I remember some sort of discussion around this but kinna find it.
We're camping in the coastal range atween Portland and the ocean, at around 1,000' and 102deg. The freezer is doing fine, but the main fridge is barely keeping cool.
Do I remember something about fitting an auxiliary fan, and does anyone have actionable diy plans ?
Oh, and there was a cougar and bear sighting here back on 6/5. Bear walked right through camp they say.
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I bought two 12 vdc computer fans.
Mounted one in the fridge section to promote circulation.
Mounted the other in the condenser section to promote circulation in the outside area.
They seem to help, especially the inside the fridge fan for cool down when first starting the fridge.
Wired both to the 12 vdc power supply to the fridge.
As a temp, quick fix, a small 120V fan (like a little desk fan) pointed at the lower (intake) vent of the fridge will help a lot by circulating air through the condenser fins outside. Even if the air going in is 102F, increased flow through there will help. Otherwise just the basics, don't open the fridge often, turn it to the coldest settings, run it on propane, and make sure the internal fins are not frosted up. An inside battery powered fan may help the internal frosting issue and we do use a little Valterra fan for that.
Hot enough for ya?
Oh, and bears are ok (usually), but watch out for the cougar. Them are dangerous.
Our fridge/freezer unit has a built-in fan that automatically turns on when it's warm back there behind the unit, but when the sun is shining on the back side of the camper the fan runs for a long time and the fridge doesn't stay as cold. So my wife had the idea of putting a sun shade over that portion of the back side of the camper where the fridge/freezer unit is. She bought a sun shade online that is about 3'x6' and I just mounted some anchors along the top edge of the camper that we can hook the top of the shade into using some caribeeners (put the short side of the shade along the top and hang the longer side up and down). Then will just tilt out the bottom of the shade about a foot or two and anchor it with some light rope and tent stakes. We haven't used it yet but it should help provide some shade on the side of the camper where the fridge is. Hopefully it will work well and help keep the temps in the fridge nice and cold! Will post a pic of it once we go camping in one month.
Quote from: Merlin on June 25, 2017, 12:48:56 PM
As a temp, quick fix, a small 120V fan (like a little desk fan) pointed at the lower (intake) vent of the fridge will help a lot by circulating air through the condenser fins outside. Even if the air going in is 102F, increased flow through there will help. Otherwise just the basics, don't open the fridge often, turn it to the coldest settings, run it on propane, and make sure the internal fins are not frosted up. An inside battery powered fan may help the internal frosting issue and we do use a little Valterra fan for that.
Hot enough for ya?
Oh, and bears are ok (usually), but watch out for the cougar. Them are dangerous.
We had it on 5, running off AC. Are you saying propane >> AC for cooling power ?
When you say the intake vent, you mean on the outside of the trailer ? 'cause there's no intake inside.
Also, I think the reefer on the 14dbs is the same as your 16, just mounted on the back wall instead of side wall.
The freezer did just fine. Everything was still frozen including a bag of ice cubes. This is a freezer compartment inside the reefer, not a separate door.
No frost on the fins.
By the way....we got one of these at Home Depot earlier in the week, for like $75.
https://www.amazon.com/Arctic-Cove-MBF018-18-Volt-Misting/dp/B00LFUQ0MG/ref=sr_1_4?ie=UTF8&qid=1498426936&sr=8-4&keywords=artic+cove+misting+fan
One of the big One+ batteries lasted over 6 hours, and having a misting fan to sit in was awesome for us and the dogs. Worked GREAT, and since we already carry 2 Ryobi One+ LED lanterns and use a Ryobi One+ driver to raise/lower the stab jacks we already have a charger with us in case.
I wonder if I had pointed it towards the rear intake if the reefer would have done better....
Our fridge cools down quicker on propane than on AC when we are getting it cool to start a trip. I translated that into propane >>>>> AC for cooling. I think (but don't know) the resistance heating element for the AC may not be as hot as the propane flame?
Our fridge is mounted on the back, and yes I did mean the outside intake area for the condenser fins, the lower of the 2 fridge vent areas.
A misting fan would cool things down back there, but all the water may not be good for the controls/wires.
I like gbpack's idea for a awning over the fridge area. Clever mod for when it's in full sun. Too bad my fridge doesn't have the auto fan Gregg mentioned.
I want to do a fan at some point. In the meantime, I put those rectangle ice packs in the freezer at night. In the morning I put them on the top shelf of the fridge. It seems to help and it's a quick solution.
Quote from: thedusty on June 27, 2017, 03:26:15 PM
I want to do a fan at some point. In the meantime, I put those rectangle ice packs in the freezer at night. In the morning I put them on the top shelf of the fridge. It seems to help and it's a quick solution.
I don't think the problem was inside the fridge, but outside. It just was too hot for the fridge to move that heat anywhere.
It sucks to think I've gotta have a cooler taking up space and feed it ice because the fridge can't keep up.
An auxiliary fan on the outside is looking more and more the way to go.
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i just spent 4 days in st george and experienced the same thing. with the 110 degree outside temps, the fridge was useless. the freezer was great..even
kept ice cream sammiches frozen. the fridge was allowed to cool completely over 3 days and i even packed it with ice jusgs when i put the food in. within 2 days all of the ice had melted and the fridge was warm.
for those running adv fan...where did you draw the power from inside the fridge?
also, isnt there a heating element meant to reduce condensation? can it be removed/disonnected?
I have heard you can fish the wire down thru the drain line in the back of the fridge.
You would then pick up power from the feed for the fridge.
