High altitude problem???

[SteveJ]

Originally Posted by davdent

We have a 59g Travato with the larger 3 way absorption fridge. We have travelled extensively at high altitude both in way below freezing and most recently in the current heatwave conditions. The fridge has been faultless. I do suspect it is harder to start on gas in hot weather though.

We only use battery when driving or stopped for short periods. Never 110. We tend to stay in what we would call the scrub so use gas most of the time. We get 4 weeks out of a tank. We are very careful to level the van and use an iPhone app to make sure we are under 3 degrees. Preferably 2 degrees. The fridge is very cold and the freezer frozen solid.

I have read on this forum over many months opinions that would differ from this and I have to disagree absolutely. I would choose this type of fridge again for the ability to get it away from it all for an extended period. We have used an absorption fridge in a Jayco previously and again it worked perfectly.

We had a chat to a couple with a 59k in Yellowstone 3 days ago and they lamented on their 12/110 fridge that wasn’t keeping things cold and they had to use an ice container to keep things cold.

It would be accurate to say that my experience differs from what I have read on this site on this topic.

Yesterday it was in the mid nineties both in and out of the coach. Running on propane my fridge was at 31 degrees, at7000 feet of altitude, cooling fans running for the top coil.

RM2451 Dometic.

Not a fanboy of absorbtion fridges, necessarily. Had I known that the Onan was coming out later I would have went compressor fridge. But my RM2451 does what it's supposed to with no drama. I like that.

[Doneworking]

We are boondocking at 8000 elevation. Our Dometic is set at midway on the dial and it has been at 37 degrees interior with the freezer at -2 for almost a week. That’s on propane and we drove to our destination through hundred degree heat and it got up to 39. We have always had this same experience over 35 years of Bs and Cs. Never give it a thought otherwise.

[DWorrell3]

I have the NOVA R4500AC/DC. I like "Boosters" technical response. I can give you subjective info. I've left the RoadTrek unoccupied for 24 hours with the frig running and the batteries never came off "fully charged". I've seen You Tube tests run that suggest, with a 150w solar installation, you could run maybe 4 -1/2 days, well over any capacity of RoadTrek black/ gray water tanks. Additional, running the generator for 2 hours will likely recharge your batteries. Sure is nice to have real ice cream, not ice cream soup. Never will go back to expansion type frig. Dave W

[SteveJ]

Originally Posted by DWorrell3

I have the NOVA R4500AC/DC. I like "Boosters" technical response. I can give you subjective info. I've left the RoadTrek unoccupied for 24 hours with the frig running and the batteries never came off "fully charged". I've seen You Tube tests run that suggest, with a 150w solar installation, you could run maybe 4 -1/2 days, well over any capacity of RoadTrek black/ gray water tanks. Additional, running the generator for 2 hours will likely recharge your batteries. Sure is nice to have real ice cream, not ice cream soup. Never will go back to expansion type frig. Dave W

I'm pretty sure that running the genny for two hours will not recharge the battery (ies) unless they are lithiums and running an under hood extra alternator.

The holding tanks on my Roadtrek are good for a week traveling as a couple, two weeks traveling solo. This includes showers/sponge baths, coffee, sweet tea, cooking, washing dishes, toilet flushing and maybe hand washing a few garments until I hit a laundromat.

Apparently you had an absorbtion fridge that had installation and/or mechanical issues. My fridge has been stellar even with temps over 100 degrees, keeping the fridge temps in the safe range. And yes, I have a thermometer inside the fridge.

[booster]

Originally Posted by SteveJ

I'm pretty sure that running the genny for two hours will not recharge the battery (ies) unless they are lithiums and running an under hood extra alternator.

The holding tanks on my Roadtrek are good for a week traveling as a couple, two weeks traveling solo. This includes showers/sponge baths, coffee, sweet tea, cooking, washing dishes, toilet flushing and maybe hand washing a few garments until I hit a laundromat.

