Dometic 3 Way Refrigerator System

Mein Sprinter

2010 Roadtrek SS Agile
Hello all Roadtrekers

I am sure this has been posted somewhere but cannot find it.

It's in regard to the Dometic AC/Propane/DC refrigerator system. What we noticed when the compressor/evaporator system gets hot the dual fans do not kick in in order to cool! Mines a 2010 Roadtrek Agile which still has the old system. Any ideas of what to check to make sure that the fans kick in at a certain temperature to cool the coils. My fans are dusty, stagnant where I think they have never operated.

Thank you

Cheers..
 

BobLLL

Member
Well, they are 12 volt fans, so you could connect them directly to a battery to see if they turn. But the wiring is a bit hard to access as I recall. If the fans work when directly connected to a battery, then the temperature switch/relay may have failed. That thing is stuck somewhere behind the fins as I recall. If you can't find it, let me know I shall go look at mine.

For what it is worth, I put a thermometer above the fins with the cover off, and found my fans turn on at an air temperature of about 150 degrees and off at 120 degrees. They only run in hot weather. But I'm sure you have plenty of hot weather available for testing.
 

Mein Sprinter

2010 Roadtrek SS Agile
Well, they are 12 volt fans, so you could connect them directly to a battery to see if they turn. But the wiring is a bit hard to access as I recall. If the fans work when directly connected to a battery, then the temperature switch/relay may have failed. That thing is stuck somewhere behind the fins as I recall. If you can't find it, let me know I shall go look at mine.

For what it is worth, I put a thermometer above the fins with the cover off, and found my fans turn on at an air temperature of about 150 degrees and off at 120 degrees. They only run in hot weather. But I'm sure you have plenty of hot weather available for testing.
Thank you Boblll... you have rescued me often times without thanks—— blame the internet connection. We’re in the wilds of Montana and I need to cool my fly fished trouts. Okay, will get at it when the sun sets. Thank you again.
cheers...
 

BobLLL

Member
Ah, fresh trout, mmmm. So this is a serious issue.

You shouldn't need the fans in Montana, especially at night. The fans only seem to run on hot days.

The best way to tell for sure whether a fridge is working is to put a thermometer in the fridge. An electronic cooking thermometer with a probe on the end of a wire is a handy diagnostic tool, you can leave the probe inside the fridge and check the temp without opening the door. The one I have goes down to 32 deg. F, so it is adequate for checking a fridge but not a freezer.

I had the "pleasure" of troubleshooting a problem with mine a couple of years ago, and I made some temperature notes for future reference. I took the freezer door and divider out, so the whole box is a refrigerator. If you have the freezer in, your temps may be different.
With setting temp setting 4 lights, gas will maintain 37-41 degrees with 80 degree outdoor temp.
Open door a few minutes. Then close the door. Should recover to 41 in less than 30 minutes after closing door.
(Again, I think this was on an 80-degree day.)
Temperature setting 3 seems like about 41-45 degrees, but not tested as much.
Booster fans come on at ~150deg at top of fins, off at ~120.
 

SSTraveler

2014 LTV Unity Murphy Bed
I found that the thermodisc switch being set not to kick the fans on until 150° is just to high a setting to really help the Refrigerator in it's cooling process. In fact, I don't think my fan ever even turned on. I remove the thermodisc and rewired the OEM fan to more fans and added a temperature controller all on their own 12v power supplies. It's important to get airflow across the condenser at just the right temperature in the chemical process to improve the cooling process. I attached the temperature controller sensor to the condenser inlet and set the controller to kick the fans on at 132° and off at 118°. Here is a thread you may find helpful, https://sprinter-source.com/forums/index.php?threads/61435/#post-608154. I've posted a lot on my saga to improve the Dometic 3 way performance so if you search for my posts you'll get a lot of information. But last summer I threw in the towel and replaced it with a Isotherm Cruise 219 compressor Refrigerator, on love it. Now I have a Refrigerator I can trust and keeps my beverages/food cold just like you would expect. I've posted a lot on my Isotherm experience as well.
 
Last edited:

irvingj

2015 RT SS Agile (3.0L)
Ditto on the compressor fridge. We had a small teardrop with the 3-way Dometic... most of the time it worked, but that type of system has trouble when it's hot out. Not so with the one we have in our SS Agile. Newer 12v compressor refrigerators are quite efficient in their use of electricity; we leave ours on 24-7 when on the road and almost never "plug in." We do, however, have 300W of solar and 4 ea. 6V coach batteries.
 

Mein Sprinter

2010 Roadtrek SS Agile
Hi guys... awesome info. We’re most often beyond internet connection but will respond and tell you what I plan to do. My roof top AC now also shatters when fan is turned on high. Had to use AC while parked at food store due to our Dachshund. It was 104F in Granville, ID. Lost 5 Trout.... caught 3 Trout but always released them.
 

Mein Sprinter

2010 Roadtrek SS Agile
Achtung Trek guys.... got home Okay with a malfunctioning AC snd poor cooling Dometic refrigerator.. Survived all okay tho! Had 8 Trout strikes and 5 hooked but released, could not coup de grace these beautiful fish. Fished in every State: Nevada, Idaho, Montana, Wyoming... not in Colorado, NM and AZ. Enuff said.

