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My DC Compressor Fridge conversion in progress

toddb
Explorer
Explorer
I'd though I'd share my experience swapping out my refer. The camper is an AF 992 with a norcold N621 fridge. The fridge worked good while parked, with good fans and shrouds I could manage 36-38 in the fridge until about 101*. Going down the road though it was less than ideal, I never seen a flame blow out but on flat ground it was low 40s, hills into the 50s.

So after reviewing options the conversion kit seemed like the best choice, bang for the buck. At $770 it's a steal with a little labor compared to replacing the entire fridge.

I wanted to pull the fridge and put and do this in the garage, but I found out the fridge wasn't going to fit through the door. Had to be done in the camper...cramped for sure. So getting the fridge out was a challenge due to it's mid ship placement, it squeezed thought the dinette and bathroom door though with 0 clearance.



Refer is out, popped out pretty easy. Cleaned up of all the thermal mastic.

The two beside each other. This is actually the failed compressor unit, more on that later.

So following the you tube videos, (those are the instructions) I installed the compressor unit and let the unit sit for 24hours.



Upon starting the fridge the compressor shook pretty bad so I shut it down. I verified wiring and mounting and started it again, same thing. I tried calling the manufacturer but in several attempts all I got was a full voicemail box. So I emailed. I read nothing but good things about the customer service but emailing seems the only way they want to communicate. With a 12-24hr response time resolving this was a lot slower than I wanted. I suspected the compressor was damaged in shipment breaking the internal motor mounts. I tried several things to mitigate the vibration but it sounded like a helicopter landing on top of the camper while standing inside. So after getting them videos they agreed it wasn't normal and shipped another to me. No labor day camping trip for us ๐Ÿ˜ž

So I got to do this again, and it's hot and sticky here...yeah!

The new unit arrived, fedex does a great job of testing packaging btw. I stood this unit upright over night and bench tested it before I went through all of trouble. Compressor fired up and was very smooth. The old new unit is spray foamed into a foam fridge and I had to cut it out. Once out and cleaned up the new one went in pretty fast and I loosely mounted it until I could start it up the next day.

So it's hot here, I started the fridge at about 7am 88* the entire fridge drawing 6.75A. I'll have to go back and test just the compressor. I concluded the cool down around 1:30p, it was 108 outside, coach was 106. The fridge made it down to 43 on the data logger placed on the second shelf down. My wireless thermometer was showing 42.6. The freezer with IR was 3.5*. Looks like it took about 3 hours to reach the temp.


Fridge fan setup:


I'll do more testing later, next week is supposed to be cooler..I hope.

*Moderator switched URL tags to IMG and set image width
31 REPLIES 31

toddb
Explorer
Explorer
Well I got this squared away and was able to test it. The problem with the temp stall was how notcold measures the temp. The fins get super cold with the compressor fast, since the thermistor is directly on the fin it was short cycling the compressor and the fridge wouldn't come down more. I pulled it off and let it hang just in front of the fins.

Fridge set on 2: Temps recorded by the wireless thermometer.
Started the night before and let run.
Time fridge freezer outside batt soc
8am 36.1 12.7 85.6 75.6
9am 35.1 6.6 85.6 72.6
I bumped the temp to 3 at 9am
9:50 34.7 5.4 90.7 66.4
11:40 34.9 3.7 98.6 57.7

I moved the camper out of the carport to see how well my solar panels would keep up. Not a great solar day, many low puffy clouds.
12:05 turned solar on battery at 57.3 soc fridge set to 1 to try and maintain 38-40*.
13:00 37.2 battery died 95.9 61.7
14:00 38.8 " 97.7 68.2
15:00 38.8 10.9 99.5 73.8
16:00 38.8 7.7 98.2 77.1
17:00 37.9 6.1 95.0 78.0

Compressor speed set with 270ohm resistor and I printed a fan shroud that helped with subcooling.

StirCrazy
Moderator
Moderator
c.traveler2 wrote:
StirCrazy wrote:
SidecarFlip wrote:
The one I'm looking at, max draw is 6.5 amps at 100% duty cycle but less than 1.2 amps cycling.



is there any stats on how many Ah one of these fridges would draw over a 24 hour period? would be nice to see something say at a 40 degree cabnet temp in 90 degree weather parked in the sun it used so many Ah.

