Mistakes and mods and keeping my fridge cool (Update 6/5/19)

ChrisK

We have the Norcold 3-way fridge. On our last camping trip, we ran it on propane and the cooling was terrible. We basically threw away some food because it got too warm. I figured the fridge was going bad. We had never had problems with the fridge. It always cooled enough to freeze food if we didn't turn it down. 
I got home and went into sleuth mode. Was the fridge bad or was something else amiss? I fired up the fridge too see how cool it would go. With an outside air temp of about 95, it would only cool to 65. At night with the temps about 80, it would drop in to the 50s. That was bad. I started with the first thing which was to make sure the internal cooling fan was working. It was. After reading several articles on here, I had NuCamp send me the vent fan upgrade. I installed it and could now cool down to the high 40s. Still not good enough for meat. I designed and 3D printed a dual fan bracket for the internal fan. I got the fan installed and tested it to find flow direction. Airflow should be from the bottom of the coils up through the cooling fins in the fridge. Wait a minute, the flow was going down! Yup, I installed it upside-down! I had no cooling to the upper cooling fins. No wonder it wasn't cooling properly. I switched them around and can now, I can maintain temps in the 30s even on a 90 degree day. All of the above temps were with the inside of the camper at outside ambient temp. 

Learn from my mistake and make sure if you replace the internal fridge fan that it is flowing the correct direction.

Vent fan installed.


Dual fan setup. (Edit - this was actually with the fans oriented properly after I fixed it)


Also did a variation of Dale's front vent. My printer only goes so wide so I elected to put it down low where the coils are and to give the fans somewhere to pull from.

jgram2

Cool!

ericnliz

In T@B lingo...T@D@!!!!!!

PJ123

Howdy All from southern Louisiana!! Nice job on the side vent but did I see a screen in the background of the first pic?  We too have had cooling problems with our NC three way cooler.  It would cool to a certain point then shut down.  Wait awhile and it would again cool to a certain point then shut down.  When it would cool it would never get as cool as it should. The counter  by the outside wall next to the stove was very hot also.

  We realized that the only difference in the scheme of things was that DW had installed nylon window screen in the vents since the last trip in an attempt to keep the wasps and other crawlies from nesting behind the fridge.

   Low and behold, we removed the screen and cooling problem went away.  It seems that even tho the screen was passing air thru it was just enough of a barrier to hold back a LOT of the heat from the fridge to the outside. 

  As y'all know there are grates that can be installed in the icebox vent to outside openings as well as larger mesh metal screen.  I suppose that's the way we're going to have to go to take care of the wasp problem.  In short, as long as there is unrestricted air flow to and from the outside vents our fridge nails it just like new.    

  

ChrisK

Mine cools pretty well now. I'm probably going to add a second fan to the grill opening as insurance just in case. I'll wire it to its own switch so I can select either one or two fans.

gbell

@Chrisk could you share the 3d pattern used for the screen. Our library has a 3d printer that maybe I can use to make one.  I always thought it needed more air. Sometimes the frig is great, sometimes not so great.thx

ChrisK

@gbell I tried but it won't let me attach them. Send me a private message with your email and I'll send them to you.

ColleenD2

@PJ123, I wonder if there is any benefit to making some kind of temporary cover for those side vents when the unit is not in use, kind of like the AC covers. Maybe just a magnetic sheet? I’ll have to think about this, been seeing a lot of wasp comments.

jkjenn

Maybe 2 smaller grills would have worked better. This seems worth doing. Might be a winter project for me.

ChrisK

jkjenn said:

Maybe 2 smaller grills would have worked better. This seems worth doing. Might be a winter project for me.

I drew up a smaller vent thinking I might want to do one at the top and one at the bottom but settled on this one. 

