Author Topic: Tweaking the thermostat on a mini fridge, no external controller needed!  (Read 31637 times)

Offline kkey

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I haven't seen anyone mention something like this before, so i'll post this since it might save a few of you from buying the Johnson controller when you need not:

I just bought a $25 mini fridge from a student at the local university where I work (students have to move out of the dorms for summer, so there's plenty of good deals on craigslist right now).  Its Sanyo model A2480m and only 1 year old. On its lowest setting (1) it only gets up to 40F.  I wasn't happy at the thought of spending double that on an external Johnson controller; just didn't seem right in a volumetric sense of value.  I did notice that the thermostat in the upper right of the fridge was rather large looking. Hmmm, decided to unscrew the cover (after unplugging the power cord) and found inside it the Chuzuo Phoenix Automatic Controller TD-004-P2102 with a few wires sticking out, plus in the middle was a thermocouple (a metal tube that looks larger than wires, in the photos below you can see it is the one with the white plastic cover). Ends up that there's a calibration screw on the top of the controller, right in the middle near where the thermocouple comes in.   I tried to google the controller in hopes of finding a spec sheet, but no luck.  I decided to loosen the screw and see what happens.  An hour later I see the fridge now goes to 42F.  Over the next few days I fine tuned it and now it stays in the 52-55 range, just perfect! There's another screw on the bottom of the unit but i'm not sure what that does.

So, a $25 mini fridge, no external controller needed.   Don't know if every mini fridge is this easy, but its worth checking.  Just remember to unplug the power cord before you start opening it up, otherwise those wires on the thermostat controller have 110V!  Below are some photos.  The calibration screw is visible in the second photo, to the left of the black wire.

 
« Last Edit: June 04, 2011, 06:59:08 PM by kkey »

Offline MrsKK

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Way to go!  I bought a mini fridge that doesn't have a freezer compartment in it and was thrilled when it "cooled" to 58* F at the lowest setting.  I'm easily able to keep mine at 52-55.

Hopefully, your tinkering around will help others out here.  $25 is a HUGE bargain for a cheese cave.

Offline kkey

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Thanks, i'm pretty happy with it so far, although i'm sorta missing the "hassle" of my old cave (large beach cooler), which absolutely required  visits twice a day with a fresh ice pack.   

Also, for what its worth since you can't always believe the online reviews:

 I spent a bit of time reading  amazon.com reviews on the various mini fridge brands (magic chef, igloo, black and decker, etc).  Sanyo models have consistently high reviews, whereas many of the others have alarmingly negative reviews about poor quality.   

Offline zenith1

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very nice work!
Keith

Offline Gürkan Yeniçeri

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Good work KKey. Now on to the humidity!  ;)

Offline steffb503

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Yes some one mechanically inclined really needs to come up with the proper unit for cheese aging.
Think of the money to be made.

Offline pliezar (Ian)

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Here is a cautionary tale of doing this.

Reading the instructions someone posts very carefully is very important and is something I did not.  I took out my Thermostat to make an adjustment and could not find the adjustment screw on the top.  I said to my self...self lets look at this screw on the bottom. I have to stop listening to my little voices, but anyway I tried the screw at the bottom and it fell out.  I thought I had put it back in but it was not.  My Fridge turned into a freezer, cheese was saved before this happened.

The screw on the bottom connects to a spring that moves a plate inside the thermostat that turns the fridge off.  Mine would not turn off.  I ended up pulling the whole thermostat including the probe out of the fridge.  I had to take the thermostat apart and reconnect the screw to the spring that attaches to the plate.  I then put it back together and when I went to put it back in the fridge and hook everything back up, the probe snapped off the thermostat.

I now have to send $12 to the manufacturer and they will mail a replacement thermostat to me, well they will when I send the money after the postal strike ends in Canada.

I have been using my fridge like a cooler, using ice to maintain the temperature.  I have a new wine fridge that I am using now too(early father's day gift), but I will get the part for the old fridge.

