How to turn up the bar fridge?

Discussion in 'The Projects Forum' started by Dalaran, Apr 22, 2011.

  1. Dalaran

    Thread Starter Active Member

    Dec 3, 2009
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    I have a bar fridge (well actually a wine cooler) which doesn't get quite as cold as I would like it with the temperature setting maxed out.

    I have attached a picture of the thermostat with model #: WDF12B-L, but I can't seem to find much information on it. There are 4 wires connected to it, 1 red, 1 black, 1 green and 1 bare. The green is the ground connected to the metal case. The bare wire goes into the fridge and I believe measures the temperature. And then the black and red I would guess are shorted to turn on the compressor when the temperature is high, and then disconnected when the temperature is low. Is my understanding correct?

    So how would I go about increasing the temperature range of this thermostat? I've though of setting up something to bypass it and turn the compressor on for a period of time but I'd like to just be able to adjust the range of the knob down a few degrees.

    Any thoughts are appreciated.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Can you get at the probe inside the fridge? Changing the temp that it "sees" - by maybe taping it to a sidewall or otherwise isolating it slightly - might be the easiest way to keep the compressor running longer.
     
  3. Dalaran

    Thread Starter Active Member

    Dec 3, 2009
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    Unfortunately I can't get to the probe on the inside without doing some hacking.

    Thanks for the response though.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Hmmm... I think your options are limited, short of adding a completely different thermostat system. I don't think there's much you can do to modify the existing thermostat, although it's a bit hard to tell what sort of probe it is. The tube going to the probe is, I think, filled with fluid? Can you tell?
     
  5. debe

    Well-Known Member

    Sep 21, 2010
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    That (bare wire) is actualy a capilary tube with liquid in it & sealed & conected to bellows in the thermostat to operate the contacts. Not realy a thermostat that can be altered easily. Mechanical thermostats are each designed for particular temp ranges. You need an electronic thermostat, mutch easier to alter.
     
  6. Dalaran

    Thread Starter Active Member

    Dec 3, 2009
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    Thanks for the feedback. Doesn't sound like I will be able to do too much to it.

    Am I correct when I say the red and black wires are shorted to turn on the compressor?
     
  7. debe

    Well-Known Member

    Sep 21, 2010
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    Thats corect. Heres a circuit i used to controll a fridge.
     
  8. Dalaran

    Thread Starter Active Member

    Dec 3, 2009
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    Cheers. Thanks.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    That's a nice drawing - complete for this task. A similar-in-operation circuit is here, without the fridge details.

    Point is, use the LM35 sensor and compare its output to a reference. Throw a relay based on that comparison.
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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  11. Wendy

    Moderator

    Mar 24, 2008
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    Wonder if a resistor next to the sensor would help. It would heat the sensor, and the fridge would have to say on longer to compensate. Definitely a kludge.
     
  12. debe

    Well-Known Member

    Sep 21, 2010
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    This is pics of the electronic thermostat imade for my fridge. Circuit posted earlier.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Well, it looks like a thermistor is being used for the temp sensor, it may be as easy as changing it to a different value.

    Less than $1 each at Mouser.
     
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