Okay, we decided to upgrade the AC and Refrigerator instead of fixes. BobLLL and others what do you recommend regarding the refrigerator: stay with the 3 way Dometic brand ?( 10 year old Dometic is wired for 3 way) : driving, its on DC; RV campgrounds(very seldom) its AC; off grid, BLM, its propane(16 gal). If battery and AC.. i don't have room for more batteries as I got a 144". Please advise :thumbup:

Now the AC, also 10 years old...(Dometic 640315C Penguin II 410 Amp Low Profile)...is this a good one??

Thank you all for your suggestion and advice.

Cheers...
 

BobLLL

Member
Just out of curiosity, is the fridge performance poor on electric mode too, or just gas?
 

BobLLL

Member
As to whether an electric-only fridge will work for you, it seems to depend on camping style. If you usually drive every day, it is my impression that battery capacity of our rigs will be sufficient. If you generally camp off the grid and off the road for more than a day or two at a time, you probably will need to run the generator. But I haven't run the numbers on how often this would be required. For anyone who wants to chime in, these coach batteries are AGM with a total 20 hour rating of 210 amp-hours.
 

SSTraveler

2014 LTV Unity Murphy Bed
I love my Isotherm Cruise 219 compressor refrigerator, only 45a/24 hours used, and it runs great in 100+ temperatures. I have a Penguin ll and its been running great for over 6 years now. If it ain't broke don't sweat it now. Definitely dump the 3 way Dometic for a compressor refrigerator! My only regret is that I didn't dump the Dometic sooner!
 

Mein Sprinter

2010 Roadtrek SS Agile
Just out of curiosity, is the fridge performance poor on electric mode too, or just gas?
Hi BobLLL... it's poor on all selections! Gas, I can understand due to elevations and proper chassis alignment (flame straight up the chimney). He, he, our ref door even flew off doing a hairpin turn... It's OLD plastic and the hinges have deteriorated. It's been duct taped now and then.
Best cooling is of course AC when RV camp grounding which we seldom do (laundry and hot shower only-once a week).

cheers...
 

Mein Sprinter

2010 Roadtrek SS Agile
As to whether an electric-only fridge will work for you, it seems to depend on camping style. If you usually drive every day, it is my impression that battery capacity of our rigs will be sufficient. If you generally camp off the grid and off the road for more than a day or two at a time, you probably will need to run the generator. But I haven't run the numbers on how often this would be required. For anyone who wants to chime in, these coach batteries are AGM with a total 20 hour rating of 210 amp-hours.
Correct BobLLL... my AGMs are similar as yours-210... propane gen needs to be run for an hour in order to replenish electrical needs. We're pretty frugal.. don't need much... but good refrigeration is needed for the SHMBO who likes to cooks and prepares bons plats français in the middle of nowhere!

cheers...
 

Mein Sprinter

2010 Roadtrek SS Agile
I love my Isotherm Cruise 219 compressor refrigerator, only 45a/24 hours used, and it runs great in 100+ temperatures. I have a Penguin ll and its been running great for over 6 years now. If it ain't broke don't sweat it now. Definitely dump the 3 way Dometic for a compressor refrigerator! My only regret is that I didn't dump the Dometic sooner!
Thank you, SSTraveler. I'll have a heavy look at the Isotherm. Did you have to add additional batteries? I only have room for my current engine compartment ..6v-210amp AGMs. No solar!! But do have a propane generator that could replenish !!?? While we very seldom use the A/C as we almost always travel at higher, cooler latitudes of Canada (closed to us USA residents). We were to head to Yellowknife; not this year.

cheers...
 

Mein Sprinter

2010 Roadtrek SS Agile
I love my Isotherm Cruise 219 compressor refrigerator, only 45a/24 hours used, and it runs great in 100+ temperatures. I have a Penguin ll and its been running great for over 6 years now. If it ain't broke don't sweat it now. Definitely dump the 3 way Dometic for a compressor refrigerator! My only regret is that I didn't dump the Dometic sooner!
SSTraveler...can you provide me the exact Isotherm Cruise 219 compressor ref model # ? and does it fit into the cave of the old Dometic 8501 cavity?

Thank you

Cheers...
 

