Dometic RM 7401 cooling issues - need ideas I am at my wits end

Discussion in 'Heating / Cooling Systems' started by kevinpf, Sep 18, 2020.

  1. Anthony Hitchings

    Anthony Hitchings Well-Known Member Silver Supporting Member

    Messages:
    2,200
    Likes Received:
    1,211
    Joined:
    Mar 2, 2019
    Location:
    Oakland, California
    why not call Dometic and ask them about the burping idea ?? You have nothing to lose.

    Will you burp clockwise or counterclockwise?
    Will you burp by rolling or pitching?
     
  2. Anthony Hitchings

    Anthony Hitchings Well-Known Member Silver Supporting Member

    Messages:
    2,200
    Likes Received:
    1,211
    Joined:
    Mar 2, 2019
    Location:
    Oakland, California
    Instead of burping, a how about the old "shake-ah shake-ah shake-ah" as per the Chef John on Foodwishes.com
     
    Last edited: Sep 20, 2020
  3. Spridle

    Spridle Well-Known Member

    Messages:
    1,204
    Likes Received:
    396
    Joined:
    Jun 6, 2011
    My 2009 has fans on it controlled by the board. I thought they were all the same after 2007.
     
  4. Eric Young

    Eric Young New Member

    Messages:
    11
    Likes Received:
    13
    Joined:
    Sep 27, 2019
    When you are home your fridge is empty so it will not take much to get it to temperature. When you leave for the campsite you load up the fridge so it depends how you load it up. You need to make sure you don’t over load it and give it air for circulation around the food. These refrigerators work differently then house hold refrigerators. Also they work best if you prechill you food before putting in the fridge. When traveling I usually put mine on 12 volt when hooked to the TV and flip it to electric at the site. Hope this helps.
     
  5. Grandpa Don

    Grandpa Don Well-Known Member

    Messages:
    833
    Likes Received:
    571
    Joined:
    Sep 5, 2018
    But he says the temp is fine at home. It seems that Propane is the issue on site.
     
  6. Sjm9911

    Sjm9911 Well-Known Member Gold Supporting Member

    Messages:
    8,811
    Likes Received:
    6,214
    Joined:
    May 31, 2018
    Location:
    Nj
    I think hes saying to make sure it stays closed while traveling. If it opens, or isnt totally closed you loose all the cold air and are basicly starting from scratch to get the temp down when you arrive at the campsite.
     
  7. Kdague

    Kdague Member

    Messages:
    30
    Likes Received:
    22
    Joined:
    Sep 15, 2020
    Is that a 220volt fridge.
     
  8. Kdague

    Kdague Member

    Messages:
    30
    Likes Received:
    22
    Joined:
    Sep 15, 2020
    Did you take the vent grill off the side of the camper and make sure the condenser wasn’t dirty? May be on the top of the fridge. Also, when I looked that model up online it said it was a 230volt model, if that’s the case are you connecting to 220 volts at the camp ground
     
  9. Kdague

    Kdague Member

    Messages:
    30
    Likes Received:
    22
    Joined:
    Sep 15, 2020
    Did u make sure it doesn’t still have the winter grills on
     
  10. SgtRon

    SgtRon Member

    Messages:
    67
    Likes Received:
    52
    Joined:
    Jun 7, 2017
    Location:
    Florida
    The 3 way fridges have never lived up to minimum standards in my opinion. I finally got fed up enough to tear the damned thing out and replaced it with an apartment 110vac fridge (we never wilderness camp, so LP and 12vdc operation was never part of the equation anyway). Now we load up the fridge, the day before leaving, everything gets good and cold (35°-36°), then we head out. Fridge holds temp 4 or 5 hours, with door closed. When we hookup to shore power at the campground, it's all good. Fridge is good and cold in a very short time. (We have a cooler that has drinks, so we don't have to open the fridge during it's re-cooling down stage) we are also very pleased that we can keep ice cream and other frozen treats solid, we were never able to do that with our 3-way, on any mode of operation!
     
