Dometic AC controller

I have posted previously about the position of the ac thermostat mounted near the door. Gets hot there so ac runs way too cold.
My options are to move the unit or replace with a suitable controller which has a remote sensor. Anyone got experience of this?
Just increasing the thermostat setting is not consistent. If the sun is not pointing at the door it works fine. So during the day the temperature would vary wildly. For instance at my last camp, the ac ran continuously although set to 80 and the trailer was freezing. However at night to get a reasonsble temperature 73 was great and the ac cycled correctly.
I have reached out to Dometic, but no answer yet.

Comments

  • Michigan_MikeMichigan_Mike Administrator Posts: 2,830
    edited July 2019
    When we run the AC we pull the shade on the door, pull the window shades down to eliminate sun and heat from entering our 400 and allow the trailer a quicker means of cooling down on hot days.  The inside wall where the thermostat is mounted doesn’t conduct heat but could receive some influence by the exterior wall, but we haven’t noticed the differential as you have noted above.  

    Maybe your real issue is a defective thermostat?  If your AC is running non-stop and doesn’t cycle off when the interior temperature hits 80° then something is amiss.  The AC unit should cycle and shut off when it reaches the desired cooling temperature and if not, true using a separate thermometer to verify what the actual cabin temperature is as your AC thermostat control module might just be defective?   I use a visor and awning on our trailer too when wind speeds allow for setup and depending on the length of our stay when traveling. 

    One other thing to do to do is check your thermostat and make sure you are not running the unit full-time in the “fan” mode.  It’s easy to hit that icon and that will run the AC unit continuously and it will not cycle on and off as it is designed to do.  I suspect that that is your real issue here, as if you cannot easily view the thermostat it would be easy enough to accidentally have it set to the fan mode and allow the unit to run nonstop.  👍🏻
    Mike 
    Howell, Mi
    2019 [email protected] 400
    2021 Chevy Silverado LTZ
  • Tundra57Tundra57 Member Posts: 640
    I will check that. But as i remember it was set to fan auto. As i also mentioned later in the day when the sun was not on that side it worked fine and cycled correctly. So i think the stat is ok. I do shut all the curtains on that side and the door blind. If you touched the wood the stat was mounted on it was warm. On the opposite site there is a vent. Next time ill angle that to blow accross toward the thermostat. I contacted Dometic 4 days ago but no answer yet. I purchased a walker awning but its quite a task to put it up so since it was only a 3 day camp i left it in the truck. I also could be more selective in where i chose to camp. In this case it was an end site and it was easier and more level to park sideways. But if I had parked parallel only the front of the trailer would have been in full sun. That should have helped. Thanks for your suggestions. Just an fyi, I saw a thread which said there was no drain in the pan of the ac unit. Mine has one, its a very late 2019 model ie December 2018.
  • dnordahl1dnordahl1 Member Posts: 5
    edited June 23
    I find it really puzzling that more people have not posted any ideas of how to fix this issue.  The thermostat placements next to the door is by far the most annoying design issue with my 2019 [email protected]  It gets really old adjusting the thermostat setting a dozen times a day depending on the outdoor temp and the sun's orientation on the door side of the trailer.

    And now I just took the cover off of the dometic thermostat to see if there is any plug for a remote sensor inside, and when I put place it back on the buttons don't work.  I'm extremely tired of everything made by dometic/jensen/fantasticfan/camco.  I've been systematically removing and replacing every instance of products made by any of these companies where ever possible.  I've been scouring these forums for a while, on solutions or alternatives to the dometic thermostat location and quality issues (or even just something with bluetooth).  I was happy to discover advice regarding a remote sensor thermostat available for the Alde thermostat as a way to address the same problems I experience with the poor location of the Alde thermostat during the winter.  But I'm really confounded how for all the countless involved modifications, upgrades, and fixes described on this forum for TAB trailers.. there really seems to be no alternative offered for this piece of junk dometic thermostat for the cool cat AC, or at the very least any suggestions for how to improve the temp reading fluctuations it gives.  I would think that being housed against the microwave cabinet enclosure (which seems to have no ventilation and which probably collects heat from the exterior wall) is a contributor to the problem (in addition to being right next to the door). 