ChrisK

OK, last mod for the fridge (maybe).
I've been kind of obsessed with getting my fridge to cool as much as possible so I can have some buffer.
The 3-way fridge in these requires two things to get cold. It needs heat for the lower coils and cooling of the condenser (the finned thing on top). Heat to the coils is the easy part if your fridge is working correctly. The more critical part is keeping the condenser cool from what I've read. Prior to this experiment, I was able to keep the fridge in the 30s up to about a 90 degree day. I was just putting the fridge and stove top back together from the above mods and saw the base of my 3D printed fan sitting on the counter. The base contains a 50mm fan. I decided to lay the fan on the fridge top with the fan oriented such that it was pulling air from the condenser fins. I closed everything back up and let it run. With that running constantly, I was able to get the fridge down to 30 with the evening low around 85 and around 45 during the heat of the day (over 100 degrees). I don't think the other 2 fans ran much if at all. With that result I ordered another of the quiet 80mm and and created and printed a mount for it. I installed it with a 3 way switch so I could turn it off completely, run it on the thermostatically controlled fan switch with the other 2 fans, or have it on constantly in case of a failure of the fridge thermostatic switch. With everything installed, I tested again last night and today. The fridge got down to 29 with an outside low temp of 85 and 39 with the outside temp of 103. That's pretty good considering the inside of the camper was at ambient. It should work better with the interior cooled off. Plus, if its 103 at the campground, we won't be camping there. I only plan on running the 3rd fan on hotter days as the 2 other cooling fans seem to do just fine on their own and to help cool the fridge down prior to loading it up to go camping. Before all this, the fridge was not very cool for loading everything up and we relied on the temps of the stuff we were putting in it to help cool it. 

Final fan count. 1 vent fan. 2 fans above the coils. 1 fan above the condenser. For boon docking, I can drop that down to just 2 running if I need to save power.

Anyways, on to the pics.....

Here's the 3rd fan installed. The mount was designed to clear the stovetop when it is in place.


Here's its switch. 3 position. Thermostat-Off-On. Its in the thermostat position here.

ChrisK

And before anyone says anything, yes, this was a lot of work and I could have just bought a portable cooler like a Yeti. The difference is I don't have to lug something extra around and this only cost me maybe $25. Plus, I like to find solutions to problems so this was fun for me. 

ChrisK

Update with real world testing.
We're one week in on a two week camping trip. Outside temps have been from 37 degrees at night to 95 degrees during the day.

On the whole, I'm real happy with the results. I could keep the fridge at or below 40 while traveling on 12v with outside temps up to 95 degrees. On 110v, I typically would set the power control knob to only 1/4 to maintain about 40 degrees. At night, I usually turned the 3rd thermostatically controlled fan off.

I didn't get a chance to test it on propane. 

I'm pretty happy with the results. I don't worry now about my fridge even with higher outside temps. I love having the fridge temp sensors so I can monitor the exact temps inside the fridge. No guessing that the temp was good. I did find that for such a small space, the temps inside can vary from side to side (the fridge temp gauge has two sensors). Before the trip, I did create an internal fan to move the air around but decided not to bring it. I wanted to test the fridge as it was with just the current fan additions. My next camping trip I'll bring the internal fan too to see if I can more even temps inside the fridge.

Michigan_Mike

Must be nice to have a 3D printer!!!!  

Good stuff, great write-up and thanks for taking the time to share your tedious work and experiment as this is something that comes up quite frequently and will help others out down the road.  I believe that 37° F is about the ideal median temperature for keeping things fresh and edible in a refrigerator and I had the same, frustrating problem with my former 3-way in my 320.  

Sharon_is_SAM

@ChrisK, do you think this would help a 2 way frig?

ChrisK

Sharon_is_SAM said:

@ChrisK, do you think this would help a 2 way frig?

It should help any absorption style RV fridge. Cooling the condenser fins is the key to keeping these fridges cool. 

duckblind123

I have experienced the same lack of cooling issue, but it is only recent development.  Prior to this, we could not have the cooling setting all the way up or the fridge would begin freezing food.  Now, we can put it on high and the fridge only gets to around mid/low 40's.  The outside temp is up there as well (mid 90's to low 100s), but that did not cause issues before.  So, I did some basic troubleshooting and wanted to find out if others could assist me further.  The below is running on the T@B on battery power only:
   1st - I have confirmed that the external vent fan (the one mounted to the outside of the T@B) runs/is running, when I turn the fan power switch on.

   2nd - I have confirmed that when I rotate the 3-way power switch to battery power, the internal fan (the fan located on the left side of the fridge that blows air up through the fins/coils) does not come on/blow air.

Question: Is the fan located on the left side that blows air up through the coils/fins supposed to begin running as soon as power is applied to the fridge?
-OR-
   Is this a temperature sensor fan that only runs when the temp reaches a specific level?

