tech diagnose bad relay. Got the kit from RV supply place in El Cajon. Took about two hours for me to hook it up. Thanks to the OP for some Picts, just needed clarification since digital used 3 wires and analog took 6.

Works a little different from analog. Takes a few seconds for the AC and heater to respond to commands from thermostat. Where the analog was immediately on or off at the switch on the thermostat.

[EdandLori]

Update: I finally got my new thermostat installed. This post was priceless to help me walk me thru the install. Unit works great and as expected. Install was a breeze thanks to smkettner. One additional piece of advice I can offer .... Don't try to use your existing freeze sensor, even if the connection fits the new control box .... It won't work and generates an error msg on the stat. Took me about 1/2 hour to learn that lesson. 🙂

[EdandLori]

Great. Thanks. I'll let you know how it comes out. Thanks again for the post and checking this out.

[time2roll]

Yes the red/white 12+ is connected only to the thermostat harness to feed 12v+ to the thermostat.

[EdandLori]

smkettner wrote:
Although I think I see the red/white wire in my pic. Maybe I don't recall correctly.
I could swing by storage tomorrow and look at it.

It has been more than a year since I poked at it 😉

Thanks. I plan to install tomorrow(Sunday), so if you get a chance to look at your wiring, let me know. Your pics seem to show the red/white wire as well. Thanks !!!

[time2roll]

Although I think I see the red/white wire in my pic. Maybe I don't recall correctly.
I could swing by storage tomorrow and look at it.

It has been more than a year since I poked at it 😉

[time2roll]

You are correct.

I connected the two B+ from the ceiling to the 12+ (red) from the box together in one crimp.

The red/white wire from the box is connected to the thermostat harness to feed 12v+ to the thermostat.

Sorry for the confusion. I tried to go back and edit my posts.

[EdandLori]

smkettner wrote:
This short description may help with the wiring to the thermostat:

Seemed tricky but it is easy in the end. If you think you will get crossed up then put some tape on your wires to mark them before you cut.

The way mine worked there are two 12+ wires coming from the RV ceiling. These are black as shown in the thread pics. 6th pic I think. These two 12+ wires need to be reconnected to each other and with the 12+ to the box and the 12+ to the thermostat. So 4 wires connected in a bundle for the 12+. The box harness wire is red and is labeled. I connected the red wire in the thermostat bundle to be consistent. Then when you get to the actual thermostat you connect the red wire to the 12+ terminal. Done with 12+.

Similar with 12-. Four wires to connect in the ceiling. The RV 12- are white, box harness is black, I used the black in the thermostat bundle. Then at the thermostat the black is connected to the 12- terminal. Done with 12-.

Last is the signal wire. Just two connect in the ceiling. Box harness is orange so I used the orange wire in the bundle. At the thermostat connect the orange wire to the signal terminal. Done with signal wire.

Color to the thermostat does not particularly matter as long as the 12+, 12-, & signal wire connect same in the ceiling as the thermostat. If you think you might get red/orange mixed up then use green or blue for the signal wire. The unused wires just get folded back out of the way. The replacement is actually a simpler connection than the existing.

Then connect the 120v power, freeze sensor and the heater control wires. Done.

Smkettner: Great post and I am about to install this unit in my TT. You had the same previous control box and stat as I currently have. One question: the wire harness from the new control box has two +12 wires ... One solid Red labeled "+12 from supply" and a second Red/White labeled "+12 To T-stat".

Your wiring description doesn't say what to do with this second Red/white wire from the control wire harness.

Please advise. Thanks.

[time2roll]

oceansailor wrote:
I purchased the same model Dometic T-stat and box for a new A/C unit. Wanted to replace the old analog Duo-term t-stat. However, I do not have wiring to the furnace up by the A/C controller unit. In fact, I wonder how my furnace was controlled...
JP

I am no air conditioner expert but maybe post the model number...

[time2roll]

Seattle Lion wrote:
Our TT is fairly new. Bought it last June. It has a digital thermostat. We have had a big problem with it and with our dealer understanding the problem.

The thermostat seems to "think" it is 10 degrees cooler than it actually is. For example, last summer it was in the 90's outside. We set the thermostat to 70. The AC ran for a while and then the thermostat shut it off. The actual temperature as measured by a digital thermometer was 82 degrees in the TT. I lowered the thermostat to the lowest temp...68 I think...and the AC ran again and once more shut off at 80 deg. The heat mode was similar.

The dealer said the thermostat was ok because the thermometer built in to the thermostat agreed with the setting when heat and ac turned off. I tried to explain that the thermometer in the thermostat was wrong. So frustrating! Obviously, I am not a fan of this thermostat. I would love to replace it.

I think the thermostat is defective or some other issue. Mine holds the temp where it is set.

The digital connection is not compatible with the typical "hunter" replacement.

[oceansailor]

I purchased the same model Dometic T-stat and box for a new A/C unit. Wanted to replace the old analog Duo-term t-stat. However, I do not have wiring to the furnace up by the A/C controller unit. In fact, I wonder how my furnace was controlled...
JP

[Seattle_Lion]

Our TT is fairly new. Bought it last June. It has a digital thermostat. We have had a big problem with it and with our dealer understanding the problem.

The thermostat seems to "think" it is 10 degrees cooler than it actually is. For example, last summer it was in the 90's outside. We set the thermostat to 70. The AC ran for a while and then the thermostat shut it off. The actual temperature as measured by a digital thermometer was 82 degrees in the TT. I lowered the thermostat to the lowest temp...68 I think...and the AC ran again and once more shut off at 80 deg. The heat mode was similar.

The dealer said the thermostat was ok because the thermometer built in to the thermostat agreed with the setting when heat and ac turned off. I tried to explain that the thermometer in the thermostat was wrong. So frustrating! Obviously, I am not a fan of this thermostat. I would love to replace it.

[Seattle_Lion]

Our TT is fairly new. Bought it last June. It has a digital thermostat. We have had a big problem with it and with our dealer understanding the problem.

The thermostat seems to "think" it is 10 degrees cooler than it actually is. For example, last summer it was in the 90's outside. We set the thermostat to 70. The AC ran for a while and then the thermostat shut it off. The actual temperature as measured by a digital thermometer was 82 degrees in the TT. I lowered the thermostat to the lowest temp...68 I think...and the AC ran again and once more shut off at 80 deg. The heat mode was similar.

The dealer said the thermostat was ok because the thermometer built in to the thermostat agreed with the setting when heat and ac turned off. I tried to explain that the thermometer in the thermostat was wrong. So frustrating! Obviously, I am not a fan of this thermostat. I would love to replace it.