Dusty - since you bought your 21BHS after ours, your fridge/freezer probably has the auto fan as well. Do you ever hear a faint buzzing or humming noise coming behind the unit (while you're inside the trailer)? Ours runs whenever it gets to a certain temp back there. On a hot day (or if the sun is shining on the back side of the trailer), the fan runs for quite a while until the temp cools down.
Before my LL I had a Aliner popup. The fan came on at 110 degrees and would keep you up at night with the noise. I added two 5 inch computer fans that were almost silent. The frid dropped 5 degrees when I turned the old one off and started the new ones. I tried this while camping at Inks Lake State Park in TX during the summer. I am thinking about adding one of the computer fans to my 16 TBS.
One of the advantages of the computer fans in the Aliner was the two of them only used 1/3 to 1/2 of the power of the old one. They also moved 4 times as much air.
Quote from: thudd3r on June 29, 2017, 10:24:26 PM
i just spent 4 days in st george and experienced the same thing. with the 110 degree outside temps, the fridge was useless. the freezer was great..even
kept ice cream sammiches frozen. the fridge was allowed to cool completely over 3 days and i even packed it with ice jusgs when i put the food in. within 2 days all of the ice had melted and the fridge was warm.
for those running adv fan...where did you draw the power from inside the fridge?
also, isnt there a heating element meant to reduce condensation? can it be removed/disonnected?
The heating element is a frame heater used in the 2 door Dometic fridges. The wire can (should be) removed to reduce power use and heat input to the fridge. Run a search using the term "frame heater" and you'll find a number of posts on it, including good info and photos from @tinkeringtechie and @charliem.
Quote from: Diversteve on July 01, 2017, 09:32:57 AM
I have heard you can fish the wire down thru the drain line in the back of the fridge.
You would then pick up power from the feed for the fridge.
Not sure why this would be necessary? If you want a fan inside the fridge for some reason, use a battery powered unit like the blue Valterra fridge fan.
What's needed, however, is a fan(s) OUTSIDE the fridge blowing air over the normally passively cooled (by convection) condenser fins and coolant lines that are between the intake and outflow fridge vents on the back (or side) of the trailer. There is 12VDC already available there and can be tapped into fairly easily to add a switched fan or thermostatically controlled fan. On a very hot day there often is simply not enough air moving over those fins and lines to remove enough heat to keep the inside of the fridge cool. My camper does not have a factory installed fan, but it sounds like I should look into installing a thermostatically controlled fan back there.
Here is one possibility posted in another thread by Chappy123
https://www.etrailer.com/RV-Kitchen/Valterra/A10-2618VP.html?feed=npn&gclid=CLiNg8vV6tQCFcWLswodKqUKvg
IDK why it was elsewhere but I meant to put it here. Thanks for the redirect Merlin.
Here is something else to look at. I checked the insulation on the sides of my fridge and found 2 gaps about the size of my fist. Tomorrow morning when it is cool, I plan to take both doors off and plug the gaps.
Conversation on the Facebook page regarding baffles between the back of the refrigerator hardware and the wall of the trailer itself. Cliffnotes version: There should only be an inch of space between the condenser fins and the wall of the trailer, if there's more there should be a baffle to reduce the space to about an inch. This causes air to move over the radiator fins and improves cooling.
Mitch
Thanks Mitch. I'll check it out.
Quote from: Merlin on July 02, 2017, 05:10:12 PM
Here is one possibility posted in another thread by Chappy123
https://www.etrailer.com/RV-Kitchen/Valterra/A10-2618VP.html?feed=npn&gclid=CLiNg8vV6tQCFcWLswodKqUKvg
Can you just hook that up to the existing fan?
Quote from: pjcd on July 06, 2017, 05:45:31 PM
Quote from: Merlin on July 02, 2017, 05:10:12 PM
Here is one possibility posted in another thread by Chappy123
https://www.etrailer.com/RV-Kitchen/Valterra/A10-2618VP.html?feed=npn&gclid=CLiNg8vV6tQCFcWLswodKqUKvg
Can you just hook that up to the existing fan?
Hmm...you could hook it up to the same power source, but I'm not sure about hooking it up to an existing fan (especially a thermostatically controlled fan). And, of course, that's not an option for those of us who are clueless; oops, I mean fanless.
Someone on Facebook posted this photo of what he found under the cover of his refrigerator panel:
(https://farm5.staticflickr.com/4217/35596278162_ab9cd746bd.jpg)
Unbelievable. But certainly something to check!
Strangely, it's like that on purpose and it's what the Dometic installation manual says should be done. Go figure, an inch between the back of the fridge and trailer wall is all that there should be.
Mitch
Weird.
I see something with fins and I assume freely flowing air to them is a good thing for heat transfer.
Unless I'm missing something.
Quote from: FastEddieB on July 06, 2017, 11:48:10 PM
Weird.
I see something with fins and I assume freely flowing air to them is a good thing for heat transfer.
Unless I'm missing something.
Maybe it wants a confined air column open at top and bottom to get natural convection going. Think about old home construction with a window above the door to let heat out which pulls cool air in from a lower window.
Just a guess.
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That's what the manual says. The narrow column forces air to flow over the radiator fins thus improving refrigerator performance. The material you see in that picture is is part of the baffle, it's not part of the fridge.
I'm going to look at mine between rain showers.
I'll report back what I find.
Funny, I had the covers off to install screens prior - mud daubers had clogged my propane jet. I certainly did not notice such a "baffle" at the time. Not to say it wasn't there.