SSTraveler

2014 LTV Unity Murphy Bed
Thank you, SSTraveler. I'll have a heavy look at the Isotherm. Did you have to add additional batteries? I only have room for my current engine compartment ..6v-210amp AGMs. No solar!! But do have a propane generator that could replenish !!?? While we very seldom use the A/C as we almost always travel at higher, cooler latitudes of Canada (closed to us USA residents). We were to head to Yellowknife; not this year.

cheers...
No more batteries needed, I only have two 6v-210ah of AGM batteries as well. But I do have 200w of solar, which certainly helps during the day and sends you into the evening with full batteries. The generator is good for recharging as well, just noisy. You can expect to use less amp hours than mine does because you'll be installing a smaller Refrigerator with a smaller compressor. I installed the Isotherm Cruise 210, which is a much larger Refrigerator (max current of 6a and an average of 2.5a). The Isotherm makes a couple of Refrigerators that would fit the Dometic 8501 dimensions (32.32"h x 20.59"d x 21.4"d), the Isotherm Cruise 100 (29.3 x 19.1 x 17.9), Freeline 115 (31.5 x 20.7 x 21.5), Cruise 130 (29.6 x 20.7 x 21.4) and possibly the Big 90 Classic (33.5 x 18.7 x 16.8). These smaller Refrigerators have a BD35F sized compressor, which uses even less amps (Current Draw: Compressor Running: 4.7 - 5.0 Amp @ 12 Volt DC and an Average: 1.2 Amp @ 12 Volt DC than mine with the BD50F, larger displacement compressor. You can view the details on the Isotherm website, https://www.indelwebastomarine.com/...arge-fridges-115-160-l/freeline-115-elegance/. Here is my install starting on post #62, https://sprinter-source.com/forums/index.php?threads/34762/page-4#post-790487, but there are others who have installed Isotherm, https://sprinter-source.com/forums/index.php?threads/69774/ or https://sprinter-source.com/forums/index.php?threads/46644/page-4#post-453875. The key difference in the installation between and adsorption and compressor Refrigerator is that the Refrigerator is not exposed to any outside temperatures, you'll need to close off your exterior vents. However if you only camp in less than 89.6° outside temperature climates then the compressor Refrigerator may perform fine exposed to the outside temps, you may just need to add a vent exhaust fan to ensure no only the heat generated by the compressor gets exhausted but that cooler air is pulled across through the back of the Refrigerator. Since the Isotherm has an exhaust fan at the compressor, I'd add a 120mm 12v fan to the top exterior vent to pull more air through the back of Refrigerator space. Connect the fan to it's own 12v power supply with a 2a fuse. I have my fan on a switch. I had to close off my vents because I mostly camp in 100° weather with AC so the Refrigerator perform great in my interior AC controlled climate of 75-80°. You may also find this size comparison tool helpful, https://www.suremarineservice.com/Galley/Refrigeration-Size-Comparison/. Indel/webasto not only makes Isotherm, but Vitrifrigo and Truckfridge Refrigerators as well, all using DanFoss compressors.
 
Last edited:

Mein Sprinter

2010 Roadtrek SS Agile
No more batteries needed, I only have two 6v-210ah of AGM batteries as well. But I do have 200w of solar, which certainly helps during the day and sends you into the evening with full batteries. The generator is good for recharging as well, just noisy. You can expect to use less amp hours than mine does because you'll be installing a smaller Refrigerator with a smaller compressor. I installed the Isotherm Cruise 210, which is a much larger Refrigerator (max current of 6a and an average of 2.5a). The Isotherm makes a couple of Refrigerators that would fit the Dometic 8501 dimensions (32.32"h x 20.59"d x 21.4"d), the Isotherm Cruise 100 (29.3 x 19.1 x 17.9), Freeline 115 (31.5 x 20.7 x 21.5), Cruise 130 (29.6 x 20.7 x 21.4) and possibly the Big 90 Classic (33.5 x 18.7 x 16.8). These smaller Refrigerators have a BD35F sized compressor, which uses even less amps (Current Draw: Compressor Running: 4.7 - 5.0 Amp @ 12 Volt DC and an Average: 1.2 Amp @ 12 Volt DC than mine with the BD50F, larger displacement compressor. You can view the details on the Isotherm website, https://www.indelwebastomarine.com/...arge-fridges-115-160-l/freeline-115-elegance/. Here is my install starting on post #62, https://sprinter-source.com/forums/index.php?threads/34762/page-4#post-790487, but there are others who have installed Isotherm, https://sprinter-source.com/forums/index.php?threads/69774/ or https://sprinter-source.com/forums/index.php?threads/46644/page-4#post-453875. The key difference in the installation between and adsorption and compressor Refrigerator is that the Refrigerator is not exposed to any outside temperatures, you'll need to close off your exterior vents. However if you only camp in less than 89.6° outside temperature climates then the compressor Refrigerator may perform fine exposed to the outside temps, you may just need to add a vent exhaust fan to ensure no only the heat generated by the compressor gets exhausted but that cooler air is pulled across through the back of the Refrigerator. Since the Isotherm has an exhaust fan at the compressor, I'd add a 120mm 12v fan to the top exterior vent to pull more air through the back of Refrigerator space. Connect the fan to it's own 12v power supply with a 2a fuse. I have my fan on a switch. I had to close off my vents because I mostly camp in 100° weather with AC so the Refrigerator perform great in my interior AC controlled climate of 75-80°. You may also find this size comparison tool helpful, https://www.suremarineservice.com/Galley/Refrigeration-Size-Comparison/. Indel/webasto not only makes Isotherm, but Vitrifrigo and Truckfridge Refrigerators as well, all using DanFoss compressors.
Many, many thank yous for your information. :thumbup:

Cheers...
 

Top Bottom