Steve


I have this refrigerator Dometic CR1110, this link has some information that may answer some of your questions but on my unit.

Dometic CR1110


This refrigerator will stay below 40 degrees on days that are over a 100.


it half answers ut, they show comparison in percentage of running time, then they give you average amps, but they don't list the amps of it running full out. but it does give me and idea, thanks

Steve
2014 F350 6.7 Platinum
2016 Cougar 330RBK
1991 Slumberqueen WS100

Geewizard
Explorer
Explorer
SidecarFlip, which model of Demetic Cool Box do you have?
2021 Winnebago Micro Minnie 1708FB
2014 Toyota Tundra Double Cab
300W solar, MPPT controller, LED lights
Xantrex Freedom X Inverter 3000W
2 Fullriver 105AH AGM batteries
Air Lift WirelessAIR and air bags
Hankook Dynapro ATM 10-ply tires

Geewizard
Explorer
Explorer
SidecarFlip wrote:
Geewizard wrote:
996Pilot wrote:
When I replaced mine in my 2006 Outfitter Apex 8 I went with an Isotherm unit. Same exact footprint as my Nocold but 45% more refrigerator space. I had to play some tricks getting it into the camper but it was worth it.


I replaced mine in my 2004 Outfitter Apex 8 with the Tundra T42. The cutout was almost the same. I had to remove the door and frame to swap them out but no big deal. Absolutely worth it. I bought mine from Sure Marine Service in Seattle in about 2005.

Nice comparison chart: https://www.suremarineservice.com/Galley/Refrigeration-Size-Comparison/


Excellent pricing on Dometic Marine units btw.


Yes, they have great prices.
2021 Winnebago Micro Minnie 1708FB
2014 Toyota Tundra Double Cab
300W solar, MPPT controller, LED lights
Xantrex Freedom X Inverter 3000W
2 Fullriver 105AH AGM batteries
Air Lift WirelessAIR and air bags
Hankook Dynapro ATM 10-ply tires

SidecarFlip
Explorer III
Explorer III
I would have used expanded foam block insulation, Lord knows I have plenty 3" left over from my in floor heating project I installed when I added on to the machine shop last year (PEX) but rigid foam, while nice, there was not enough room to get free access to the sides. Remember, it's not an open wall, just to access covers.

I sure do like floor heat though. it gets real cold here in the winter and a 65 degree floor is nice on the feet.

Your situation is different than mine is. You primarily camp in campgrounds where you have a pad or graded parking spot so levelling your TC is easier. My wife and I camp primitive all the time and it's rare that where I set down at, that the ground is level. That aspect alone makes a compressor fridge very attractive. If a Dometic compressor fridge works as well as the cool box we now have, it's a winner for us. Camping in the woods or a turnout is a lot different than a campground and why I always have my genny with me.
2015 Backpack SS1500
1997 Ford 7.3 OBS 4x4 CC LB

Kayteg1
Explorer II
Explorer II
Fiberglass pushed hard to compact is loosing its R value.
You want good insulation, get polyurethane sheets, who come in different thickness at HD. Their R value is about 3 times the fiberglass.
Coolers are hard to judge.
We have 1 which we bought over 30 years ago. Very convenient with storage in the top for plates and utensils, but it looks old-fashion comparing to today's coolers. Still I was carrying frozen steaks in it, while having it in the cab and after 12hr trip the steaks were still frozen.
Newer coolers are nothing close.
When compressors by its own offer better efficiency, than absorption, there is much more to make efficient refrigerator.
I did test 2 years ago and my absorption fridge can come down to 0F (at night) in 100F temperatures (at day), so I am not looking for replacement.