    So any ideas why the buttons don't work on my thermostat after simply removing the cover?  The little foam things are all still positioned in the holes behind the buttons and remain there when I place the cover back on.  Is there some sort of conductive goop that the foam bits hold which allows the buttons to function correctly on the face plate? 

    2019 Nucamp Tab 400, 2007 Toyota Tundra 4.7L, 4wd SR5

  • dnordahl1dnordahl1 Member Posts: 5
    edited June 23
    Just to update.. I did manage to get the buttons working on the dometic thermostat again by pulling the fuse, then putting the face back on, and the plugging the fuse back in. 

    I think when I have some time, I'm going to try insulating/filling the hole behind the thermostat, and then putting some spacers behind it's housing so that there's some airflow possible between the thermostat and the kitchen cabinetry which I suspect is responsible for conducting a lot of built up heat to the thermostat.
    2019 Nucamp Tab 400, 2007 Toyota Tundra 4.7L, 4wd SR5

  • Denny16Denny16 Member Posts: 4,774
    edited August 4
    I have aimed one of the front CoolCat vents towards the door and the stat works correctly.  I haven’t had a runaway issue like you did.
    July 2022 Edit:  I just completed a 4-day trip inland, where temps were in the high 90 degrees F, and had some short cycling one evening, aimed my USB fan at the door area where the thermostat is, and short cycling stopped.  So the extra fan helps.
     Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
  • dnordahl1dnordahl1 Member Posts: 5
    I think when I've had them aimed upward, then I get an issue with it cycling on and off constantly but I can give it another try.  I have some small USB powered fans I use in the summer when it's really hot.  I guess I could try pointing one directly at the thermostat as well.

     I did just find a possible alternative to the dometic thermostat which has bluetooth and wi-fi: Micro-Air ASY-351-X01

    I'll have to research more to verify compatibility. 

    2019 Nucamp Tab 400, 2007 Toyota Tundra 4.7L, 4wd SR5

  • ChrisKChrisK Member Posts: 238
    edited August 4
    dnordahl1 said:
     I did just find a possible alternative to the dometic thermostat which has bluetooth and wi-fi: Micro-Air ASY-351-X01

    I'll have to research more to verify compatibility. 

    Keep us posted on it. 
  • Dutch061Dutch061 Member Posts: 726
    edited August 5
    The Micro-Air ASY-351-X01will replace the Dometic CoolCat thermostat, but from what I have read there doesn't appear to be any kind of remote temperature sensor available. So outside of getting a pretty display and remote control, I don't see how it will help the OP's concerns with temperature control. It will only make is simpler to adjust since you can do so remotely. 

    Pretty sure that if my desire was high enough, I could get remove the thermistor from the board and make it a "remote sensor".  Even with that, I am not sure where the optimum placement would be, but do agree that away from the door would be a bonus.

    We are in a very warm area right now, and the thermal load is tremendous to say the least without any shade. A/C runs 100% of the time and struggles to get the temperature to the mid 80's inside during the day. That is an entirely different issue that is related to R values of the insulation.

    However, short of spending $100K, I don't see anything else that I would replace our 400 with. For those of you with a lot of extra money looking for something to buy, look at the Xplore X22.

    Brad
    2020 400 BDL aka "Boonie"
    2021 F-250 Tremor with PSD aka "Big Blue"
    Concord, NC 
  • jimcennamejimcenname Member Posts: 242
    edited August 6
    @Dutch061 did you install the Micro-Air ASY-351-X01? I'd like a remote for the thermostat, that is also easier to read.

    I run a USB fan in my 400 to keep the air moving around. I believe it helps moderate the temperature on hot sunny days.
    2019 [email protected]
    TV: 2017 Nissan Frontier SV 4X4
    Southern California
    Full-timer since 2019
  • ChrisKChrisK Member Posts: 238
    edited August 6
    Do you have the part number for the stock Dometic thermostat? I'm trying to solve a problem with my daughter's 400 and want to try replacing the thermostat. Also, if I may ask, her manual is in Denver with her and I'm in Phoenix. What model CoolCat is installed in the newer (2021) model 400.
  • Dutch061Dutch061 Member Posts: 726
    @jimcenname, I have not installed the new thermostat. I did search the model number and was easily able to confirm that the "351" is for the Dometic Thermostat used on TAB 400's, or at least the ones that I have seen.

