Norcold Muddypaws mod

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Alpena Jeff

Alpena Jeff

Well-known member
Joined
Dec 7, 2014
Posts
965
Location
Up North - Michigan
I slipped some styrofoam between the thermistor and the fin.
Fridge currently under 15a shore power in my driveway.
I've had it powered up for 24 hours.
The temp setting is on 5.
Fridge is 34 degrees and freezer is 14 degrees. It looks like the fridge and freezer temps have stabilized.
Any idea how to get the freezer at or near zero?
Fridge and freezer are empty.
I have a 2 year old model 1210IMT
In the past I've needed to have the temp setting at 7 or 8 to get the fridge this cold.
I've never been happy with the freezer temp.
Thanks, Jeff
Outside temp is low 70's and cloudy.
 
I will say this.. I hear a lot of folks complaining how "Loud" the Air conditioners are

I keep my fans on all the time, mind quickly learns to tune 'em out and I actually have to LISTEN for them to hear them run.
 
John From Detroit said:
I will say this.. I hear a lot of folks complaining how "Loud" the Air conditioners are

I keep my fans on all the time, mind quickly learns to tune 'em out and I actually have to LISTEN for them to hear them run.
Click to expand...

Yo, John. I think you might have mixed your threads.  ??? We're talkin fridges here  ;)
 
My also two year old 1210 averages mid-high 30s with the freezer typically mid single digits (currently 36/9) - the coldest freezer temp I've seen was 5 I believe - I've seen the freezer drift into the teens. Running on propane, setting is 4. I too would like a colder freezer since as a fulltimer I may have food that's in there awhile. (I have remote thermometers so am not opening the doors to get these readings. I watch temps very closely and so also have non-remote thermometers, mercury and digital, to confirm that the remotes are accurate.) I keep the setting such that none of the thermometers hits freezing, but sits as close to it as possible.

I believe Muddypaws has reported freezer temps of -18F which is by far the coldest absorption temp I've ever heard reported, colder in fact by a few degrees than the last two freon cycle upright freezers I've owned. So I guess he got a good one.
 
First of all you should be loading both the fridge and freezer at least with several gallon jugs of water to buffer the temps of either, otherwise you'll chase your tail forever

Once thats done it makes a HUGE difference where you are looking at the temps: sensing on the shelf or up against the rear plate; there can easily be a 10 degree delta on that. I don't think any of these 1200?s will ever be the same. I changed to Helium but with the addition of my internal fridge fan and 4 extremely quiet Noctura fans on the exhaust vent controlled by my ARP and turning at 50%, with a full fridge and freezer I can maintain a fridge temp of 34, and freezer between -2 and -3 in temps anywhere from 65 to 115 as measured last summer. That on setting 5..  AFAIC, fans in the proper places make ALL the difference.

Also note that every two days the 1200 shuts down for 4 hours to do a defrost. Toy can cycle the fridge off and on before that happens, or get an ARP with the option that does this in the background and cancels that cycle.
 
I put 4 12v computer muffin fans on the output vent to suck air through the system.  They are controlled by a 180F thermostatic switch clipped to one of the fins.  That made a huge difference.  The box cools down and recovers roughly twice as fast.  I got most of the parts from eBay.

It's been working this way for a few years.  I had to adjust the position of the thermistor because it was too cold.  Currently it's at 35/-13 using my highly accurate 'El cheapo' thermometers and full of 'stuff'.  The real benchmark is rock hard ice cream and ice cold beverages. 
 
Has this thread been modified or started new in mid-stream.  I see that it refers to a mod on Norcold fridge and I have had problems with mine for a couple of years.  The basic problem has been that when I bought the coach in 2014, I could set the fridge at 5 and both freezer and fridge would be in the right range.  But since 2016 I have had to set it on 8 to get normal cooling/freezing.  I remembered somebody mentioning moving the sensor that is on the fins and I did that.  There was some gunk under it but it has not made much difference.  It does seem to  have been exceptionally hot the past couple of summers so maybe that is the problem.  Anyway, I would like to know some of the fixes people are trying to alleviate this type problem.  Thanks.

Bill
 
Moving the thermistor is not intuitive.  As adjustments go the centermost position on the fin will make the box warmer.  The further you move it out from the center (vertically) the colder.

If you set your rig up so that the refer side gets afternoon sun it will be warmer in the box.  But since nobody wants hot afternoon sun on their 'patio' that's the way it usually works out.  Even my refer gets warmer in the hot afternoon sun.  Sometimes even bumping on 39F.

My observation, based on several Norcold 1200 series refers is that setting the control panel to any value higher than 4 does nothing.  It may actually make the box warmer.

This is the thread I started 4 years ago.  I had been having success with the mod for over a year at that point.  http://www.rvforum.net/SMF_forum/index.php/topic,77620.msg704239.html#msg704239

 
The temperature sensing thermistor is in the fridge compartment. When it gets down to the set temperature, cooling will stop, regardlwss of what the temperature is in the freezer compartment. There are only two ways to make the freezer cooler.

The first way is to cool the refrigerator even more. That will make the freezer cooler, but will have the undesirable side effect of freezing everything in the refrigerator.