I had the same exact experience Eddie and when I saw the picture I said to myself, "Geez, I don't remember seeing those" I went and looked and I don't have them. My fridge is really close to my back wall though so I don't need one.
I don't think we have one of those either, as I have been in the back portion of the fridge a number of times to clean out debris. Unless it's up higher than the area down below that we have access to. I'll take another look, only this time I'll look up higher. Not a problem if it's there (or not). Just am curious.
I'm hoping to resurrect this old thread rather than starting a new one... Had problems with my fridge holding temperature in the AC electric mode this weekend. When the fridge was on propane everything was great, 35 deg on the display. Set the trailer with my trusty level and switched to electric. Three hours later and I reached in to make dinner. Everything didn't feel all that cold. Temp was at 57deg. I switched back to propane and the temp started to drop. I tried electric again and it started to creep up. I came home and down loaded the trouble shooting guide. Being an HVAC-R engineer, I decided to dig in. I have a 2015 21RBS The Fridge is a Dometic RM3762LBFX. Two doors. I Ohmed out the electric heating element and checked all the fuses and voltages. All Good... There is one little computer tower fan located between the upper and lower exterior vent. It is cycling on temperature as it should (loud and annoying). I decided to pull the panels ad set up my blue blower squirrel cage blower and crank up the airflow over the outside coils. Outdoor temps were in the high 70's low 80's. Final conclusion as of tonight is the same as most have stated, the unit runs great on propane and only will function on electric when outdoor temps are below 70. I plan to swap out the little fan with two high velocity QUIET fans. There are mounting holes already there, but there is only one fan. I also plan to make a shroud similar to the one pictured in this post and see if it helps. It seems like the units that vent through the roof don't have these issues as much. FWIW the freezer worked fine on AC but the fridge just wouldn't keep up. I will also inspect the gasket on the door and report back. The only good news is that these units don't use much propane. My gut tells me that I will be running it on propane 90% of the time. Either way that annoying fan has to change! So far I am not very impressed with my dometic appliances. My old camper had a Norcold that ran like a champ in either mode. Any inputs or experience with this is greatly appreciated. Thanks everyone.
Quote from: Capt J-rod on September 17, 2017, 08:44:22 PM
I'm hoping to resurrect this old thread rather than starting a new one... Had problems with my fridge holding temperature in the AC electric mode this weekend. When the fridge was on propane everything was great, 35 deg on the display. Set the trailer with my trusty level and switched to electric. Three hours later and I reached in to make dinner. Everything didn't feel all that cold. Temp was at 57deg. I switched back to propane and the temp started to drop. I tried electric again and it started to creep up. I came home and down loaded the trouble shooting guide. Being an HVAC-R engineer, I decided to dig in. I have a 2015 21RBS The Fridge is a Dometic RM3762LBFX. Two doors. I Ohmed out the electric heating element and checked all the fuses and voltages. All Good... There is one little computer tower fan located between the upper and lower exterior vent. It is cycling on temperature as it should (loud and annoying). I decided to pull the panels ad set up my blue blower squirrel cage blower and crank up the airflow over the outside coils. Outdoor temps were in the high 70's low 80's. Final conclusion as of tonight is the same as most have stated, the unit runs great on propane and only will function on electric when outdoor temps are below 70. I plan to swap out the little fan with two high velocity QUIET fans. There are mounting holes already there, but there is only one fan. I also plan to make a shroud similar to the one pictured in this post and see if it helps. It seems like the units that vent through the roof don't have these issues as much. FWIW the freezer worked fine on AC but the fridge just wouldn't keep up. I will also inspect the gasket on the door and report back. The only good news is that these units don't use much propane. My gut tells me that I will be running it on propane 90% of the time. Either way that annoying fan has to change! So far I am not very impressed with my dometic appliances. My old camper had a Norcold that ran like a champ in either mode. Any inputs or experience with this is greatly appreciated. Thanks everyone.
Have you disconnected the door frame heater? Those 2 door models apparently have an energy-sapping frame heater to dry out condensation/frost and it might help to disconnect that wire. There's a photo of it on this forum. As others have noted, on AC the fridge takes forever plus a day to cool prior to a trip. On propane it's a few hours. I think the heating element is undersized for what it has to do. In these Dometic refrigerators, are there 2 heating elements, one for AC and one for DC? If not, and everything is run through the DC element, that might explain the poor performance. I'll go check the parts diagrams for mine and see.
Ok, After some deep internet research LOL, I have decided that I need to insulate the airspace above the refrigerator. Next I will build an air scoop that forces the air from the top of the fins to the top of the exterior vent. I plan to replace the fan with two quiet fans, and bend another piece of metal to force air over the coils. I suspect that the temperature control switch is not coming on soon enough. Most of the info I have gathered is from large RV's that have a fridge in the slide, forcing the mfg to use the side mounted vents. Apparently the roof vented models are much better at cooling. I will post later to say whether or not this helps. I also suspect that the door gaskets are not sealing up perfectly. This seems to be very common with dometic side vented refrigerators.
