Rear exterior cooling fan on Dometic RM2554 fridge

[Outsider]

2020 Rockwood G19FD with Dometic RM2554 gas/electric fridge. (We've had it for 2 years.) Manual "coolness" setting for this model is 1-5 with 5 being max cool.



We camped for 5 days last week in 95 degree temps and the fridge had trouble keeping cool for the first 1.5 days then all of a sudden all was fine. I had pre-cooled for 24 hrs on 110VAC (as normal), the inside temp was 42 or 47 degrees (I forgot which) when we left home. Switched to gas cooling for the drive and temp was still about the same when we arrived at the shady camp site 6 hours later. Next day the temp inside got up to 52 and finally started coming back down that evening. Held a steady 37-39 for the next 3 days.


I discovered that this unit has a rear-side exterior cooling fan about halfway up between the upper and lower cooling vent. It appears to be factory installed. It is nearly impossible to see from any angle but it is there. I'm wondering if maybe that rear fan failed to work properly the first 2 days of this trip.


HERE'S MY QUESTION: Can anyone tell me for absolute sure how/when that fan should be running? I suspect it is turned on/off by an in line heat sensor somewhere back there. Can I "force" it ON by some means?



It is a week later now and we are leaving for another 4 day trip Monday morning. I'm pre-cooling again today (on 110VAC) and the temp is coming down nicely inside (as normal) with the coolness set to "4". Looking up through the lower rear cooling vent I can see that the fan is not turning.

[tomkatb]

Those fans were not from the fridge manufacturer.

The instructions say these fridges should not be installed in slides. Need the overhead exhaust.

So the rv guys install usually a pair of computer fans behind the upper vent. And a piece of plywood to help direct flow.

They are connected to a set of screws in the back of the fridge. Remove the lower vent and you can find the wires. Matches no other wires.

We do business with Amish rv. They suggest an additional squirrel cage fan for way more air flow. Helps the unit out. The Amish use these fridges. Around northern Indiana they make the units and service them.

They installed a switch so that in hot weather the fan is always on.

Otherwise the fans are on only when the unit is heating. Connected to the same contacts.

[bigmurph]

Fans are not from fridge manufacturer but are from trailer manufacturer probably. My 2016 Flagstaff has a roof vent (installed in a regular wall not a slide) but still has the fan. I bought it new so I know they installed it. Mine runs alt when hot outside. For instance, when at the beach a couple of weeks ago it would run each day from say 10am till after dark. My previous Salem didn't have this fan or it never worked because I never heard it. That fridge didn't stay as cold as my current one.
Just my .02

[NJKris]

I have the 2019 G19FD. There were no fans. The fridge struggles in high heat like that. I have installed a thermostatically controlled pair of vent fans inside the upper grate to pull the hot air out, and installed a circulation fan on the fins in the fridge, plus continue to use a little battery operated circulation fan on bottom of fridge. I have not had opportunity to test for improvement in very hot conditions yet (that trip is coming in a few weeks), but freezer temp gets down to -15°, fridge into 30's.



I've discovered the biggest problem keeping fridge cold is how it is loaded. When it's too full, and items are covering a lot of the wire shelf area, the fridge section struggles to stay in the 38-40° safe range, even with both interior circulation fans running. Right now it's half full, outdoor temps in 70's, and I had to turn it less cold (mine you have to slide the thermister down the fin in the fridge), as fridge temps were nearing 32°.

[Outsider]

OP here. Camping with no signal & no wifi. Will respond in 3-4 days. Fan is not your typical add-on. Could only have been installed with fridge OUT. More later.

[Outsider]

OP here: Back home. Thanks for your input.


Additional input for your thoughts. Last week when the fridge had trouble staying cold (for just the first 2 days) we had hookups so we ran on 110VAC the whole time (other than traveling to the site when we were on gas).


This trip we were in the NC mountains where the outside temps were never over 79 degrees and nights were about 58-60. We had no hookups so we were on gas the entire time. Fridge inside temps stayed about 38-40 with the coolness set to 2 or 3 on the front control panel. I checked the hidden fan on the back side of the fridge that is half way between the two cooling vents a time or two but never saw it running.


In relation to a previous input comment, there are no "slides" on this model GeoPro and the only way the fan could have been install is with the fridge out. I'm the 2nd owner and I REALLY doubt that the first owner pulled the fridge to install the fan. He just was not the type to do something like that and he only had it for about 6-9 months.


There is no switch anywhere in the camper to manually turn the fan ON/OFF so again, I'm guessing it has a thermal controller somewhere.


Any other thoughts? I believe if that fan would work it would help a LOT. I guess I may have to install 1 or 2 fans in the upper outside cooling vent hole area to pull heat off the fins but as mentioned before, it normally works very well.


Thanks for your input.