Apparently you had an absorbtion fridge that had installation and/or mechanical issues. My fridge has been stellar even with temps over 100 degrees, keeping the fridge temps in the safe range. And yes, I have a thermometer inside the fridge.

How much charge you get from the generator is very variable, and also dependent on the definition of recharging the batteries. This is confused on the forum all the time. Most posters are referring to replacing the energy they used when the say "recharge the batteries", and they are not saying that they will get the batteries 100% full. This is why I used a reduced usable capacity in the calculations of run time in a previous post.


The normal type size shore charger that the generator will be running is about 45 amps rated and will net about 40 amps continuous until the batteries are about 70% full, at which time the amps start to taper. That would give 80ah of recovery in two hours, which is two days of frig use. If that was two hours of driving with a stock alternator setup you would get somewhere in the 50-80amps continuous so 100-160ah recovery if you were below 70% SOC. Basically, an hour of driving would give two days of recovered power.


You certainly don't need lithiums and an engine generator to run a compressor frig. You don't even need an huge battery bank or solar, depending on your use patterns. The way many of class b users travel, which is moving a lot like every other day, can be plenty of recharging to run a compressor frig with 200ah of lead acid batteries.



I am happy that you are pleased with your absorption frig performance, but very, very, many users of them aren't. I would have to say that the performance level you are talking about, which would be to get more than 60* under ambient inside the frig are way better than any I have personally ever heard about. Most would be very happy if they can get 40* under ambient, but I think many of the frigs spec at about 50*, and we have heard about that in some cases.

[Bud]

Originally Posted by SteveJ

I'm pretty sure that running the genny for two hours will not recharge the battery (ies) unless they are lithiums and running an under hood extra alternator.

The holding tanks on my Roadtrek are good for a week traveling as a couple, two weeks traveling solo. This includes showers/sponge baths, coffee, sweet tea, cooking, washing dishes, toilet flushing and maybe hand washing a few garments until I hit a laundromat.

Apparently you had an absorbtion fridge that had installation and/or mechanical issues. My fridge has been stellar even with temps over 100 degrees, keeping the fridge temps in the safe range. And yes, I have a thermometer inside the fridge.

Please define 'safe range'.

Thanks.

Bud

[SteveJ]

Originally Posted by Bud

Please define 'safe range'.

Thanks.

Bud

Low to mid thirties

[davdent]

Unfortunately opinion sometimes appears to be treated as fact on this forum. Numbers are presented that are not backed up by any reference source and as such should be treated with the utmost suspicion.

The suggestion that an absorption fridge will only cool at most a certain number of degrees below “ambient” (which in itself clearly needs definition) is quite wrong as has been attested to by myself and others.

Also, where did the alternator output come from? What reference is referred to. The number quoted is vastly different from the vehicle we have.

There is clearly a view held by some that the only fridge to have is a compressor fridge. Fine. You are of course entitled to your view.

The reality is that others on this forum have refuted that position based on extended use in harsh conditions.

There are circumstances in which both have advantages. If I had sufficient storage I would go with a 110V fridge using an inverter. The reality is I do not. I have looked at the feasibility of installing LiFePo4 batteries to allow me to do so and have elected to continue with the perfectly functional situation I currently have.

[BBQ]

From the Dometic manual:

OPERATING REFRIGERATOR AT HIGH ALTITUDE

All gas appliances experience lowered efficiency (or rating) at high altitude. This is a direct result of lower atmospheric pressure and oxygen levels, and is not a defect of the refrigerator.

Reduced cooling performance and burner outage may occur at altitudes higher than 5500 feet above sea level (while operating on LP gas). Always operate refrigerator on electric power at altitudes higher than 5500 feet.

[SteveJ]

Originally Posted by BBQ

From the Dometic manual:

I wonder if that's a CYA thing. It's been at least 6 weeks since I've camped at an elevation less than 6í00 feet, ranging up to 9600. The LP has performed normally. The flame fires up right away from the electronic ignition. It just now fired up with no issue. Garmin says I'm at 7024 feet.