    AMC likes this.
  11. Nanette

    Nanette New Member

    Messages:
    1
    Likes Received:
    0
    Joined:
    Jul 22, 2017
    Are you making sure the camper is level at the campground? If it’s off it won’t cool properly.
     
  12. ajmaudio

    ajmaudio Member

    Messages:
    43
    Likes Received:
    2
    Joined:
    Jun 21, 2015
    IS there a significant elevation change between home and camp?
     
  13. Stereo56

    Stereo56 New Member

    Messages:
    13
    Likes Received:
    16
    Joined:
    Jul 16, 2020
    Given everything that you have checked and done, it seems to me there are only two possible variables.

    One is how the fridge is packed. You have to have enough free airspace for the cold to circulate. Even with the interior fan, if the food is really packed in there, the cold won't be able to circulate. There must be at least 1 inch of space between the food items and the back wall and some spaces between some of the items on each shelf.

    Secondly, it takes a long time for the fridge to recoup cold every time it's opened. There would definitely be a difference between leaving it alone in your driveway and using it at a campsite if you're in and out of the fridge a lot. To limit the amount of time we have the door open, we organize the fridge with items in individual bins so we can pull a whole bin out, get what we want, and then put the bin back in, rather than rummaging around in the fridge.

    Good luck!
     
  14. jjsdad

    jjsdad New Member

    Messages:
    5
    Likes Received:
    0
    Joined:
    Dec 12, 2018
    I have a 2007 Niagara. I don't recall the fridge model and make off the top of my head. I've heard lots of stories in general about any fridge that is any model travel trailer. So far I haven't had this issue. It sounds like you either may have one of those battery operated fridge fans on the inside to help circulate the inside air, and also have a fan on the outside to help cool down the fins on the back of the fridge. These are great ideas, and normally help. These are assumptions, so here are my questions to help understand your problem. The inside fan, battery operated or did you wire the fan in? If by chance to drilled and wired in inside fan, you may have caused the problem you having, by inadvertently drilling through something other then just the fridge case. The fans on the outside, are they blow air over fins or sucking air over fins? I haven't done this mod as of yet but plan to. Here are my thoughts on it. I have plan to add 1 computer fan to the top of the fins to blow air over and through fins, add 2nd fan down toward the bottom of the outside fridge housing, and having that fan blow out of the fridge housing (most likely on plastic removal grate), to have max air circulation. You may not have enough air circulation in the back housing causing fins to not cool properly. I only mention the above because you mentioned you did the fan mod and you have an issue on both electric and gas. I'm assuming you keep the back fridge compartment clean and free of any debris.

    A problem you may have, but would only relate to gas, is the exhaust chamber. I had a 5th wheel trailer that I had some type of bugs or rodent make a next in there while it was in storage. Wasn't fun trying to figure it out, as I know you can imagine. Once cleared, it ran better then ever. However that would explain the issue your having on electric, I believe, but not completely sure. However I do notice a difference in temperature when running on electric. Temp just doesn't seem to get as cold as it does with gas. I've ready this seems to be the issue with all travel trailer fridges no matter what the make is. Gas seems to be the best option.

    Next solution maybe to bleed and refill with freon. You may have a bubble or air in the lines cause an interruption in the fluid/gas exchange. Causing the fridge to kinda start all over once the air passes through. (Hope you know what I mean by this and understand how fridge cools with fire hahaha I had to Google it when I first started camping because I could wrap my head around how a fridge can cool by fire)

    I hope this helps you with some ideas to trouble shot. I would want to spend that kind of money on a new fridge. Also might want to call and talk to someone at ColemanPopUpParts.com I have my own problems right now with the roof not raising, and even though I still haven't figured it out completely, these guys are great to bounce ideas off. FYI if you have issues with the roof not wanting to raise, chances are its the Thrust Bearing. Hahaha hope this helps you man. Keep us posted on what the outcome is or was.
     