RE Merlin, Yes I disconnected the door heater. I also cleaned all the grounds as they had some mild corrosion. Needless to say I'm not impressed with these units. I just made another post, but I suspect the thermal switch for the cooling fan is coming on at too high of a temperature. This model is either 120V AC or propane. I already Ohmed out the electrical element @42 ohms. The manual wanted 44 +or - 10% so I am good there. I do think you are right that the electrical element is too small for the size of the fridge. That explains why the freezer stays cold but the fridge gets warm. The freezer pulls too many btus out and there is nothing left for the fridge. The propane has a lot more Btu's for the cooling system. I think if I can refine the airflow to the back of the unit it will help it a lot. There are mounting holes for a second fan, that should help some. I also might make a bypass switch to these fans for hot days when I'm plugged in to just let them run full time. I can understand the reason for LL picking this unit, one less hole in the roof. I just think it is sad to have to heavily modify a $1200 refrigerator to make it cool food. The fridge cycled between electric and propane since Thursday and continued to fail on electric this afternoon. If and when I fix it I will post the solution. That's what makes this site great!
https://bryantrv.com/docs2/docs/Service%20Manual,%20RM3762%20&%20RM3962.pdf
Page 24 does a half assed decent job of explaining absorption cooling for us geeks. It would have been nice had they actually put the letter that they reference in the description on the diagram though!
My model is not in this Pdf, but they seem pretty worried about the airflow... Our fridges are not installed like this!
http://bryantrv.com/docs2/docs/dometicventing.pdf
I'm adding my update to help the thread and others... I spoke to tech support at dometic. I will be fabricating a louver to help manage airflow. I will also add a second fan to increase the air over the condenser. Finally I ordered a new thermostat for the cooling fans. The range to the two door thermostat is on at 150degrees, off at 120 deg. The part for the single door fridge is on at 90 off at 120. this will bring the fans on sooner before the heat builds up. Any airspaces above or beside the unit greatly reduces the performance. Finally I was advised to inspect the weld on the heat exchanger for the electrical element to make sure that good heat transfer is happening. Once I get this done I will report to help close out my issues. This is probably long winded, but hopefully it will help someone in the future. The part number for the lower thermostat is #3313470.095.
The biggest downside for the second fan and stat is that it will hurt our boon dockers who are off grid.
Quote from: Capt J-rod on September 20, 2017, 06:53:50 PM
I'm adding my update to help the thread and others... I spoke to tech support at dometic. I will be fabricating a louver to help manage airflow. I will also add a second fan to increase the air over the condenser. Finally I ordered a new thermostat for the cooling fans. The range to the two door thermostat is on at 150degrees, off at 120 deg. The part for the single door fridge is on at 90 off at 120. this will bring the fans on sooner before the heat builds up. Any airspaces above or beside the unit greatly reduces the performance. Finally I was advised to inspect the weld on the heat exchanger for the electrical element to make sure that good heat transfer is happening. Once I get this done I will report to help close out my issues. This is probably long winded, but hopefully it will help someone in the future. The part number for the lower thermostat is #3313470.095.
The biggest downside for the second fan and stat is that it will hurt our boon dockers who are off grid.
Thanks for the continuing info. My fridge has no fan and needs a couple. I bought the fans and with your thermostat number reference I'll be all fixed up. I'm putting in an on/off switch too, so when I need to conserve power I can power off.
Here's a pic of the sun shade we devised to keep the sun off of the refrigerator section of our trailer. Works really well and helps keep the fridge much cooler when that side of the camper gets a lot of sun. We just bought a 3' x 6' sunshade and I installed some anchors to the top edge of the trailer. We then used a couple of small caribeaners to connect the shade to the anchors and then just used rope and stakes to tie down the bottom part of the shade. Our fridge is one of those that has the automatic fan built in, but this sun shade really helps to supplement that by keeping the fridge portion of the backside of our trailer cooler, which helps keep the temperature in the fridge lower. Even with outside temps in the 90's and full sun on that side of the trailer, the fridge temp stays in the high 30's and the fan doesn't have to work as hard (or long). Very easy and inexpensive mod.
It appears that your fridge vents through the roof. I think that the shade would restrict the airflow on the top side vent. I am rather disappointed by this whole issue. It wasn't the best design for a refrigerator, but it wasn't the best install and they didn't install it per mfg specs. I respect the idea of one less roof penetration, but not at the cost of a non functioning refrigerator. UGHHHH!
Quote from: Capt J-rod on September 24, 2017, 10:06:05 PM
It appears that your fridge vents through the roof. I think that the shade would restrict the airflow on the top side vent. I am rather disappointed by this whole issue. It wasn't the best design for a refrigerator, but it wasn't the best install and they didn't install it per mfg specs. I respect the idea of one less roof penetration, but not at the cost of a non functioning refrigerator. UGHHHH!
The top of the shade doesn't impair the vent or impede the airflow. It doesn't get up that high. So far this mod had been working well with the fridge remaining cooler and the fan running less.
OK, re-resurrecting this thread. I can start a new one if you prefer but it seems this one has the most/best troubleshooting info and makes it a good spot to continue the discussion. I have read and re-read many threads about the 3 way fridge performance and have now installed 2 fans below the exterior fins. They are working as expected when the temp is above 84 degrees although I might have them wired to always on because they run even if the fridge is off. I can work on that later but first.....MY FRIDGE IS STILL TOO HOT!
What steps to take next? This morning the outside temp is 80 degrees, fridge is on LP set at the coldest temp setting and has been running for a couple of days with outside temps between 70 and low 90s. The back of the fridge is shaded all day in our driveway. Interior fridge temp this morning is 50 degrees. The freezer is fine.
During the fan install I confirmed that the baffle appears to be installed correctly per the manual. I had to cut it and remove it to install the fans but then reinstalled the piece I cut out (it ain't pretty in there!). I can feel the warm air coming out the top vent.
Question: for our model RM2554 in the operating instructions no where does it reference the interior thermistor that is attached to the cooling fin. Does it's position on the fin help control temp settings? In reviewing the manual just now I see it is mentioned in the troubleshooting for if the fridge is too cold then this thermistor may not be attached and centered. Maybe I'll take it off today and see if the temps drop.