Let my stupidity be a tool for learning.  Oh  I found the adjustment screw, it was covered.

Offline kkey

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Bummer but sounds like you'll be able to recover since you now know where calibration screw is.  This would so much easier if we could find the spec sheets for the thermostats online.    Anyone have any connections with electronic component manufacturers in China?

Offline Gürkan Yeniçeri

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My neighbour was throwing away an old bar fridge and I took over (my wife wasn't happy) and removed the thermostat carefully, attached my trusty digital thermometer and unscrewed the adjustment screw a little. It went down to -1C. Then I screw it back in as much as I can, this time it sits at around 9 degrees celcius. I gues the thermostat can only control this much.

If someone posts a link to thermostat spec sheets I might replace mine with another which can control up to 17C or so.

Pliezar, everything we do is a learning process. It's just never ending.  ;D

Offline steffb503

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Kkey,
I have a question on this. Do you know how far you can go with that screw?
Can it fall out? I have done like you did but I am at 46F and afraid to go further.

Offline eatfruit

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Re: Tweaking the thermostat on a mini fridge, no external controller needed!
« Reply #10 on: August 02, 2011, 11:00:13 PM »
I just bought a mini fridge and followed your instructions, despite the cautionary tale I unscrewed the wrong one first, but it screwed back in fine and now I am waiting to adjust what I think is the correct screw to the right temperature. I also unscrewed the calibration screw until it fell out but it screwed back in no problems and is working to turn the fridge compressor on/off, so fingers crossed I didn't damage anything. I hope that I can get the temperature up to an acceptable level. I did a cheese making course on the weekend and I can't wait to make my first Camembert! Thanks for the info, and the photos, it gave me the confidence to give it a go!
I will let you know how it works out.

Offline Fatman

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Re: Tweaking the thermostat on a mini fridge, no external controller needed!
« Reply #11 on: August 02, 2011, 11:12:23 PM »
I have found the small wine fridges work without tinkering they actually will adjust to 55.
Home Depot sells a very nice one with a digital thermostat..
Peeeyewww!, hmm wait a sec I bet thats some good cheese.

Offline kkey

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Re: Tweaking the thermostat on a mini fridge, no external controller needed!
« Reply #12 on: August 05, 2011, 11:50:33 PM »
Want to post a follow up to my mini-fridge experience. Its still running well at 50-55F, but i've found that the cooling mechanism (the metal ice tray area at the top) sucks the moisture out of the air every time it cycles on (and the ice tray cools to freezing temp), so it dries the air out and all the moisture collects in the drip tray below the ice region.  I have to empty that every few days or else it overflow. With a few bowls of water at the bottom I can get it to 70%RH, but that's about it.  I've made several good soft cheeses (Crottin de Francois and Chaource) and have a few tommes waiting it out for the long haul. So far so good.

Offline steffb503

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Re: Tweaking the thermostat on a mini fridge, no external controller needed!
« Reply #13 on: August 06, 2011, 05:28:58 AM »
I have a few of those wine coolers and although they say they go down to 55 or 50 mine usually end up around 54 for the cooler one and 57 for the other, two different companies.
And they are small. By getting a fridge without a freezer i have a full 10 cubic feet of cheese cave. Also with no freezer there is less abuse on the compressor.

Offline John (CH)

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Re: Tweaking the thermostat on a mini fridge, no external controller needed!
« Reply #14 on: August 06, 2011, 06:08:36 AM »
kkey thanks for the thread, looks like we have the same mini-fridge to use as a cave, I also took mine apart but didn't find that screw adjustment, and thus bought another external thermostat. Will have another go!

I also have the same problem of cyclic freezing of freezer coils, and in thaw cycle condensation dripping onto drip tray which if I don't mop up with cloth eventually builds up and overflows into fridge area below. I have not found a way around that.