SidecarFlip
Explorer III
Explorer III
I don't have an issue running my inverter genny to take up the slack. I'm 'green' but not that green...lol

I still think (maybe I'm all wet) that the more insulation you have between the cabinet the fridge is housed in and the fridge itself, the more efficient it is. I know the first year I had my TC, I was really dismayed with the Amish fridge's inability to keep food even cool so I was about to add 2 fans in the upper cavity (mine intakes and exhausts out the side, not through the roof and when I pulled the outside vent covers off to add two computer fans and saw what the builder didn't do, I was not happy. NO insulation between the fridge cabinet and the enclosure at all and they forgot to add the Dometic required curved baffle at the top though they did install a cheap sleeve bearing fan that was doing nothing but circulating warm are from the boiler and HX throughout the space where the insulation should have been, but wasn't.

I trundled down to Lowes and bought a roll of unfaced pink stuff and a sheet of light gauge galvanized metal and headed home. Stuffed almost the entire roll of unfaced pink stuff between the outer cabinet and the fridge (wearing gloves and a face mask of course, the stuff is itchy). Once I stuffed the void, I went in my shop and sheared the galv sheet to size and roll formed it to the curve I needed to make a baffle for the top of the cooling unit to direct the air flow. The, I added 2 air bearing computer fans (250 cfm each) to the upper vent and used the already in place thermostatic switch to power them. Made a huge difference in the operation of the fridge, it actually refrigerated, what a concept. My issue (and why I'm going to a compressor fridge is) we mostly primitive camp, usually off road and it's extremely hard to get the fridge level enough to operate correctly. Not an issue with a compressor fridge and even though my Amish fridge actually works now, it still takes quite a while to cool down from ambient whereas a compressor fridge will cool down in a couple hours not a day or longer (depending on how hot it is outside).

We already own a Dometic Cool Box and it sits on the floor in the truck cab when we go camping and in my wife's car when she goes grocery shopping. She uses it to bring home frozen food without becoming unfrozen in the summer, we live 30 minutes from the grocery store. She don't even turn it on until she goes to go in the store and when she comes out and puts the frozen food inside, it stays frozen coming home and when we go camping, stuff we need to stay frozen go in it, like ice cream and you don't have to worry if it's frozen or turned to mush in an Amish fridge with it's temperature swings. I'm 100% sold on the Cool Box and I know it will be a winner in the TC as well. Not familiar with the other brands but I'm sure they are just as good so long as they employ the Waeco / Danfoss duty cycle compressor.
2015 Backpack SS1500
1997 Ford 7.3 OBS 4x4 CC LB

SidecarFlip
Explorer III
Explorer III
Geewizard wrote:
996Pilot wrote:
When I replaced mine in my 2006 Outfitter Apex 8 I went with an Isotherm unit. Same exact footprint as my Nocold but 45% more refrigerator space. I had to play some tricks getting it into the camper but it was worth it.


I replaced mine in my 2004 Outfitter Apex 8 with the Tundra T42. The cutout was almost the same. I had to remove the door and frame to swap them out but no big deal. Absolutely worth it. I bought mine from Sure Marine Service in Seattle in about 2005.

Nice comparison chart: https://www.suremarineservice.com/Galley/Refrigeration-Size-Comparison/


Excellent pricing on Dometic Marine units btw.
2015 Backpack SS1500
1997 Ford 7.3 OBS 4x4 CC LB

c_traveler2
Nomad
Nomad
StirCrazy wrote:
SidecarFlip wrote:
The one I'm looking at, max draw is 6.5 amps at 100% duty cycle but less than 1.2 amps cycling.



is there any stats on how many Ah one of these fridges would draw over a 24 hour period? would be nice to see something say at a 40 degree cabnet temp in 90 degree weather parked in the sun it used so many Ah.

Steve


I have this refrigerator Dometic CR1110, this link has some information that may answer some of your questions but on my unit.

Dometic CR1110


This refrigerator will stay below 40 degrees on days that are over a 100.
2007 F-250 4x4 /6.0 PSD/ext cab/ 2020 Bunduvry

Lance 815/ 85 watts solar panel (sold)
2020 Bunduvry by BundutecUSA

Travelingman2 Photo Website
Truck Camper Trip Reports 3.0
travelingman21000 YouTube Videos
Alex and Julie's Travels Blog

JimK-NY
Explorer II
Explorer II
I have 2 x 135 watt panels. This past year I traveled from mid August through the end of November. There were a lot of days where the solar did not keep up due to low sun angle, short days, shade and clouds. I was pretty much OK until I needed to use the furnace even minimally.