Reason I ask is that in troubleshooting, I did not let the fridge run very long (not long enough for the temp to rise very high).  I have not checked the voltage to the fan to see if it is getting power and the fan is bad or if I have a power/wiring issue.  Thoughts and suggestions welcome!
Regards,
Marc Woolverton
Winchester, VA
2016 T@B Max S

ChrisK

The left side fan only runs when the thermostat tells it to. It is the most critical fan for getting the fridge to cool. If your fridge is not cooling well when it used to, it could be the thermostat or the fan itself. To test, see if the fan comes on. If it does not, you’ll want to see if power is getting to it from the thermostat switch. If it isn’t, you also need to see if power is getting to the thermostat switch. Follow the diagram on the fridge top to find where the power stops. 

duckblind123

Thanks. I will continue further troubleshooting efforts.  Thanks for the additional information.

ChrisK

As a reference point, it is 97 in Moab today. We had all 4 (3 fridge on thermostat switch, 1 vent) fans running. I had turned the fan up to about 1/3 power before we left for Arches National Park. We got back and the fridge temp averaged out to 34. I turned it back down to 1/4.

duckblind123

I just wanted to provide an update on my fan issue for my Norcold 3-way fridge.  My primary issue was the fridge was not cooling.  After investigation, it appears the fan that is supposed to blow across the fins was not turning.  After checking voltages and fuses, I thought the issue was the thermostat.  I contacted Norcold and they advised that the thermostat was set to "turn on" at 85F degrees.  I used a hair dryer to ensure the temp was high enough on the thermostat.  After confirming with a meter that the thermostat did in fact "engage" and make the connection, the fan was still not coming on.  I had a 12v battery from an old alarm system and used it to connect directly to the fan and confirmed that the fan did work.  So, that left me with the connections from the fan (one to the thermostat (positive) and the other to a negative lead).  I replaced (one at a time) the positive and negative connectors coming from the fan and checked to see if the fan would engage by raising the temp of the thermostat with the hair dryer.  The positive had the same issue, but it appears that the negative was the culprit.  After replacing the negative connector and using the hair dryer to raise the temp, the fan kicked on just as it is designed.  Anyway, if you are having the same issues of the fan not coming on, check all fuses, but then conduct the voltage checks until you can isolate where the voltage is NOT present.  Just wanted to provide this info if anyone else was running into the same issue.

Sharon_is_SAM

Good info.  Is your frig cooling now after the fan fix?

duckblind123

Yes, the outside temp this morning was 56 degrees F.  The fridge setting was all the way up on cold.  The inside fridge thermometer was reading 5 degrees F.  Best yet, there was no heat on the counter above.  When the fan was not working, the counter got really hot (not just warm). So, the fan is working again and it is cooling down the fridge as designed.

ChrisK

Good to see you figured it out. As my tests have shown, the fans are the most important thing to keeping the fridge working properly. 
My 4 fan setup works incredibly well. I plugged in the camper and turned the fridge on to pre-cool it for camping this weekend. The temp is 70 ambient out with an overcast sky. Within one hour, with all 4 fans running, the fridge has already cooled down to 44 degrees. I turned off the 3rd cooling fan but left on the vent fan. I also turned dow the thermostat.
I think the 3rd coil cooling fan will only be needed on days over 90 degrees. I don't usually camp on days that hot but it regularly exceeds that on pre-cooling days.

ChrisK

Just wanted to post an update. Today, it was 100 degrees out. We are leaving tomorrow for a long weekend so I turned on the fridge at 11am. All 4 fans were running. By 5pm, the fridge was below 40 degrees. 

AldebaranJill

Is it possible to wire the left fan to cone on anytime the fridge is on (and not only when thermostat tells it to?)

ChrisK

@AldebaranJill My top left fan has a 3 way switch. Center is extra fan off. Forward is extra fan on with thermostat. Rearward is extra fan on. I can't remember how it is wired but I think it was to a 12v source that was only on when the fridge is on. Maybe I connected it to the 12v source wire that feeds the thermostat sensor? Its been a while. You could hook any of the fans like that.

AldebaranJill

@ChrisK And do you have a link to purchase a quieter fan that would be drop in replacement for original fan below fins?

ChrisK

AldebaranJill said:

@ChrisK And do you have a link to purchase a quieter fan that would be drop in replacement for original fan below fins?

It's been so long since I did this and I've bought so many fans for various projects, I couldn't be sure which size it was. The brand was Noctua.