[booster]

Originally Posted by davdent

Unfortunately opinion sometimes appears to be treated as fact on this forum. Numbers are presented that are not backed up by any reference source and as such should be treated with the utmost suspicion.

The suggestion that an absorption fridge will only cool at most a certain number of degrees below “ambient” (which in itself clearly needs definition) is quite wrong as has been attested to by myself and others.

Also, where did the alternator output come from? What reference is referred to. The number quoted is vastly different from the vehicle we have.

There is clearly a view held by some that the only fridge to have is a compressor fridge. Fine. You are of course entitled to your view.

The reality is that others on this forum have refuted that position based on extended use in harsh conditions.

There are circumstances in which both have advantages. If I had sufficient storage I would go with a 110V fridge using an inverter. The reality is I do not. I have looked at the feasibility of installing LiFePo4 batteries to allow me to do so and have elected to continue with the perfectly functional situation I currently have.

I can tell you that over the last decade of watching things like the frig temps, you do get a decent idea of what is happening the most, and the 40-50 degree below ambient (ambient is the conditions outside the frig, primarily at the condenser) for an absorption frig is very typical of well running units. I do not ever remember seeing someone say they had unwards of 70* under ambient which the "over 100* and low 30s*" would be. If you and the other poster are getting those temps, that's great, but it is not what we have seen in the past, or what is normally put in "expert" articles about absorption frigs. We had one of the better working absorption units in our Roadtrek, after fixing all the baffling and adding cooling fans, but it was hard pressed to hold under 40* when ambient got over 90*. Of course, if I had the internal temp thermometer close to the evaporator, I could get it to show cooler.


I do personally prefer compressor frigs, for many applications, but not all. You will see a lot of folks recommending changes to compressor frigs because they are replying to posters that are having issues with their absorption frigs and their circumstances would indicate a compressor frig would likely improve their situation. There certainly are situations where absorption frigs are the better choice, and I think most everyone knows that.


There are lots of discussions here of improvements to absorption frig installs that have been done or proposed. Many of them did help, but rarely was the user satisfied with the results over all the varying conditions that we all see.



The alternator output is based on the hundreds, at least, or systems we hear about on here. The "typical" historical class b system for alternator charging would be 50 or 80 amps max in most cases. They would have an isolator or separator controlling the distribution of the power. 50 amp systems wired with #6 wire, the 80 amp systems with #4 wire. They would have 50 or 80 amp breakers on each end. The thing that most people miss is that the alternator size in the vehicle has nearly no effect on the available amps to the batteries with most systems as it is limited by wire size and fusing. What vehicle do you have, and how much does it allow to go to the coach? The "big" battery systems will allow much more power to the coach, and if wired as an engine generator, all the output of that second alternator will be available. Unfortunately, heat takes a toll on the output, so a 250 amp alternator will only net something like 180 amps continuously.


I am glad you have a perfectly working absorption frig, and I am sure many others think the same, and no one said you should change it if you are happy. This does not appear to be the case for many others. As to the alternator output charging, let us in on what you have so we can put the information into our collective knowledge, as the more information we have, the better.


As mentioned earlier, you do not need lithium batteries to run a compressor frig setup, and essentially all the current compressor frigs referred to here are native 12v or 12/110v units, so no inverter needed. The discussion of using an inverter for the frig comes from a recent improvement in the "dorm" frigs to make them as efficient as the marine versions. The dorm frigs would need an inverter if one was used, but AFAIK, no one here has done such a setup yet. There are still questions of durability, venting ease, and even if they are designed to work efficiently in the much higher than in structures temps that RV frig can see.