So right now my next option is interior fans but it seems I should be getting better cooling now and I'm thinking either something is wrong with the unit or I'm just completely missing something here. Help!
Ah, the absorption fridge saga! I have done all the mods suggested herein (except the lovely sunshade idea) and still find performance only marginally improved in hot weather. To control an inside circ fan, I installed a temp sensor in the fridge 'ceiling' just in front of the freezer door. It reads in the 70's, even low 80's (with the door closed) during hot days, on propane to boot. (It is accurate since I tested with my body temp.) I remain confused (alas, an ongoing state of mind) since the food was cool but not cold. Maybe as the air cools in the fridge, lingering hot air gets trapped up there?? But why doesn't the circ fan mix it up? The best I got at night (ambient temp 50) was 55.
My next step is to place a thermometer in the main fridge compartment. Depending on what I find, I'll re-route the sensor there. If the seeming lack of hot air forced out of the rear top vent is any indication, the placement of my large computer fans is amiss. https://aluminumcamperforum.com/index.php?topic=866.0 I'd really like to get some robust air flow; anybody try a small squirrel cage fan? Also, I note some recommend air flow over the condenser lines (those pipes that zig-zag upwards)-meaning fan is installed in the lower vent vs over the cooling fins. Comments?
I sometimes wonder how much air flow is enough during warm weather. Anybody try pushing air up the rear of the fridge with a 'real' ie. household fan? I wonder how long the fridge will last before I get the chance to install a marine compressor unit...LSW willing?! GK
In my experience, an interior fan helps with evenness of temps inside more than it helps with overall cooling inside. Try the thermistor placement change, but spend most of your time outside. Getting good airflow on the external fins will help the most, as will adding any extra insulation you can fit in on the sides and top of the fridge. If the unit has changed in its ability to cool it's certainly possible there's a leak.
And, maybe a good question...are you sure the burner is clean and you have a good flame? The refrigerator at my cabin would get rust in the "chimney" that would fall down on the burner and almost snuff it out. I had to take the inspection cover off the burner and blow the junk out of the supply pipe and off the burner every year. It wouldn't surprise me to find the rough life of an RV fridge leading to the same problem.
OK so both this morning and yesterday morning fridge temps were in the low 40s and by late in the day they were mid 50s. Ambient temps between 70 and 95. Making progress. This morning I turned off the fridge and tonight I will pull the shroud off and clean the flue and burner. It doesn't seem very dirty in there compared to other (working) units I've seen but I would be remiss if I didn't try it. It's only 18 months old but it does sit outside year round.
We head out to camp Wednesday for 4 days and hoping we can keep our food cold enough to avoid food poisoning! I think I will pre-cook some things so I don't have to worry as much about them. Or maybe I'll just put meats in the freezer since it is cold. I detest the thought of another weekend using a cooler when I spent thousands to be able to glamp vs camp!
What is the freezer temp? I think all of the cooling coils are in the freezer, at least on a single door model and maybe you aren't getting enough heat transfer from the fridge to the freezer.
The fridge in my 2016 21BHS actually runs OK on electric but doesn't cool good on propane.
EDIT: Upon further inspection I found a piece of insulation blocking part of the exhaust vent for the propane flame, once this blockage was cleared the fridge works perfect.
I found this absorption fridge website that appears to have some veracity. https://www.arprv.com/rv-fridge-fan.php (That said, they tilt towards some paranoia regarding fire potential..)
One comment resonated with me. The point of external fans is not to remove hot air, but to increase/create air flow. Therefore, they recommend a fan at the lower and upper vent and sell a 120 mm ball bearing centrifugal/squirrel cage variety that pushes 25 cfm. The fan runs at relatively a relatively low 1800 rpm and draws only 0.3 amps. I like the fan, but cost is steep @$30USD.
They say the fans are custom spec'd. I can vouch for that. After a long search, I got close (at 1/3 the price), but still only found 120mm or so centrifugal fans that rotate much faster and take twice the amps or more.
If I buy the cheaper fans, add a (resistance) controller to reduce rpms, then according to Ohms Law, I would reduce amps, right? Or am I perplexed (as usual)...or just too darn cheap? GK
Circulating hot air isn't going to help. You have to get rid of the heat.
Since heat energy can't be created or destroyed, the system is moving heat from inside the refrigerator to outside. The outside coils must be able to get rid of the heat by heating the air in that location. If it is not able to get rid of the heat, because the outside coils are already in hot air, cooling performance suffers. You're fighting the laws of physics.
All refrigeration systems have a maximum temperature differential between the two sides of the system. As I recall, the electronic coolers can provide a 30 degree change in temperature. Absorption systems are more efficient, but may not be able to get more than 40 to 45 degrees of temperature differential. (I couldn't find any specs.) Regardless of the system, the hotter the "outside" temperature is, where the outside coils are, the warmer the refrigerator interior will be.
This situation is typically qhidden from us because our home refrigerators are in air conditioned space. We're used to consistent refrigerator temperature because it is in a room with constant temperature. In the camper, this is not the case. If you put your home refrigerator outside in the heat, you would see the same problem. The more you can cool the back side of the RV fridge, the cooler it will be inside the fridge.
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So essentially we have to refrigerate the cooling coils to improve the refrigerator performance. In the world of IT this closely resembles nested IF statements, makes perfect sense.
I'm thinking maybe I'll put a tent up over the entire RV and then refrigerate that tent ;)
LOL
As a computer programmer, I get it and agree!
