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  1. #1
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    Dometic RM1350 not cooling, tried just about everything

    Last summer the RM1350 in our 2019 260RD stopped cooling on LP while we were boondocking. Would cool on AC just fine but that has mostly stopped. Ran through a litany of diagnostics and checking different parts. Fans come on, AC heating elements work, LP pressure is tested and within spec, igniter works, thermocouple works, no errors on the display or when running the test mode from the upper board, all fuses checked, reset button on the thermocoupler thingie at the bottom of the flue has been checked, gone over everything with a multimeter, cleaned the flue, new LP burner, swapped lower boards for the heck of it, burped the cooling unit, no major changes. After burping the cooling unit, it cooled again on AC. But since all we really do is boondock, LP operation is more important so I switched it to LP and lost cooling in both modes. I admittedly did not burp it as most people I've seen online suggest, I just flipped it upside down, rocked it back and forth a couple times before flipping it back over and put it back in. I definitely heard the chemicals sloshing around, and there are zero signs of any chemical leaks from the cooling unit. I have noticed that the back wall of the freezer and the cooling fins are occasionally 15-20* over ambient on AC and LP so I believe it is heating the cooling unit as it should. The fans still kick on as well.

    At this point, the only thing I can figure is the chemicals in the cooling unit have crystalized somewhere and are preventing everything from flowing as it should. I'm leaning towards the burping "trick" again, but leave it upside down overnight to give the chemicals a chance to do their thing. I'd really rather not throw a new cooling unit at it if I can avoid it, especially since the one in there has worked on occasion.

    Anything anyone can think of that I'm missing?
    2019 Reflection 150 260RD - 2018 Ford F350
    Rest of the fleet: 95 Grand Cherokee with a lot of stuff, 15 JKU Rubicon with less stuff, 98 5.9 Grand Cherokee with a little stuff

  2. #2
    Site Team Second Chance's Avatar
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    I originally posted this a couple of years back after problems with our Norcold 1210. A very good tech taught be about the absorption refrigerator "reboot." Perhaps there's something in here of use:

    Our absorption fridge quit cooling last winter (had been in one site without moving for a couple of months). I called our trusted RV tech for advice... I posted the following after that experience:

    RV techs call it a "refrigerator reboot."

    When your absorption fridge quits cooling (cooling unit less than two years old) and an experienced RV technician tells you to do a "fridge reboot," listen to him/her. Late last week and over the weekend our Norcold 1210 fridge started not maintaining proper temperatures. I tracked it with a fridge/freezer thermometer and my infrared thermometer and got an ever-tightening knot in my gut. First thing Monday morning I contacted our favorite technician here in Las Cruces, NM, Richard's RV Service, fearing the worst. He asked the following questions:
    Is it the same on AC and propane? Answer: Yes.
    Did the problem come on suddenly - like flipping a switch? Answer: No.
    Did you smell ammonia? Answer: No.
    Do you see any yellow residue around the boiler, coils, or any of the other tubing on the cooling unit? Answer: No.
    Do you hear the cooling fans in the back cycling on and off? Answer: I haven't noticed them like I usually do - but the weather has been cooler.

    Richard's instructions: Turn the fridge off for at least five hours and let everything get down to ambient temperature in the back. Using a rubber mallet, periodically tap on all the pipes, tubes, and other refrigerant conduits I can reach, both while it's cooling down and after it's completely cooled. This process took until about 2:00 Monday afternoon. I then turned the fridge back on and continued to do the "rubber mallet frappage" periodically while the fridge was warming up/cooling down. I turned the fridge back on mid-afternoon and by the time we went to bed Monday evening, both the fridge and the freezer were getting back down in normal ranges and the infrared readings on the fridge fins and the back walls of the freezer compartments were very good.

    I kept a log and updated Richard a couple of times on Tuesday and he dropped by yesterday (Wednesday) to check. His diagnosis... an air bubble or chemical membrane in the refrigerant system. He said, "Congratulations!" and pronounced the fridge healthy. We both think the issue occurred because our RV hasn't been moved since we pulled onto this site on 10 November and the jostling an absorption refrigerator gets bouncing down the road helps keep the refrigerant stirred up and moving.

    Rob
    U.S. Army Retired
    Widowed and very happily remarried
    2012 F350 DRW CC LB Lariat PS 6.7
    2020 Solitude 310GK-R, MORryde IS, disc brakes,
    Sailun LRG tires, solar, DP windows, W/D
    (Previously in a Reflection 337RLS)
    Full time since 08/2015

  3. #3
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    Good info. Mine gets plenty of jostling (8.5 miles of dirt roads after 75+ miles of curvy dirt roads to get to our boondock spot), but at this point I don't think the cooling unit has actually failed, it just needs a reboot as you put it. I'll the tapping technique to my burping procedure and hope for the best!
    2019 Reflection 150 260RD - 2018 Ford F350
    Rest of the fleet: 95 Grand Cherokee with a lot of stuff, 15 JKU Rubicon with less stuff, 98 5.9 Grand Cherokee with a little stuff

  4. #4
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    So yesterday I pulled the new lower board out and put the old back in so I can return the board. Did nothing other than swap boards, and the fridge is at 34* this morning.
    2019 Reflection 150 260RD - 2018 Ford F350
    Rest of the fleet: 95 Grand Cherokee with a lot of stuff, 15 JKU Rubicon with less stuff, 98 5.9 Grand Cherokee with a little stuff

  5. #5
    Site Team Second Chance's Avatar
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    Quote Originally Posted by BigDaveZJ View Post
    So yesterday I pulled the new lower board out and put the old back in so I can return the board. Did nothing other than swap boards, and the fridge is at 34* this morning.
    Perhaps a cleaner/better connection than previously?