[Bud]

Originally Posted by booster

I can tell you that over the last decade of watching things like the frig temps, you do get a decent idea of what is happening the most, and the 40-50 degree below ambient (ambient is the conditions outside the frig, primarily at the condenser) for an absorption frig is very typical of well running units. I do not ever remember seeing someone say they had unwards of 70* under ambient which the "over 100* and low 30s*" would be. If you and the other poster are getting those temps, that's great, but it is not what we have seen in the past, or what is normally put in "expert" articles about absorption frigs. We had one of the better working absorption units in our Roadtrek, after fixing all the baffling and adding cooling fans, but it was hard pressed to hold under 40* when ambient got over 90*. Of course, if I had the internal temp thermometer close to the evaporator, I could get it to show cooler.


I do personally prefer compressor frigs, for many applications, but not all. You will see a lot of folks recommending changes to compressor frigs because they are replying to posters that are having issues with their absorption frigs and their circumstances would indicate a compressor frig would likely improve their situation. There certainly are situations where absorption frigs are the better choice, and I think most everyone knows that.


There are lots of discussions here of improvements to absorption frig installs that have been done or proposed. Many of them did help, but rarely was the user satisfied with the results over all the varying conditions that we all see.



The alternator output is based on the hundreds, at least, or systems we hear about on here. The "typical" historical class b system for alternator charging would be 50 or 80 amps max in most cases. They would have an isolator or separator controlling the distribution of the power. 50 amp systems wired with #6 wire, the 80 amp systems with #4 wire. They would have 50 or 80 amp breakers on each end. The thing that most people miss is that the alternator size in the vehicle has nearly no effect on the available amps to the batteries with most systems as it is limited by wire size and fusing. What vehicle do you have, and how much does it allow to go to the coach? The "big" battery systems will allow much more power to the coach, and if wired as an engine generator, all the output of that second alternator will be available. Unfortunately, heat takes a toll on the output, so a 250 amp alternator will only net something like 180 amps continuously.


I am glad you have a perfectly working absorption frig, and I am sure many others think the same, and no one said you should change it if you are happy. This does not appear to be the case for many others. As to the alternator output charging, let us in on what you have so we can put the information into our collective knowledge, as the more information we have, the better.


As mentioned earlier, you do not need lithium batteries to run a compressor frig setup, and essentially all the current compressor frigs referred to here are native 12v or 12/110v units, so no inverter needed. The discussion of using an inverter for the frig comes from a recent improvement in the "dorm" frigs to make them as efficient as the marine versions. The dorm frigs would need an inverter if one was used, but AFAIK, no one here has done such a setup yet. There are still questions of durability, venting ease, and even if they are designed to work efficiently in the much higher than in structures temps that RV frig can see.

booster, you are a nice guy.

Bud

[BBQ]

Originally Posted by SteveJ

I wonder if that's a CYA thing. It's been at least 6 weeks since I've camped at an elevation less than 6í00 feet, ranging up to 9600. The LP has performed normally. The flame fires up right away from the electronic ignition. It just now fired up with no issue. Garmin says I'm at 7024 feet.

Dometic did not say the fridge won't work in high alt.
They posted a "coverall" message.
If your fridge works, that's great. Many people have the same experience.

[Bud]

Originally Posted by SteveJ

I wonder if that's a CYA thing. It's been at least 6 weeks since I've camped at an elevation less than 6í00 feet, ranging up to 9600. The LP has performed normally. The flame fires up right away from the electronic ignition. It just now fired up with no issue. Garmin says I'm at 7024 feet.

Might be more of Dometic just doesn't want the phone calls as things do change with altitude with more 'weak links' showing up with higher altitudes.

I'm good at 10,000. No, better as it is unlikely to be a 100 degrees.

Bud

[Saldar]

Originally Posted by booster

The "typical" historical class b system for alternator charging would be 50 or 80 amps max in most cases. They would have an isolator or separator controlling the distribution of the power. 50 amp systems wired with #6 wire, the 80 amp systems with #4 wire. They would have 50 or 80 amp breakers on each end..... Unfortunately, heat takes a toll on the output, so a 250 amp alternator will only net something like 180 amps continuously.