StirCrazy
Moderator
Moderator
JimK-NY wrote:
StirCrazy wrote:
SidecarFlip wrote:
The one I'm looking at, max draw is 6.5 amps at 100% duty cycle but less than 1.2 amps cycling.



is there any stats on how many Ah one of these fridges would draw over a 24 hour period? would be nice to see something say at a 40 degree cabnet temp in 90 degree weather parked in the sun it used so many Ah.

Steve


I have a small (4 cu ft) NovaKool with a Danfoss compressor. When the ambient temp is around 70 degrees or less it does a great job pull 2-3 amps with about a 1/3 duty cycle. That is about 20 or so AH per day. When the temps increase to the upper 80s or 90 degrees, the unit runs almost continuously. It keeps internal temp pretty well but chews up 60-75 AH per day. My solar system has 300 AH of AGM batteries so I am good for only 2 days in the shade or 2 days of clouds. Even with full summer sun my panels are not big enough to replenish the system with a full day of charging. Compressor refrigerators definitely have a downside.


how big is your solar, I have 480watts of panels and 470AH of batteries in my 5th wheel, want to put as much as I can on my TC when I find the one I like.

Steve
2014 F350 6.7 Platinum
2016 Cougar 330RBK
1991 Slumberqueen WS100

JimK-NY
Explorer II
Explorer II
StirCrazy wrote:
SidecarFlip wrote:
The one I'm looking at, max draw is 6.5 amps at 100% duty cycle but less than 1.2 amps cycling.



is there any stats on how many Ah one of these fridges would draw over a 24 hour period? would be nice to see something say at a 40 degree cabnet temp in 90 degree weather parked in the sun it used so many Ah.

Steve


I have a small (4 cu ft) NovaKool with a Danfoss compressor. When the ambient temp is around 70 degrees or less it does a great job pull 2-3 amps with about a 1/3 duty cycle. That is about 20 or so AH per day. When the temps increase to the upper 80s or 90 degrees, the unit runs almost continuously. It keeps internal temp pretty well but chews up 60-75 AH per day. My solar system has 300 AH of AGM batteries so I am good for only 2 days in the shade or 2 days of clouds. Even with full summer sun my panels are not big enough to replenish the system with a full day of charging. Compressor refrigerators definitely have a downside.

StirCrazy
Moderator
Moderator
SidecarFlip wrote:
The one I'm looking at, max draw is 6.5 amps at 100% duty cycle but less than 1.2 amps cycling.



is there any stats on how many Ah one of these fridges would draw over a 24 hour period? would be nice to see something say at a 40 degree cabnet temp in 90 degree weather parked in the sun it used so many Ah.

Steve
2014 F350 6.7 Platinum
2016 Cougar 330RBK
1991 Slumberqueen WS100

Kayteg1
Explorer II
Explorer II
SidecarFlip wrote:
technology has made the old compressor fridges way more efficient. A standard fridge compressor is a power hog. The Waeco / Danfoss compressors aren't. Plus the Waeco / Danfoss units run on a duty cycle which means the compressor adjusts itself for ambient conditions whereas a conventional compressor runs flat out (high amperage draw) until the set temp is reached..


I've been repairing refrigerators as hobby and I know that about 20 years ago inverters come to the designs.
I actually had one of those $6000 household fridges, that somebody sold for the value of stainless steel on it, becouse inverter blow.
I spend like $150 on new inverter board and fridge worked again.
But IMHO in refrigeration inverter only adds cost and complexity.
Food doesn't care if the temperature fluctuate 2 or even 3 degrees, while inverter board become weak point in the design.
Had to be my luck that last year inveter board on my household washer blow as well? The replacement retails at $450 and spending time for net search I bought it only slightly cheaper.
Than this spring I was restoring Jacuzzi that I bought with house in Las Vegas. Guess what was wrong with it???? Electronic board, that become obsolete.
When in washer soft motor start has it advantages, I am not big fun on that technology.