There's only so much that a refrigeration system can do. Whatever chemical process is used, it can only drop the temperature a certain amount. As the ambient temperature goes up, the ability to obtain 35 degrees on the cold side is lost.
I suspect the biggest problem is the installation. Consumers demand larger capacity in a limited space, so insulation suffers. It gets cool enough at night to get the inside cold, but the back and sides of the refrigerator are subjected to a lot of heat in during the day.
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For what it's worth, we have a small portable Dometic absorption refrigerator that we use in our 6.0 and now 8.1. Since it is not installed in the camper, the "outside" coils are inside the (somewhat cooler) air conditioned camper / tent. I've been quite pleased with the performance. Unless it's 95+ outside, it often freezes diet soft drinks and water bottles.
The ammonia cycle absorption system is capable of doing a very good job.
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Right around zero. Frozen!
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Quote from: Steve Sanders on July 02, 2018, 01:11:43 PM
Circulating hot air isn't going to help. You have to get rid of the heat.
Since heat energy can't be created or destroyed, the system is moving heat from inside the refrigerator to outside. The outside coils must be able to get rid of the heat by heating the air in that location. If it is not able to get rid of the heat, because the outside coils are already in hot air, cooling performance suffers. You're fighting the laws of physics.
All refrigeration systems have a maximum temperature differential between the two sides of the system. As I recall, the electronic coolers can provide a 30 degree change in temperature. Absorption systems are more efficient, but may not be able to get more than 40 to 45 degrees of temperature differential. (I couldn't find any specs.) Regardless of the system, the hotter the "outside" temperature is, where the outside coils are, the warmer the refrigerator interior will be.
This situation is typically qhidden from us because our home refrigerators are in air conditioned space. We're used to consistent refrigerator temperature because it is in a room with constant temperature. In the camper, this is not the case. If you put your home refrigerator outside in the heat, you would see the same problem. The more you can cool the back side of the RV fridge, the cooler it will be inside the fridge.
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I've heard the same in regards to the a/c. That it can only lower the temp 15 degrees or so below the outside temps. All makes sense to me. I may set up a fan outside the lower vent to push more air this weekend however with temps predicted to be in the low 90s I'm not very hopeful. I think our site is in full shade though so we'll see.
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Wait, are we all IT here? I'm a software developer. Totally get the nested ifs.
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Quote from: mojospeople on July 02, 2018, 06:37:58 PM
Wait, are we all IT here? I'm a software developer. Totally get the nested ifs.
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SAS database programmer.
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They should do better than 15 degrees, but that's the idea. They don't make "cold", they relocate the heat. If it can't heat the air outside, then it can't move the heat to make it cooler inside. If the outside coil is in hot air, 15 degrees could happen and explain this thread. With cooler outside air, 40 to 50 degrees or more is possible.
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Quote from: mojospeople on July 02, 2018, 06:37:58 PM
Wait, are we all IT here? I'm a software developer. Totally get the nested ifs.
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I am a software developer too!
Quote from: Steve Sanders on July 02, 2018, 08:00:18 PM
They should do better than 15 degrees, but that's the idea. They don't make "cold", they relocate the heat. If it can't heat the air outside, then it can't move the heat to make it cooler inside. If the outside coil is in hot air, 15 degrees could happen and explain this thread. With cooler outside air, 40 to 50 degrees or more is possible.
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The 15 degree cooling was in regard to the air conditioning problem my dad was having in high heat and humidity. Sorry to confuse.
Tonight armed with a screwdriver, wire brush and a can of compressed air I opened up the unit. Everything looked shiny and new. Did I mention we almost always run on electric so the gas hasn't been run much at all? No soot and minimal dirt and dust. So I guess I've done all I can do. It's turned on and cooling in prep for the holiday outing. I need to hope for cooler camping temperatures and pay close attention to the fridge temps in hot weather.
Yea! Current outdoor temp, 74. Current fridge temp, 36. Today is going to be low 90's with a heat index of low 100's. Will see what the fridge temp is tonight.
Quote from: mojospeople on July 03, 2018, 09:35:45 AM
Yea! Current outdoor temp, 74. Current fridge temp, 36. Today is going to be low 90's with a heat index of low 100's. Will see what the fridge temp is tonight.
Keep the door closed as much as possible.
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As data points, 21BHS with Dometic fridge...
In 94º to 96º daytime temps near Knoxville, TN, fridge temps can creep up to the high 40's during the day, but the freezer seems to stay below freezing. Overnight, temps drop down to mid-to-low 30's to start the day. This is all parked in partial shade, and running on 120v.
Quote from: FastEddieB on July 04, 2018, 10:39:28 PM
As data points, 21BHS with Dometic fridge...
In 94º to 96º daytime temps near Knoxville, TN, fridge temps can creep up to the high 40's during the day, but the freezer seems to stay below freezing. Overnight, temps drop down to mid-to-low 30's to start the day. This is all parked in partial shade, and running on 120v.
That about matches the performance of the Dometic in my 2013 21BHS.
@FastEddieB, do you have an exhaust fan behind the fridge, or is yours stock.
(sorry if you've already answered this in a previous post.)