I've always wondered what size wire is appropriate for charging from the alternator. Can you explain why, if the alternator supplies as much as 180A, the 50 or 80A fuse doesn't blow all the time? Is it the resistance of the wire?

[booster]

Originally Posted by Saldar

I've always wondered what size wire is appropriate for charging from the alternator. Can you explain why, if the alternator supplies as much as 180A, the 50 or 80A fuse doesn't blow all the time? Is it the resistance of the wire?

This is a really good question, as it gets right to the heart of some weaknesses in many/most of the factory alternator systems, especially since the move to AGM batteries from wet cells and to separators from isolators, has picked up speed.



I am the most familiar with the last two (before lithium) Roadtrek systems, so I will use them as examples.


First off, the wire size is determined from a maximum allowable amperage chart or calculator like the one Blue Sea has on their site. The chart will tell you how many amps you can safely carry in your chosen wire gauge. It turns out that #6 wire is about 50 amps and #4 wire is about 80 amps. The alternator size means nothing at this point as this is only wire related. The wire will offer some resistance but not enough to limit charging speed much.


The older Roadtrek systems used #6 wire, and isolator, and a single (or maybe two) wet cell battery. The alternators were in the 120-145 amp range IIRC. Since the wiring was only good for 50 amps safely, they put a 50 amp circuit breaker in the wire to the coach to protect the wire from too much current. This is where the original question comes in---why doesn't the circuit breaker trip if the alternator is that big. The short answer is that the rest of parts gang up and prevent the breaker from tripping or at least not tripping often. The isolator drops the voltage by about .7 volts and wet cells don't accept much current, even when mostly discharged, and they are seeing reduced voltage, so accept less. That is enough to limit the charging to below 50 amps and not trip the breaker.


In the newer versions of the Roadtrek systems they use #4 wire, a separator, and two AGM batteries. The alternators are similar, although there are also some bigger ones near 200 amps. This wiring will be safe at 80 amps so they use an 80 amp breaker to protect the wiring in these setups. Now again we are at the original question, but we get a different answer. The separator does not drop the voltage to the coach like the isolator does. Two AGM batteries, even if not discharged very far, will accept much more than the 80 amps the wiring can handle. In this case the circuit breaker will trip while charging, and even worse, it will cycle on and off as it heats and cools, until the batteries are full enough to limit the current to them. The are automatic reset breakers so they do fine at protecting things, but wear out or stick, giving issues. We do occasionally get questions from folks that have good hearing that they hear a periodic clicking sound as they drive, but every drive. It is almost always the circuit breakers in the newer systems. The bad is that it is not right to be current limiting by cycling a circuit breaker as they can fail shut and overload the wiring, causing a fire or other damage.



There are fixes for these things, but nobody really does them, and just lives with the occasional breaker replacement, which is fine if they fail open, but not so fine if they fail shut and quit protecting. In Roadtreks there are usually two breakers, one on each end of the cable, so it would be rare to get a dangerous condition as both would have to fail shut, but I am sure it happens.


Limiting the current from the alternator to the coach is not a cheap easy fix, but can be done with off the shelf parts. They make various sized DC to DC battery chargers that you can put in the cable to coach that will limit current to their rating amps. The bonus is that they also will give you a multistep charge profile instead of the always at high voltage alternator voltage, so batteries should last longer. I think the DC to DC chargers are a very good thing to have, especially if you have long drive days where you have full alternator voltage on full AGM batteries for long periods. AGMs don't like that, and can get dried out and shorten life.


Note that Roadtrek had variations of the the two systems mentioned, too, with more or less batteries and mixing of the mentioned parts, so you have to check out what you really have to know.


Engine generator systems are similar, but need to limit current sometimes, so handled differently.

