We don't understand our AC! (T@B 400)

Deb55

This is our first trip in our 2018 T@B 400. There's a lot we're trying to learn! We don't understand the AC. Yesterday, we were gone all day and left the AC running so we could come back to a cool camper. It was freezing! We turned up the temperature on the Dometic to about 75, and at 2:30am, I woke up roasting hot and the inside temp was in the 80s! No AC was running at all. Today, we thought we set it at about 75, and when we came back, it wasn't running and the temp was in the 80s again! We scrolled through every setting on the control panel, and couldn't get it to work. I scrolled through everything again, set the temp to 70, and it mysteriously came on. When it cooled down, we tried to get it to stop, but it wouldn't until we turned the temp on the control up to 85! We're so confused! Adding to this is that for some reason (because I'm short, I think) I can't see the symbols on the screen--it just looks like a blank blue screen. My much taller husband can see all the symbols on the screen just fine. Help us if you can! 

pthomas745

Do you have a manual?  What model is the AC?

Verna

You will need to either get a small folding step stool, or put some spacers behind the top screws holding the thermostat to the cabinet so it is tilted so you can see it from your height. 

As you go through each menu, read the option to make sure it is cooling, not heating. You should have received a manual with your 400’s purchase. The manual does explain what each option performs. 

Deb55

The manual we have, is for installing the AC, not using it. There's a little piece of paper on using it that seems to be for a different model since none of the illustrations on the control match ours. I don't know what model it is. 

Deb55

I just looked at the illustration on the paper that came with the AC, and I think it is the same as ours. We'll try again, but I don't have a stepstool, so my tall husband will have to figure it out, lol! 

Sharon_is_SAM

Does anybody know if the 400 Dometic works off the Alde thermostat or does it have it’s own thermostat?  
Do you need to run the overhead fan to help circulate the air?  
Does it make a difference if the sun hits the door side of the 400 where the thermostat is located?  I would think that may cause the ac to run longer.

DanManz

The Dometic in our 2019 400 has a separate thermostat for the AC (which is really a heat pump).  I'm not sure about your thoughts on the sun hitting the thermostat but it could very well be that it got set to the heat side rather than the cool side.  Deb55 should also be sure the vinyl vent cover on the outside driver/front area is uncovered.  My other observation is that the thermostat on ours takes 15-20 seconds to respond.  Once we make a change in the temp setting, the fan continues to run just as it had been for that brief period until the Dometic perceives the change in setting.

grubbster

One thing I have noticed on this is that you have to have the proper screen showing on the display.  What I mean is that the screen has to be displaying the AC display or it does not cool.  It is easy when making adjustments to be on the heating screen or the fan setting screen when making adjustments and not returning to the AC screen.

Verna

Sharon_is_SAM said:

Does anybody know if the 400 Dometic works off the Alde thermostat or does it have it’s own thermostat?  
Do you need to run the overhead fan to help circulate the air?  
Does it make a difference if the sun hits the door side of the 400 where the thermostat is located?  I would think that may cause the ac to run longer.

The 400 Dometic works off of its own screen and thermostat. There is some difference between the Alde temp shown and the Dometic temp shown, on mine.It actually doesn’t bother me, so it’s just one of those I tolerate. 

atlasb

Also be sure to set the temp on the alde below what the cool cat thermostat is set at.  The are both separate systems and it is possible for the alde to heat at the same time the cool cat is trying to coo.  We usually set the alde to around 60. Degrees or so.  We also find the cool cat cycles quite a bit so we sat the fan on the domestic thermostat to run full time.you do not notice the cool cat cy li g Soo much then.  It has also been me filmed to leave all the windows set on the firstatch position for fresh If intake.

atlasb

Sorry for the typos above.  Big fingers, small keyboard!

pthomas745

I looked all over the Dometic web site last night, and found out what Deb found:  there is no "user" manual, just an "installation" manual. 

Deb55

Thanks everyone! We seem to have figured it out. Once we realized that we need to wait a bit before it responds to requests, it started working for us. I'm also going to buy a small stepstool so I can read what it says! 

Sharon_is_SAM

There is a Dometic thermostat that is bluetooth capable. Maybe that would help - or Verna’s suggestion to tilt it downward😀 

JeffroNC

@Sharon_is_SAM do these work with the Cool Cat in the Tab 400?

Sharon_is_SAM

I think so.  Check it out.

https://www.dometic.com/en-us/us/products/climate/air-conditioners/air-conditioner-accessories/dometic-ct-bluetooth-thermostat-_-164512

Michigan_Mike

I had the factory install my Dometic thermostat lower on the wall for that very reason.  When we run the AC we close the shades to provide some insulation and to ensure adequate cooling.  And agree,  unless you adjust the Alde thermostat you could easily be throwing additional heat into the trailer unknowingly which would defeat your intentions.  

Awca12a

If you look in this manual first, odds are you will have many of your questions about the 400 answered.   Happy 4th

https://tab-rv.vanillacommunity.com/discussion/8650/unofficial-nucamp-t-b400-resource-guide-finalized

davel4wa

Wouldn't it be nice if the Alde controller could integrate control for A/C system as well? Just like your home thermostat it would prevent unintended operation of heating and cooling simultaneously. Plus only one temperature readout to worry about. 
After perusing the Alde website, it appears that the control panel for the 3020 system does incorporate a feature labeled EXT which might be for controlling an external A/C system and also a button labeled AC which might refer to either AC power or air conditioning. The demo if the control panels on their site cleverly simulates operation of the panels but offers no explanation of the functions that are not immediately obvious.