    Here is the website that I verified this at https://www.rvupgradestore.com/Micro-Air-ASY-351-X01-EasyTouch-RV-351-p/asy-351-x01.htm

    My issue isn't moving the air, but rather the thermal load from not having any shade. This is further compounded by not having reflectex to put between the windows and the shade. However, the load from the roof itself is very high. 

    Brad
    2020 400 BDL aka "Boonie"
    2021 F-250 Tremor with PSD aka "Big Blue"
    Concord, NC 
  • Denny16Denny16 Member Posts: 4,774
    edited August 6
    @Dutch061 said, “ This is further compounded by not having reflectex to put between the windows and the shade…”
    Brad, this is a bad idea.  You need to put the reflectex on the outside of the window to reflect direct sun away from the window, and to reduce heat load inside the trailer.  Putting the reflextex inside the window, will reflect heat back into the window, causing it 
    to warp.  I just returned from a one week long trip, and the last two days saw 
    temps greater the 100F.  I put the reflectex on the outside of the star grazer window, and was able to keep the trailer cooled to 70-75 degrees F with the CoolCat and a small circulation fan running.
     Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
  • Dutch061Dutch061 Member Posts: 726
    @Denny16,

    Thanks for your feedback! We are 1800 miles from home, and I was going to look into this further before my placement after we got home. I have most of a roll there and don't want to buy additional. 

    My wife may decide that we are going to be hobos, if she does there is an Xplore X22 in my future. Really, really like the 400 but if we are going to live in it 100%, we need more space. 6 months will be fine for the 400, but I don't think I can do "full time" in it.

    Brad
    2020 400 BDL aka "Boonie"
    2021 F-250 Tremor with PSD aka "Big Blue"
    Concord, NC 
  • Denny16Denny16 Member Posts: 4,774
    Brad, the Xplore X22 is a very rugged looking trailer for taking off road and into the Aussie Outback.  If you plan to be mostly driving on paved highways and some improved back roads, this may be overkill.  You might also consider an Airstream 22 foot trailer or if you can find a used one, the nüCamp Avia, is very nice, with a high end build with Alde and CoolCat AC systems you are used to.

    Stay Safe and happy trails my friend..
    Cheers
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
  • jimcennamejimcenname Member Posts: 242
    @Denny16
    I used to cover the exterior of the front and back windows of my 400 and it helped tremendously with the inside temp. Covering/uncovering the windows every move became a hassle so I applied film to the OUTSIDE of all of my windows. Tint on all but the stargazer, which I covered with white light-blocking film. It works almost as well. @Sharon_is_SAM also applied tint to the outside of at least the front window. Been using the film for about two years. I can provide details and caveats if anyone is interested. 

    Originally used covers to keep heat outside:


    Applied non-adhesive contact cling film to outside (there are caveats):


    White film applied to outside of stargazer:

    2019 [email protected]
    TV: 2017 Nissan Frontier SV 4X4
    Southern California
    Full-timer since 2019
  • Denny16Denny16 Member Posts: 4,774
    The white film on the Stargazer window looks nice.  But we like looking out our big rear window, especially when camping on the coast, which is where we camp most of the time.  The window tint material is a good idea, which one did you use?  
    Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 8,669
    Just like indoor solar shades, I think the white, light blocking film reduces UV and heat, but allows you to still see out.  Although, IIRC, dark films allow for more visability.  Did I get that right @jimcenname?
    Sharon / 2017 [email protected] CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
  • jimcennamejimcenname Member Posts: 242
    @Sharon_is_SAM I think the dark film still permits plenty of light. It does a great job providing privacy until it gets dark at night. I appreciate the UV protection but my motivation is reducing heat. BTW, I don't have solar panels. I hear those panels really heat up the roof during sunny days. Also, @Sharon_is_SAM I installed the 


    2019 [email protected]
    TV: 2017 Nissan Frontier SV 4X4
    Southern California
    Full-timer since 2019
  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 8,669
    @jimcenname - I meant fabric solar shades used inside homes:). Can you see out of the white film?
    Sharon / 2017 [email protected] CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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