[Roadtrek Adventuous RS1]

Originally Posted by booster

I can tell you that over the last decade of watching things like the frig temps, you do get a decent idea of what is happening the most, and the 40-50 degree below ambient (ambient is the conditions outside the frig, primarily at the condenser) for an absorption frig is very typical of well running units. I do not ever remember seeing someone say they had unwards of 70* under ambient which the "over 100* and low 30s*" would be. If you and the other poster are getting those temps, that's great, but it is not what we have seen in the past, or what is normally put in "expert" articles about absorption frigs. We had one of the better working absorption units in our Roadtrek, after fixing all the baffling and adding cooling fans, but it was hard pressed to hold under 40* when ambient got over 90*. Of course, if I had the internal temp thermometer close to the evaporator, I could get it to show cooler.


I do personally prefer compressor frigs, for many applications, but not all. You will see a lot of folks recommending changes to compressor frigs because they are replying to posters that are having issues with their absorption frigs and their circumstances would indicate a compressor frig would likely improve their situation. There certainly are situations where absorption frigs are the better choice, and I think most everyone knows that.


There are lots of discussions here of improvements to absorption frig installs that have been done or proposed. Many of them did help, but rarely was the user satisfied with the results over all the varying conditions that we all see.



The alternator output is based on the hundreds, at least, or systems we hear about on here. The "typical" historical class b system for alternator charging would be 50 or 80 amps max in most cases. They would have an isolator or separator controlling the distribution of the power. 50 amp systems wired with #6 wire, the 80 amp systems with #4 wire. They would have 50 or 80 amp breakers on each end. The thing that most people miss is that the alternator size in the vehicle has nearly no effect on the available amps to the batteries with most systems as it is limited by wire size and fusing. What vehicle do you have, and how much does it allow to go to the coach? The "big" battery systems will allow much more power to the coach, and if wired as an engine generator, all the output of that second alternator will be available. Unfortunately, heat takes a toll on the output, so a 250 amp alternator will only net something like 180 amps continuously.


I am glad you have a perfectly working absorption frig, and I am sure many others think the same, and no one said you should change it if you are happy. This does not appear to be the case for many others. As to the alternator output charging, let us in on what you have so we can put the information into our collective knowledge, as the more information we have, the better.


As mentioned earlier, you do not need lithium batteries to run a compressor frig setup, and essentially all the current compressor frigs referred to here are native 12v or 12/110v units, so no inverter needed. The discussion of using an inverter for the frig comes from a recent improvement in the "dorm" frigs to make them as efficient as the marine versions. The dorm frigs would need an inverter if one was used, but AFAIK, no one here has done such a setup yet. There are still questions of durability, venting ease, and even if they are designed to work efficiently in the much higher than in structures temps that RV frig can see.

I can tell you that over the last decade of watching things like the frig temps, you do get a decent idea of what is happening the most, and the 40-50 degree below ambient (ambient is the conditions outside the frig, primarily at the condenser) for an absorption frig is very typical of well running units. I do not ever remember seeing someone say they had unwards of 70* under ambient which the "over 100* and low 30s*" would be. If you and the other poster are getting those temps, that's great, but it is not what we have seen in the past, or what is normally put in "expert" articles about absorption frigs. We had one of the better working absorption units in our Roadtrek, after fixing all the baffling and adding cooling fans, but it was hard pressed to hold under 40* when ambient got over 90*. Of course, if I had the internal temp thermometer close to the evaporator, I could get it to show cooler.

This is perfectly consistent with what we're experiencing.....it's over 100 to 105 degrees here and seeing temps around 55 degrees or so inside the refrigerator .......

Surprisingly, when I called Roadtrek to inquire whether they installed "cooling fans" they said that they didn't do that and were kinda wondering why not.....the representative said he would raise the issue internally.....I said... maybe it's not that "hot" in Canada...he said it does get hot in Southern Ontario....

At any rate.....I'm going to look at getting a cooling fan .... we'll see how that works.....

In the meantime....now I know that no propane at higher altitudes...mine says 3,280... maybe the newer models are 5,500 ??

IF...I intend to do more boondocking.....I either need to get more solar panels for charging my system or just skip it and find shore power........