I have the same problem, and I found a solution. Connect two 8 ohm, power resistors in series, connect the pair of them to your 12 volt supply, and throe them into the refrigerator. At 12.5 volts, they will dissipate about 10 watts, which will be just enough heat to keep the refrigerator from freezing, while causing it to run with a higher duty cycle, thus causing the freezer to get colder.

This resistor https://www.radioshack.com/products/radioshack-8-ohm-non-inductive-resistor should work, but you may need to adjust the effect. A larger resistor will add less heat, while a smaller one will add more. you an find them at https://www.digikey.com/products/en/resistors/through-hole-resistors/53?k=Power%20Resistors.

Joel
 
Great Horned Owl said:
I have the same problem, and I found a solution. Connect two 8 ohm, power resistors in series, connect the pair of them to your 12 volt supply, and throe them into the refrigerator. At 12.5 volts, they will dissipate about 10 watts, which will be just enough heat to keep the refrigerator from freezing, while causing it to run with a higher duty cycle, thus causing the freezer to get colder.

This resistor https://www.radioshack.com/products/radioshack-8-ohm-non-inductive-resistor should work, but you may need to adjust the effect. A larger resistor will add less heat, while a smaller one will add more. you an find them at https://www.digikey.com/products/en/resistors/through-hole-resistors/53?k=Power%20Resistors.
Click to expand...

If you want to add heat in the refrigerator compartment, just jumper the door switch so the interior light is on all the time.  It'll produce about the same amount of heat as the resistor.
 
I got this for mine and love it.  Unlike a household or commercial refrigerator, the RV units are "still air" and have very uneven cooling inside.  This little fan setup really helps!
https://www.ebay.com/itm/Dometic-Refrigerator-Deluxe-Fan-to-INCREASE-cooling-inside-with-METAL-GRILL-/181208057633
 
Lou Schneider said:
If you want to add heat in the refrigerator compartment, just jumper the door switch so the interior light is on all the time.  It'll produce about the same amount of heat as the resistor.
Click to expand...
Hey Lou. How do you jumper the door switch?
 
Because my fan blows across the entire aluminum fin assembly, I have a clockwise circulation in the entire fridge.. Everything is the same temperature, and in MY case it makes no difference where my thermistor is at, because the temp is the same across the entire assembly: left to right, top to bottom... It shuts off when the BOX temp is where it belongs, not just that one fin. Thats also why I dislike that pair of fans on the plate shown above.. They are trying to make 4 fins in the fridge work to cool everything down instead of the entire assembly.. That makes no sense, and it doesn't solve the problem of moving air around in the box. Mine does it all in one-fell-swoop.
 
To circle back to OP?s original question, assuming the fridge maintains a mid 30s temp on a mid setting, there isn?t anything that can be done to make the freezer colder (aside from making the fridge too cold), correct?  ???
 
8Muddypaws said:
Moving the thermistor is not intuitive.  As adjustments go the centermost position on the fin will make the box warmer.  The further you move it out from the center (vertically) the colder.

If you set your rig up so that the refer side gets afternoon sun it will be warmer in the box.  But since nobody wants hot afternoon sun on their 'patio' that's the way it usually works out.  Even my refer gets warmer in the hot afternoon sun.  Sometimes even bumping on 39F.

My observation, based on several Norcold 1200 series refers is that setting the control panel to any value higher than 4 does nothing.  It may actually make the box warmer.

This is the thread I started 4 years ago.  I had been having success with the mod for over a year at that point.  http://www.rvforum.net/SMF_forum/index.php/topic,77620.msg704239.html#msg704239
Click to expand...
Where did you mount the computer fans?  Are they controlled by a switch?  Moving the thermistor on the fin (vertically) - is higher or lower the preferred position to achieve more cooling?  Sorry to sound like a dummy but it looks like you have solved the problem.  Frankly I don't care what the freezer temp is(as long as it is freezing)  but the fridge is needing to be at least on #8 at the present - haven't yet tried it this season.  Thanks for the info.

Bill
 
We're on the road today.  When we settle in to our new spot I'll fire up the laptop and see if I can find the pictures etc.
 
Sun2Retire said:
To circle back to OP?s original question, assuming the fridge maintains a mid 30s temp on a mid setting, there isn?t anything that can be done to make the freezer colder (aside from making the fridge too cold), correct?  ???
Click to expand...
Questions:
Where are you measuring both of your temps?
Is it with or without food, or at least test water jugs in the boxes?
Is there a circulation fan in the fridge box?
Exhaust fans other than the OEM from NORCOLD?
-is this on LP, AC, or both?
-if LP, when was the last time you removed the burner?

Each one of the above have made a difference in how ours performs, or how it?s preceived to be performing. 36/9 is high to me, but it?s entirely possible that the unit is hitting its set temp and shutting off not knowing it has additional heat to shed.
 
Heli_av8tor said:
SCVJeff, Could you provide some details on your circulation fan in the fridge box?

Thanks, Tom
Click to expand...
only if you tell me how you arrived at that handle.. :)
I used an 80mm Noctra fan mounted directly behind the light, blowing left to right. Its mounted with a small piece of VHB tape. I?d post a picture, but the process here is so convoluted trying to do it on an ipad, I?ve given up. Ill email you pick if you want to look?
 
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