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Fridge Fans (Internal & External)

Anyone who uses an absorption refrigerator, like our old Dometic NDR1292, knows that the hotter the weather, the less efficient these fridges operate. Basically, it gets increasingly difficult to get hard ice cream as the outside temperature rises.

Adding a fan (inside or outside a fridge) is a relatively inexpensive method of improving the performance of an absorption refrigerator.

INSIDE A FRIDGE

The purpose of adding a fan inside a refrigerator is to improve efficiency by moving the cool air around.

Fridge_Fans_09

12V Internal Fan

I tried a 12V internal fan that I bought on eBay. This 2-fan unit draws its power from the light inside the fridge. Don’t worry, it’s connected in such as way that the fan stays on when the door closes.

This virtually silent dual-fan moves the air around pretty well.

Battery-Powered Fan

Battery-Powered Fan

Another type of internal fan just uses a battery to power its fan. These units run for a long time, but must be constantly monitored. Camping World sells them as well as other vendors.

However, while both of these internal fans worked ok, I had heard that adding an external fan to cool the refrigerator itself might work a lot better.

OUTSIDE A FRIDGE

The goal of an external fan is to cool the gas absorption unit of the refrigerator itself.

On the back of an absorption refrigerator — the business side — a cooling unit is attached to the back of the fridge.  The cooling unit works by heating a tank of ammonia which turns from a gas to a liquid. This process cools the refrigerator, but heat is generated which is supposed to be removed by the convection air flow in the back of the fridge.

Fridge_Air_Flow

However, in hot weather it becomes more and more difficult for convection alone to remove this heat.

So to improve air flow a fan can be placed either at the back of the cooling unit or at the roof vent. I added two thermally-controlled fans from www.coolerguys.com inside the roof vent. These fans turn on when the temperature reaches 88 degrees F.

Here are photos from my installation . . .

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11 Comments Post a comment
  1. Rick Merritt #

    I am curious as to your results with this vent fan. It is something I am thinking about doing for my Norcold. Did you document any temperature change results? Interesting that you would take up the whole vent unit – I was just going to pull up the critter screen and make a bracket to hold the fans and then put the screen back down. Your method looks cleaner.

    December 13, 2013
    • I didn’t log my temps. I just kept checking to see if the fridge temp was less than 40 degrees. It didn’t. The hot weather got the best of it. What worked the best for my Dometic was the addition of the adjustable thermistor — which in essence just tricks the fridge into thinking it’s warmer so it starts cooling more. However, I’m not sure if you can use an adjustable thermistor on a Norcold. Check http://www.dinosaurelectronics.com

      December 13, 2013
  2. Rick Merritt #

    Thanks. That is disappointing that the fans didn’t help. So maybe I will put that project on hold. I tried dinosaur for a thermistor but they don’t make them for my Norcold since it has an adjustable thermostat. The other option is a residential frig but we boondock and I like the propane option. Thanks again.

    December 13, 2013
  3. van der klugt j #

    we reside in australia looking for a 12vlt internal fan already have 2 external fans
    any assistance would be appreciated
    self/retired/volunteer

    December 27, 2013
  4. van der klugt j #

    many thanlk’s

    December 27, 2013
  5. Douglas Smith #

    Do you have a drawing of the wiring from the fan to light

    August 31, 2014
    • No. I suggest you get a voltmeter so you can locate + and – 12V in the switch.

      August 31, 2014
  6. Tosin #

    I just bought my haire thermocool refrigerator and it gets hot at the sides…can the external cooling fan supress the hotness on the sides?

    April 25, 2016
  7. Ed Logan #

    Well, I got the two fan fridge cooling unit, and have it mounted to the cooling fins (that’s the ground) in the Norcold N-811. However, there’s no hot wire in the light when the door is closed… a magnetic switch in the door frame kills the power to the light when when the door is closed. I guess that it’s a senior moment… I just wasted the money on the fan!

    July 20, 2016

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