I'm glad I don't live in the van...... it's pretty nice... but , my house is nicer.......

[peteco]

[QUOTE Surprisingly, when I called Roadtrek to inquire whether they installed "cooling fans" they said that they didn't do that and were kinda wondering why not.....the representative said he would raise the issue internally.....I said... maybe it's not that "hot" in Canada...he said it does get hot in Southern Ontario....

At any rate.....I'm going to look at getting a cooling fan .... we'll see how that works.....
[/QUOTE]

There is more to getting an absorption fridge to work well in hot weather than just a fan on the condenser coils. Below is a writeup on my attempts to get my absorption fridge to work properly.

The Dometic RM2554 refrigerator in my 2006 Roadtrek 210P had poor performance in hot weather with fridge temperatures into the mid or upper 40’s in hot weather. The freezer was good at near 0-degrees. The fridge worked a little better on gas than electric. So I started searching the internet and read the Dometic installation and service manuals to try to figure out if the refrigerator had failed or if there was a fixable problem. I will describe the steps that have made the fridge performance acceptable, though it does struggle sometimes in hot weather with temperatures going up to about 40-41 degrees. The refrigerator will get to the mid-30s in more moderate temperatures below about 85 degrees.

I checked the AC heater resistance and it met specs. I hooked the heater up directly to AC and there was no improvement.

I bought a fan called the Snyder fan system, which helped a little. The Snyder setup is no longer available, but I think there is a better fan setup than this that I will describe later.

The Dometic installation and service manuals showed that the vent area behind the fridge needs to be configured properly to get adequate venting. Roadtrek did not install the proper vent cavity setup. I do not know if Roadtrek has fixed the vent setup on the newer models. I installed an inner wall to eliminate the large gap between the van sidewall and the fridge coil system. I also put some foam insulation between the Van wall and this new inner wall to reduce solar heating of the outside wall from heating the vent cavity. The Dometic manual also says you can use a wall baffle but I thought the inner wall mod would work better. I also made an upper baffle as shown in the manual. I installed another fan as shown in the manual. The performance improved somewhat.

I had some inconsistent operation with the control board so I replaced it with a Dinosaur board.

Replacement boards for Dometic

APRV has some good information regarding problems with sidevent setups like our Roadtrek’s. I bought the APRV control unit and one of their fans. The APRV control unit protects the refrigerator from overheating caused by off-level operation, and also can control a vent fan. I installed the fan in the upper vent to pull air through the vent cavity.

https://www.arprv.com/rv-fridge-slide-out.php

I try to park the Roadtrek so the fridge side is shaded if possible. I have also made a small shade that attaches with suction cups to the outside of the Roadtrek to shade the refrigerator area and reduce solar heating.

I try to not put hot foods or a lot of room temperature items in at one time. I keep two small blue ice freeze bricks in the freezer, and I put these in the refrigerator compartment in hot weather during the day, and return them to the freezer at night.

I also have one of the small blue battery fans that blows air over the evaporator fins inside the fridge. This helps, but I may try some 12-volt fans that should give better airflow.

I think the cumulative effect of all these mods has brought the performance of the fridge to an acceptable level. I think the upper fan installation and bringing the vent cavity to Dometic specs had the most effect.

Another option is to have the cooling unit replaced. I have talked to Leon Herschberger at National RV Refrigeration in Indiana. He was very knowledgeable on the RV refrigerators and has rebuilt cooling units that sound like they are better than the Dometic original unit. If I were going to have my unit repaired I would strongly consider driving to his location.

National RV Refrigeration National RV Refrigeration
260-768-7059.
Leon Herschberger
5335 N SR 5
Shipshewana, Indiana 46565

I have read that some have had success remove the fridge and turning it upside down to “burp”. They claim they have had good fridge performance as a result.
Two-Way Refrigerator? - Page 8 - Airstream Forums

When this fridge fails completely, another option is to replace it with a compressor model. This would also require electrical system upgrades.