  15. CWiersma26

    CWiersma26 New Member

    Messages:
    8
    Likes Received:
    0
    Joined:
    Jul 2, 2019
    If you don't boondock and are comfortable running off of 120v you could very easily rip the fridge out (cap the gas line!) and put in a small dorm room size fridge (some even have small freezers); you can find them pretty cheap second hand. I was about to go this route but did the fan mod and that worked well. I also use an electric cooler as a second fridge and a high-quality cooler as a freezer packed with ice for all the meat.
     
  16. kevinpf

    kevinpf Member Platinum Supporting Member

    Messages:
    61
    Likes Received:
    21
    Joined:
    Jul 5, 2015
    Location:
    Southern California
    Thanks everyone for the thoughts and ideas.
    I truly appreciate the time and effort you have all taken to offer ideas and help.
    Let me try to respond to the questions and the actions already taken.
    1. From 2005 thru 2009 per Coleman/Fleetwood documents all Highlander models used the Dometic RM 7401-L refrigerator
    2. Yes I have both the external fans and the fans on the fins. The fans on the interior fins are tapped into the 12 v constant for the light, no extra holes
    3. The issues I am having pre-dated the fan installs. They were the reason for the fans
    4. I am VERY careful in how I pack the fridge to assure airflow and also have a blue circulation fan (battery operated) in the fridge to circulate the air.
    5. Altitude is not the issue, I live near the Pacific ocean and camp in Sequoia and Big Bear both 4-6000ft, as well as in San Diego at sea level and the fridge is inconsistent everywhere
    6. I have pre-cooled the unit 24 hours prior to a trip, put food directly out of my home fridge into the unit and traveled to the campsite trying both 12v and propane on the road, no difference, still have a 10 - 15 degree temp rise
    7. I had thought it might be the temp adjustment knob failing but that only comes into play with 120v or 12v.
    8. In order to evacuate the system and recharge with Ammonia the service folks are quoting $600 -$800 so not sure the extra $400 to $500 for a new unit may not be a better choice
    9. The idea of a bubble in the system is very valid and from what I have read it will require "burping" the unit which entails removing the unit from the trailer and upside down and back several times to work the air out of the system
    10. I have had someone else suggest I take the stack and flue off the unit and clean the inside as it evidently builds-up carbon and rust over time.
    I am wondering if it could be an intermittent issue with either the thermistor or control/regulator.

    Well this is fun....noto_Oo_O[{}=][{}=]
     
  17. kevinpf

    kevinpf Member Platinum Supporting Member

    Messages:
    61
    Likes Received:
    21
    Joined:
    Jul 5, 2015
    Location:
    Southern California
    Electric or propane the same thing occurs.
    Last October I was at a full hook-up site and the POS started at 39 degrees and proceeded to rise to 50 and would not go back below 48 degrees the entire trip. When I am at a hook-up site I have tried it both ways and there does not seem to be a difference
     
  18. kevinpf

    kevinpf Member Platinum Supporting Member

    Messages:
    61
    Likes Received:
    21
    Joined:
    Jul 5, 2015
    Location:
    Southern California
    Pulled the shelves completely and double checked the seal, don't see or feel a leak. I have a temp gun and it is not showing temp diff around the door.

    I am concerned it is the control board, especially because the issue is intermittent but predictable
     
  19. mtnbkr88

    mtnbkr88 New Member

    Messages:
    5
    Likes Received:
    7
    Joined:
    Jun 14, 2019
    Location:
    Big Bear City, CA
    On a typical three-way fridge, 12v DC is very inefficient and pretty much worthless. Gas is best. I cool my fridge with 110v the night before then put my chilled food and a few frozen water bottles in then switch to gas for my drive to the campsite. I put a fan in the back top vent. Make sure the back is free of bugs and debris and the flue is clear and level the trailer with a bubble level (Bubble Level Pro app on Android works good).
     
  20. Anthony Hitchings

    Anthony Hitchings Well-Known Member Silver Supporting Member

    Messages:
    2,200
    Likes Received:
    1,211
    Joined:
    Mar 2, 2019
    Location:
    Oakland, California
    aif the flue has not been literally eyeballed to be clear, then it needs to be. Wasp nests are solid and may to blow out. I rodded the net out of my chimney
     

Share This Page