[NJKris]

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1


This is the one I installed in upper grate. It is thermostatically controlled in auto mode, or has a manual mode. I keep it in auto, to come on with temps are 80 or higher. I still had trouble staying cold in fridge, even with 2 circulation fans INSIDE fridge. Freezer was getting down to -15°, fridge still struggling to get below mid 40's. I'm convinced it is an internal air circulation issue. My last 4 nighter in relatively mild temps, the freezer was going down to -17°, fridge was almost freezing inside. Had to adjust fridge temp so things wouldn't freeze. The difference? Fridge was only half full, not going on safari full, which I think just blocks air flow.


***I was boondocking last trip, so on gas entire time.

[Outsider]

Thanks NJKris. I was hoping you would send me that info.


For the record, I also installed an air circulation fan inside my fridge right after I got it (1.5 yrs ago) and it runs manually all the time I'm using the fridge.

[Outsider]

OP here. (NOTE: All my pics got flipped so I hope everything is still understandable.) Dometic is closed today so thought I'd come back here with more info for everyone and a follow-up question.


As mentioned earlier, I felt pretty sure that this 2020 GeoPro G19FD came from the factory with a cooling fan mounted on the back of the fridge. (I'm the 2nd owner.) I went back to the original Dometic fridge install manual and found that there was a model RM2554 (One Fan) shipped in some units. (I plan to attach pics.) The bottom left corner of the schematics shows the 2 added items for the fan. F-Thermostat, Y-Fan. As pictured, the red (+12VDC) wire on the left side of the thermostat comes from J2 (labeled Lamp/Heater) on the control PCB, goes through the thermostat and then goes to the Fan.


I have been able to verify that there is +12 VDC at J2 when the fridge is turned ON and arrives at the left side of the thermostat. If I jump across the thermostat pins the fan does operate fine.


I let the fridge run for a couple of hours on 110 VAC and even added heat up into the lower outside cooling vent opening with a heat gun but could never get the thermostat to trip and turn the fan on by itself. (I even sealed off the upper cooling vent opening for an hour or so. I'll ask Dometic tomorrow but does anyone know at what temperature the thermostat should trip and turn the fan ON? Right now I'd say it is my problem.


Thanks for your help.

[pgandw]

Originally Posted by Outsider

OP here. As mentioned earlier, I felt pretty sure that this 2020 GeoPro G19FD came from the factory with a cooling fan mounted on the back of the fridge. (I'm the 2nd owner.) I went back to the original Dometic fridge install manual and found that there was a model RM2554 (One Fan) shipped in some units. (I plan to attach pics.) The bottom left corner of the schematics shows the 2 added items for the fan. F-Thermostat, Y-Fan. As pictured, the red (+12VDC) wire on the left side of the thermostat comes from J2 (labeled Lamp/Heater) on the control PCB, goes through the thermostat and then goes to the Fan.

I have been able to verify that there is +12 VDC at J2 when the fridge is turned ON and arrives at the left side of the thermostat. If I jump across the thermostat pins the fan does operate fine.

I let the fridge run for a couple of hours on 110 VAC and even added heat up into the lower outside cooling vent opening with a heat gun but could never get the thermostat to trip and turn the fan on by itself. (I even sealed off the upper cooling vent opening for an hour or so. I'll ask Dometic tomorrow but does anyone know at what temperature the thermostat should trip and turn the fan ON? Right now I'd say it is my problem.

I ran into the same issue with DM 2354 installed in my A-frame - the factory fan only came on when it was over 100 outside, too late to do any good. But getting at the fan to fix/replace would mean pulling the fridge. As it was I had to rerig the baffle so that it actually worked as intended.

So I ignored the fan, and put 2 12V (70ma draw, 1200 RPM, 120mm) computer case fans directly on the exhaust grill, with a manual switch on the inside of the camper. Unless it's winter camping I just run the fans full time while camping. I start the fridge off at max setting ("5"), then pull it back to "4" or sometimes "3" depending on internal temp. I monitor internal fridge temp with an $11 Walmart wireless battery-powered thermometer, and use a Camco fan inside the fridge to even out the temps internally.

Fred W
2019 Flagstaff T21TBHW A-frame
2022 Hyundai Palisade

[Outsider]

Yep, I strongly considered that option as well. And actually it probably would have been cheaper. But, the fridge had worked so well up until 5-6 weeks ago I decided to replace the little "switch in a can" that apparently has failed that turns the fan ON/OFF.


I won't tell the long story but from outside the camper while standing on a 2-step stool I was able to reach down inside the cavity and prove that the current fan is actually working and then was able to disconnect and pull out that little switch. (Glad I don't have Popeye fore-arms.)


I called Dometic, got the replacement part # and ordered one online from Boat & RV Accessories (through Walmart). They were the cheapest I could find at $80 + tax. It should be here Sept 11th.

[Bob K4TAX]

I"m always doing some custom engineering work on our TT.

I have two fans installed in the vent at the roof. One is a 12 VDC fan which is connected to the gas valve. Thus when the gas valve is open and the flame lit, the fan runs. When the gas valve closes, the fan does not run.

The second fan is a 120 VAC fan connected to the control board where the 120 volt heating element is attached. If we have shore power and the refrigerator calls for cooling, the 120 VAC fan runs. When no cooling is required, the 120 VAC fan does not run.