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I just installed this Valterra fridge coil fan in the outside compartment of my Dometic 2 door fridge. I was reading about the record heat in Canada and since we are headed there shortly, I figured I'd give our fridge every benefit of the doubt. I can't vouch for longevity yet, but I can say the installation was extremely easy. Valterra provides a bunch of mounting options and the 12V power is right there in the compartment. I just screwed one of the mounting plates to the wall and hung the fan directly above the lower coils. I tested it and it comes on and goes off thermostatically right on cue. My only complaint was that it did not come with the recommended in-line fuse and really should have for the price. I added the fuse because 12V can go bad in a hurry (fire) if the wire insulation or a connection fails.
https://www.amazon.com/Valterra-A10-2618VP-FridgeCool-Volt-Exhaust/dp/B002N5YDG2/ref=sr_1_1?ie=UTF8&qid=1531100069&sr=8-1&keywords=valterra+fridge+vent+fan
Has anyone added simple computer fans to the back airspace? I have several that are 12 volt and would work fine I think but I'd need some sort of controller. Also exactly where can we tap into 12 volt power in the back of the single door 5 cf model? RM 2554 I think, I'm not near the camper or the manuals at the moment and if I wait to ask these questions until I am I'll forget about the whole thing because that's what happens when you age and your brain turns to mush.
I've run 2 12V computer fans in my Rpod fridge for 4 years. They are hot glued to the lower louver door and suck air in, blows it through and it exhausts out the top louver door..
At the top is a simple thermostat used for attic fans. Works well.
Here is the T'stat>
https://smile.amazon.com/gp/product/B002TYK4A6/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 (https://smile.amazon.com/gp/product/B002TYK4A6/ref=oh_aui_search_detailpage?ie=UTF8&psc=1)
Sounds like what I'm thinking. That tstat you linked is 120 volt though, I'd need 12 volt since I mostly boondock. Thanks for the response!
It is a switch. It doesn't care what you put through it AC or DC. Been working fine for 4 years on 12V ;)
I added a 12vdc computer fan to ours.
I just used a toggle switch that i turn on as needed.
Very simple install and it works great.
Quote from: Diversteve on July 09, 2018, 09:27:33 PM
I added a 12vdc computer fan to ours.
I just used a toggle switch that i turn on as needed.
Very simple install and it works great.
Same thing I did, simple yet functional!
The Valterra outside fridge coil fan I reported on in post 61 above has been working great. We have followed a heat wave west and have twice hit 100F in the shade this past week. It's been at least 80sF every day. The fridge is running about 40F inside, on either gas or 120V electric, and set on 4 (not the max of 5). The outside fan is coming on and going off with the thermostat and I have a lot more confidence in something designed for the extremely rugged life of an outdoor fridge fan. Very high and low temps, extreme humidity, dust, small insects, and constant bouncing when underway seem like way too much long term for a computer fan that is designed for a sedate couch-potato like life. The only problem we've had is that when opened frequently (lots of cold drinks on hot days), these absorption fridges don't recover temps as fast as compressor fridges. We are about to leave the heat wave and head way north into Alberta, so pretty soon we'll be enjoying hot drinks!
Define long term :P
Here are the $8 fans I used in my Rpod> https://www.amazon.com/gp/product/B0026ZPFDE/ref=oh_aui_search_detailpage?ie=UTF8&th=1 (https://www.amazon.com/gp/product/B0026ZPFDE/ref=oh_aui_search_detailpage?ie=UTF8&th=1)
They've been in use for, I'd guess, 180 days at least over the last 4 years- 3 30 day long trips many 3-7 day trips and covered 25,000+ miles. ;)
Probably be putting the same in the 16TBS when I get a chance. Although I may not need them since the 18 16TBS has the fridge vented out the roof.
IME having both intake and exhaust in a wall hurts performance quite a bit- I think Dometic even alludes to this somewhere in their installation literature.
Computer cooling fans are much more robust than you would expect. It is true that most are in a clean environment, but many operate in very hot and dirty places. (Think about Garden Center sales terminals or computers in mines.) Those little fans are designed to run 24/7/365 for years, anywhere a computer might be used. They are designed for the worst conditions and are cheap because millions of them are produced.
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(https://uploads.tapatalk-cdn.com/20210508/b056b87875ac2b2000167595d307138d.jpg)
I bought this vent fan to cool my fridge in my 2016 TBS. I know how to attach to the vent but not how to wire it. Any simple diagrams or other suggestions? Thanks!!
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Quote from: dlb53151 on May 08, 2021, 01:39:11 PM
(https://uploads.tapatalk-cdn.com/20210508/b056b87875ac2b2000167595d307138d.jpg)
I bought this vent fan to cool my fridge in my 2016 TBS. I know how to attach to the vent but not how to wire it. Any simple diagrams or other suggestions? Thanks!!
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Looks like quite the unit! I wired my single Valterra fan into the DC terminals that are available in the rear fridge compartment of my 16TBS. My fan is controlled by an internal thermostat, so I'm not sure I can help you with the speed controller wiring of yours. Do you know where those 12DC terminals are in the compartment, or would you like a photo?
Merlin - yes please send a pic - thanks!
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Sorry, I've once again given up in frustration with not being able to post photos on the forum. If you want a photo, use the messages features and send me your email. I'll attach the photo I just took to a return email.
In lieu of a photo, I can tell you the DC terminal in the fridge compartment is a white screw terminal block with 4 connections. in/out DC positive (orange) and in/out DC negative (white). It's easily seen and accessed in the bottom of the lower compartment. This is for a 3-way fridge that has the DC option for running the absorption cooling system. Huge wires because the 12VDC amps are very high for the fridge heater. I simply added my fan wires (+and -) to the terminal block for fan power and put a 2A fuse/holder in the + wire.
