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Old 06-12-2021, 11:30 PM   #1
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Default Refrig (Dometic) rookie question

I am having a small brain burb when it comes to my Dometic (Model RM2554). When on shore power, the fridge gets appropriately cold. However when I am traveling it no longer stays cold. Seeing the indicator lights illuminate, I know it is getting power. What is the proper 'switch setting' on the refrig. control panel? I am assuming: ON and AUTO, but am I looking for AC or DC on the number two button? PS, occasionally I will notice the CHECK light lit, but I understand that only applies when on propane (which I don't run when parked and certainly not when driving). Thanks in advance for any and all help.
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Old 06-13-2021, 12:47 AM   #2
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switched to "auto":

the unit should select AC if you are on shore power or running the genny

if AC is not available it may try gas

if your gas is off if may light the check light, or select DC

my results are not consistent, and I usually end up selecting the power source manually on the panel

even so on occasion the check light comes on and I assume it's not cooling, so I switch off then on

there are all kinds of strategies from replacing the fridge to adding fans,

I have added fans ( including 1 small fan internal to the fridge) and can count on 60ļ below ambient temps on gas.

my part time job is monitoring fridge operation and managing energy use in the van

to keep the fridge cold on 12 volt while driving I rotate freezer packs from freezer to fridge- and if we stop for any length of time switch on the gas


the manual is available online and I "tuned" up the gas by cleaning the flue and resetting the igniter gap- easy adjustments which make a difference


BTW on my van there is a fuse HIDDEN behind the black plastic control module...i wouldn't have known if I hadn;t been poking around making self more familiar with the fridge/nemesis


Mike
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Old 06-13-2021, 03:28 AM   #3
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I attached the Operating instructions from the RM2554 manual. A added a few notes to help.

When you disconnect from shore power for your travels, and you are not using gas, then you must manually press the DC mode selector button (2) until the DC light comes on. Because DC draws so much power, you do not want to operate in this mode for very long (30-60 minutes or less) without driving the vehicle. That is what this mode is mainly for: to hold the fridge temperature while traveling until you can hookup to shore power or to operate the fridge on gas. DC does hold my fridge temperature pretty good while traveling, but others have found the DC mode does not hold temperature very well, and the fridge temps go up. Mkguitar found he had to use freezer blocks in the fridge to keep it cold.

The Check light lit because when you disconnected from shore power the fridge switched to operate on gas. But since you had the gas turned off the gas temperature sensor did not detect a flame so it turned on the CHECK light. At this point there is no cooling and your temps will go up until you turn the fridge off then back on. You need to have the gas on, or hook to shore power, or manually switch to DC; if not then the CHECK light will again light up.

As mkguitar said, these fridges need particular attention. I highly suggest you get a wireless fridge temperature monitoring system so you know what your fridge temperatures are. These can be setup to warn you when your fridge temperatures go up to unsafe levels.
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Old 06-13-2021, 03:47 PM   #4
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Thought I would add this link to information on improving gas absorption fridge performance. I have done a few other things since then and will try to update when I get the time.

https://www.classbforum.com/forums/f...ance-8484.html
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Old 06-13-2021, 06:16 PM   #5
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I recently installed a new Dometic RM2554 refrigerator. I just found they have changed the manual somewhat, though the operation is still the same. Here is the operating instructions page from the new manual.

Dometic has now added a condenser fan on the back of the cooling unit.
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Old 06-17-2021, 07:44 PM   #6
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Default Replace your refrigerator with a 12 volt Danfoss Secop compressor

Quote:
Originally Posted by peteco View Post
I recently installed a new Dometic RM2554 refrigerator. I just found they have changed the manual somewhat, though the operation is still the same. Here is the operating instructions page from the new manual.

Dometic has now added a condenser fan on the back of the cooling unit.

Propane refrigerators are not being installed on many new RVs. They now have a very high efficiency 12 volt refrigerator....

My previous experiences with propane refrigerators found that they don't work consistently, have leveling and elevation issues...

You're going to be so much happier with the all electric refrigerator. There's many choices, Nova Kool and Isotherm......
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Old 06-18-2021, 11:35 PM   #7
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Ex-HVAC tech from many years ago, but the knowledge is still with me. I have the same model fridge and here is what I've done. Disconnected the 12V by putting in 2-way control board. (I'm sure there may be a different way to do it) 12V is useless and causes more harm than good. (When traveling turn the propane on at stops, or if it's really hot, run the generator while driving for 15 minutes or so, you get the same or better results) If for some reason you have it on 12V and forget, or the issue many have had, it doesn't switch over, you trash your battery. If you have it on gas, and you're sure the propane is on, it lights, goes out after some time on, most likely it's the igniter. (Replaced mine, because the check light would come on 3-4 times a day while living full time, and since replacing the igniter I've had no issues in the last 2-3 years.Many have the outside fans, IMO they're pretty useless. Others will disagree with me. I have a rechargeable fan on the top shelf pointed at the evap fins. I also have another that's charging via the 12V cig lighter. The model I have last about 6 hours. That doesn't mean you have to change it right away. When living full time I would simply change it in the morning. then sometime during the day and again before bedtime. My ice cream is frozen and drinks in the fridge cold. No fancy external temp or app on my iPhone. My two cents. BTW even in 100 degree weather.
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Old 06-18-2021, 11:44 PM   #8
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>I have a rechargeable fan on the top shelf pointed at the evap fins.<

Interesting solution. I imagine one of those little USB fans and a power bank type battery might be a quick solution to test out.
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Old 06-19-2021, 12:03 AM   #9
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Default Which model refrigerator are you referring to?

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Originally Posted by ChicagoTom View Post
Ex-HVAC tech from many years ago, but the knowledge is still with me. I have the same model fridge and here is what I've done. Disconnected the 12V by putting in 2-way control board. (I'm sure there may be a different way to do it) 12V is useless and causes more harm than good. (When traveling turn the propane on at stops, or if it's really hot, run the generator while driving for 15 minutes or so, you get the same or better results) If for some reason you have it on 12V and forget, or the issue many have had, it doesn't switch over, you trash your battery. If you have it on gas, and you're sure the propane is on, it lights, goes out after some time on, most likely it's the igniter. (Replaced mine, because the check light would come on 3-4 times a day while living full time, and since replacing the igniter I've had no issues in the last 2-3 years.Many have the outside fans, IMO they're pretty useless. Others will disagree with me. I have a rechargeable fan on the top shelf pointed at the evap fins. I also have another that's charging via the 12V cig lighter. The model I have last about 6 hours. That doesn't mean you have to change it right away. When living full time I would simply change it in the morning. then sometime during the day and again before bedtime. My ice cream is frozen and drinks in the fridge cold. No fancy external temp or app on my iPhone. My two cents. BTW even in 100 degree weather.
Hi Tom,

I imagine that you're talking about the 12 volt connection on a 3 way propane refrigerator, correct? Not a 12 volt/120 volt AC compressor refrigerator...?

'--Mark
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