Of course, I could have designed and installed a more complex automated system. One that determines if one fan or two is needed, at what temperature to turn the fans ON or OFF regardless of the power source available, and at what temperature. But in my book, KISS was the better and more reliable option.

Bob

[chriscowles]

Originally Posted by Bob K4TAX

I"m always doing some custom engineering work on our TT.

I have two fans installed in the vent at the roof. One is a 12 VDC fan which is connected to the gas valve. Thus when the gas valve is open and the flame lit, the fan runs. When the gas valve closes, the fan does not run.

The second fan is a 120 VAC fan connected to the control board where the 120 volt heating element is attached. If we have shore power and the refrigerator calls for cooling, the 120 VAC fan runs. When no cooling is required, the 120 VAC fan does not run.

Of course, I could have designed and installed a more complex automated system. One that determines if one fan or two is needed, at what temperature to turn the fans ON or OFF regardless of the power source available, and at what temperature. But in my book, KISS was the better and more reliable option.

Bob

I like that approach

[NJKris]

Originally Posted by Outsider

Yep, I strongly considered that option as well. And actually it probably would have been cheaper. But, the fridge had worked so well up until 5-6 weeks ago I decided to replace the little "switch in a can" that apparently has failed that turns the fan ON/OFF.


I won't tell the long story but from outside the camper while standing on a 2-step stool I was able to reach down inside the cavity and prove that the current fan is actually working and then was able to disconnect and pull out that little switch. (Glad I don't have Popeye fore-arms.)


I called Dometic, got the replacement part # and ordered one online from Boat & RV Accessories (through Walmart). They were the cheapest I could find at $80 + tax. It should be here Sept 11th.

For 80 bucks you could have gotten the thermostatically controlled double fan set I sent you link to. Hope it works out for you. I still think biggest problems with these fridges are putting too much in them (even pre-chilled). Just doesn't get enough air circulation with stuff on shelves. Half full, it seems to be fine.

[chriscowles]

Originally Posted by NJKris

For 80 bucks you could have gotten the thermostatically controlled double fan set I sent you link to. Hope it works out for you. I still think biggest problems with these fridges are putting too much in them (even pre-chilled). Just doesn't get enough air circulation with stuff on shelves. Half full, it seems to be fine.

Ours is stuffed full. I've never had a problem keeping it cold. We do have a little battery-operated cube fan on a shelf but the batteries often go dead before we remember to check. (We use rechargeable D cells.)

[pgandw]

Originally Posted by NJKris

For 80 bucks you could have gotten the thermostatically controlled double fan set I sent you link to. Hope it works out for you. I still think biggest problems with these fridges are putting too much in them (even pre-chilled). Just doesn't get enough air circulation with stuff on shelves. Half full, it seems to be fine.

I am convinced that improved air circulation over the fins can increase the efficiency of these fridges - both the inside and outside fins.

On the inside, having the fridge partially full promotes air circulation and heat transfer between objects at different temps. Totally empty or stuffed full doesn't promote that air circulation.

Because I use nearly all the space in the small 3.1cu ft fridge, I use a small fan inside to circulate the air across the fins and through the fridge. Expensive for what it is, the $20 Camco fridge fan works very well on 2 D cells for about a month of continuous running. Stuff is pretty evenly cooled, temps don't rise as much after opening the door.

Unfortunately, Forest River often does a crappy job of fridge installation when compared to Dometic installation instructions. The sides and tops are not insulated as per instructions, the baffle is not installed correctly, and the propane burner exhaust was not directed to the exhaust grill. Dometic doesn't help matters with intake and exhaust grill designs that won't naturally pass air in a hurricane (I exaggerate a little), but do keep most rain from getting in.

I use the computer case fans because they draw minimal current (I have no solar), are cheap, are very quiet (unlike the Dometic fan), and they are easy to mount to the exhaust grill itself. But any method that forces air across the external cooling fins works. Proper baffling in accordance with Dometic instructions helps a lot in getting air cooling the fins instead of flowing through. And insulating the gaps around the sides and top of the fridge helps a little more.

just my experiences
Fred W
2019 Flagstaff T21TBHW A-frame
2022 Hyundai Palisade

[NJKris]

I added a hard wired inside fin fan from BeechLane, same company that made my exterior vent fans. It works great when fridge is not packed. Too much stuff on shelves and I'm lucky to keep fridge in 40's when it should be 38-40 F. I have a dual probe fridge monitor. The freezer will be -15° or colder, and fridge will only be in mid to upper 40s if too much stuff is on shelves. Stuff in plastic blocking shelves is the worst. Have to continually remind wife to be careful about that.


I brought my 40 year old dorm fridge from college out of basement to take on OBX trip to keep beverages in outside. It still works great! Kenmore, back when Kenmore was good (along with other brands before all the cost cutting measures).


Last year I was paying 8 bucks a bag for 20# of ice for the cooler for beverages every day, that got expensive quick. Those little ice machines usually only make tiny hollow ice cubes, no good for coolers. Think I'll bring the dorm fridge instead of cooler every long trip like this for now on.