    Rob
    U.S. Army Retired
    Widowed and very happily remarried
    2012 F350 DRW CC LB Lariat PS 6.7
    2020 Solitude 310GK-R, MORryde IS, disc brakes,
    Sailun LRG tires, solar, DP windows, W/D
    (Previously in a Reflection 337RLS)
    Full time since 08/2015

  6. #6
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    At this point I think I'm going to use this thread as a journal of sorts to track what's been going on.

    Holding temp on AC. Today we had some blips in power from Xcel, and somehow a GFCI tripped on the shop where the camper is plugged in to. It switched to LP around 1:15 based on when my Nest camera went offline. At 5:15 the freezer was at 28* and the fridge at 56* with an ambient around 60*. Got it back on AC now, so we'll see where it's at tomorrow I guess.
    2019 Reflection 150 260RD - 2018 Ford F350
    Rest of the fleet: 95 Grand Cherokee with a lot of stuff, 15 JKU Rubicon with less stuff, 98 5.9 Grand Cherokee with a little stuff

  7. #7
    Site Team Second Chance's Avatar
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    Quote Originally Posted by BigDaveZJ View Post
    At this point I think I'm going to use this thread as a journal of sorts to track what's been going on.

    Holding temp on AC. Today we had some blips in power from Xcel, and somehow a GFCI tripped on the shop where the camper is plugged in to. It switched to LP around 1:15 based on when my Nest camera went offline. At 5:15 the freezer was at 28* and the fridge at 56* with an ambient around 60*. Got it back on AC now, so we'll see where it's at tomorrow I guess.
    Absorption fridges usually perform better on LP than on AC, so this still doesn't sound right (assuming that it still had good 12VDC power for the control board and gas valve).

    Rob
    U.S. Army Retired
    Widowed and very happily remarried
    2012 F350 DRW CC LB Lariat PS 6.7
    2020 Solitude 310GK-R, MORryde IS, disc brakes,
    Sailun LRG tires, solar, DP windows, W/D
    (Previously in a Reflection 337RLS)
    Full time since 08/2015

  8. #8
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    Yup, 12V is good, and LP pressure has been tested within spec. I'm stumped. In the service manual there is mention of the flue becoming detached from the cooling unit in rare instances with "rough riding coaches." We've checked this as well, and it appears to be intact.
    2019 Reflection 150 260RD - 2018 Ford F350
    Rest of the fleet: 95 Grand Cherokee with a lot of stuff, 15 JKU Rubicon with less stuff, 98 5.9 Grand Cherokee with a little stuff

  9. #9
    Setting Up Camp
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    I started having the same issue yesterday with my Norcold (now Norwarm) in 2021 260RD. We can't get the fridge to cool down. Outdoor temp is 70 degrees.

    We move every 4 or 5 days. Yesterday morning as we hit the road to our next location, I noticed temp in the fridge rising slowly. I have a SensorPush remote thermometer in it and it alerted me to the rise in temp. We have a set of lithium batteries (and solar) so we can keep the fridge running while driving. We checked and the fridge was running on AC from the batteries. The temp continued to rise slowly all day.

    We got to our next location on 50 amp, still not cooling. Cut over to LP, not cooling. Turned off for 5 minutes, back on, nada. I noticed some water in the bottom and side of the interior fridge which made me check the drip tray (probably splashed out while driving some windy back roads). It had a lot of water in it (and oddly, an ice cube but not one made from the freezer ice tray, but similar in size). I checked the outdoor panel and saw no water in the catch tray. I unplugged the white tube and lots of water came flowing out. I did find a piece of something/trash inside in the condensation drip tray that may have been plugging the outflow. Checked this morning and the condensation tray is empty, so that part is fixed, I hope. And humidity has dropped from 90% to 50%.

    It has been working great on a temp setting of 4 until now. We tried increasing it to 7 then to 9, no colder.

    Read in the manual that if the temperature sensor should fail, it will cut over to a backup operation system to cool it. We unplug the sensor, but that didn't help.

    Checked this morning and it is hovering at 48 degrees since midnight (lots of cold beer in the fridge might be helping). Freezers seem ok, frozen bananas are soft but everything else is frozen.

    I'm going to run through the suggested steps of turning off the fridge as @secondchance suggested, if we can get some ice to put in the fridge to keep it cold for the 5 hours.

    Any other ideas?

    Karen
    2020 GMC Sierra 2500HD Denali
    2021 Reflection 260RD Fifth wheel
    First time owner of RV

  10. #10
    Setting Up Camp
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    We called our dealership in MD and they suggested that something was clogged/frozen/not-moving in the pipes, and, as Rob @Second Chance posted, to do the rubber mallet tapping on the black horizontal cylinder thingy inside the lower panel (I forget what he called it - recovery tank?). He didn't say to do the 5 hour wait period (it had already been off for an hour though), just tap the tank and the pipes going in and out of it. We did that but it didn't fix it - the pipes got very hot so that piece was working, but the fans weren't coming on.

    He thought maybe the thermal sensor disk that turns the fans on and off wasn't working. He had us remove the wires connecting to the sensor (attached to the right side of the fins behind the upper panel) and connect them using a 10 or 15 amp fuse. We had a 10 amp handy, so used that. The fans turned on and the fridge and freezer started cooling, slowly. The fans are running continuously now and the fridge and freezer are holding good temps (it took over 24 hours for it to get into reasonable temps). The fridge is staying within the 32-38 degree range. The freezer seems to hold between 5 and 9 degrees - not getting down to 0 to -10, but ok.

    Hoping it will work for the remaining 8 days of our trip, then we'll get it into the shop to be looked at.
    2020 GMC Sierra 2500HD Denali
    2021 Reflection 260RD Fifth wheel
    First time owner of RV

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