Hi Merlin - My email address is dlb53151@yahoo.com. For everyone's benefit here the fan I am referring to. (https://uploads.tapatalk-cdn.com/20210510/1b1684b8e1a51a1f0aaa3a0d2ede2d83.jpg)
Here's the view of back of fridge from top vent.(https://uploads.tapatalk-cdn.com/20210510/b1cc3bab0ce22161ea08ed1693e908dd.jpg)
Here's view from bottom vent.
(https://uploads.tapatalk-cdn.com/20210510/cacf38402ff10aebc18d96352b6913e6.jpg)
Here's how I mounted the one fan (after splitting apart) on the top vent (blowing out).
(https://uploads.tapatalk-cdn.com/20210510/502f609057c2f8ae0e2ba7b01f5641ce.jpg) I mounted the other fan on the bottom vent in the same manner, with zip ties (blowing in, however).
Thanks for your input Merlin. This is a must-do mod for anyone traveling in hot climates.
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At the bottom of the middle photo you can see the orange/white wire DC terminal block I referred to earlier. I'm working on how to resize photos so I can post. I'm such a Luddite when it comes to digital photos......I miss my darkroom. :-\
How does Tapatalk work?
Update on fan installation.
I added this temperature controller.
HiLetgo 2pcs W1209 12V DC Digital Temperature Controller Board Micro Digital Thermostat -50-110°C Electronic Temperature Temp Control Module Switch with 10A One-channel Relay and Waterproof
I wired the controller in the circuit after the toggle switch.
Now i don't need to remember to turn it off when the temperature is cool enough for the natural circulation to keep the area cool.
Diversteve - can you please share pics of your controller installation? Haven't installed my controller yet.
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I'm currently modding my fridge. Spent $80 and the mod consists of:
4x Coolerguys 80mm x 25mm IP67 rated fans
2x Coolerguys 80mm x 15mm standard fans
4x 3 PIN Y Splitters
2x 3 PIN to Bare Wires
The 80mm x 25mm fans fit pretty much perfect between the cover outlet and lines up with the position on my condenser fin. They are secured with zip ties at the bottom and a thin bead of caulk at the top. To increase forcing air out the vent and not having it deflect back into the fridge compartment I used foil tape. The tape also helps securing the top of the fans on top of the caulk.
The 80mm x 15mm fans I mounted alligator clips to them in order to clip them to the interior cooling fins to circulate air.
I plugged into the circuit board to 12V pin that was not being used labled (lamp/heater) and is only active when the fridge is turned on. This way the fans are on when the fridge is turned on. I do not boondock so IMO to reduce the stress on the fridge's cooling system it was not worth the money or stress on the fridge components to not keep these fans running all the time to help fridge temps and circulate air.
Wow, THAT should help a lot.
Quote from: Merlin on June 28, 2021, 07:55:06 PM
Wow, THAT should help a lot.
So far the outside compartment temp has been 15-20 degrees cooler, even with all the hot and humid temps through Michigan. That compartment drop has resulted in the fridge temp being a couple degrees cooler.
Inside fans are getting installed today and expecting that to drop the temp a good amount.
Agree with WOW. Great idea with the aluminum tape. GK
Sorry for the late reply.
When we bought our 21 RBS used last year the seller disclosed that they had replaced the circuit board for the Dometic refrigerator.
Last fall I was camped the military campground in Key West in September and October. The weather was unseasonably hot for the Key. The refrigerator was struggling to stay cold. We were using shore power with the frig on auto. Had a retired RV tech talk me through trouble shooting and we were able to determine it was the "thermomister" probe on the fins inside the frig. Overpaid for a replacement part from an RV supply company, turns out the same part is available on Amazon for a much lower price, and installed the replacement with some challenges or running the wires to the board.
Everything worked fine until we got back in the heat of the Keys this winter and the daytime temperatures started to climb and by sunrise had barely gotten back in to the upper thirties.
Fortunately for us our neighbor, who are full timers, is an RV tech. We had her come over and check our refrigerator out and she determined the fan to move air was no longer working. To replace that fan would require removing the frig to do so and it was agreed to just abandon it in place. With the use of a step ladder and small electric fan placed at the bottom of the frig with the access cover off to move air up the back over the fins. This worked well.
I then decided to remove the top vent cover since I could not see any daylight when looking up from the bottom access panel. Once the cover was unscrewed which was made difficult by someone at the factory thinking it was a good idea to fill the screw holes with lap sealant making the screw removal take four times as long as it should of. With the cover finally off I discovered that the fins were ¾ blocked at the top by fiberglass insulation. Appears that when the refrigerator was installed and slide in the insulation on the top sides pushed back and laid on top of the fins greatly reducing convective air flow (see enclosed picture).
With the use of a coat hanger fished through the wire mesh I was able to push and prod the fiberglass insulation off to the sides. Needless to say the refrigerator performance has greatly improved now. Stays in the 36-38 degree range now regardless how hot it gets here now. This is a black trailer with the frig in the sun from late morning until Sunset.
Also installed two new fans. One at the bottom and one at the top. Both have a thermomister probe for putting the fans in the auto mode. A manual mode option is also available.
Decided to put a squirrel cage type fan on the access panel to pull air in and up: https://www.amazon.com/dp/B0C6T1LLMX?psc=1&ref=ppx_yo2ov_dt_b_product_details
For the top vent a more standard type square fans: https://www.amazon.com/dp/B09NLFDLD1?ref=ppx_yo2ov_dt_b_product_details&th=1
So far very pleased with the results.
Forgot to add the RV Tech believes both the theromister and board issues with the frig was due to this blockage.
Good work. And good trouble-shooting. Classic install error at LL.