Rewire wine fridge to lower minimum temp

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Old 04-12-19, 09:18 PM
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Rewire wine fridge to lower minimum temp

Hey DIY, I recently acquired a wine fridge, unfortunately the minimum temperature is 7C (45F) and I'd like to use the fridge to keep food on occasion.

In the past I've rewired (dumb) chest freezers with electronics such as the STC-1000, however this machine is a little more complex. Is there any possibility I can adjust the minimum temperature? I'm happy to replace the temperature controller if need be.

Thanks





 
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Old 04-12-19, 09:29 PM
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Depending on the type of sensor a resistor in series might adjust the actual reading the board sees.
I assume the display shows the temp. I would try and find a number on the sensor and see if you can find any info on it.
Or you can measure the resistance and chill or warm it and see if it changes. Depending on the results you could them try putting a resistor in series and see if the temp goes up or down.
 
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Old 04-12-19, 10:05 PM
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Yes the display reads out current temp and displays the set temp when the temp is changed using the buttons.

Ok interesting, so you're suggesting a resistor on the temperature probe cable? It sounds like a process of trial and error with different resistances? I have a glass of water in there now to figure out what temp it actually reaches, ie how accurate the temp probes are.

From the diagram it looks like these 4 cables connect to the two temp probes.
 
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Old 04-13-19, 04:03 AM
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While you could play with sensor to adjust temperature offset, it probably is not a good way to adjuster temperature.
Those temperature sensors are not linear.

You are better off just bypassing existing controller like you did before on a chest freezer.
WH is what powers your compressor. Connecting BN to WH should turn on the compressor.

You could also use arduino and just replace existing controller chip and use the same circuit.
 
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Old 04-13-19, 05:20 AM
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You can not add a resistor to a thermistor cct to change it's operating range.
As said, you need to totally disconnect the unit's controller and use something in it's place.
We can not see the rest of the cooler to understand how it operates but you will likely have to set up some type of defrost system.
In order to operate at food preserving temperatures the evaporator coil has to operate at below freezing temps.
Also, the lower you set the temperature the more cooling power it takes so if you hack the controls you need to make sure it gets to a low enough temperature to keep your food safe.
 
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Old 04-13-19, 06:34 AM
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The wine cooler is manufactured with a design temp of 45 degrees. The size of the compressor, the condenser, the evap coil, and volume of refrigerant is engineered to produce 45 degrees. You will not be able to lower the design temp simply by modifying the control circuit.
 
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Old 04-13-19, 05:23 PM
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Thanks for the advice, I understand the cautions about overloading and evaporation. My goal is 2C lower than the current temp, so it shouldn't be pushing it too much.

I plan to use an STC-1000 I have on hand to connect BN to WH and engage the compressor and use one of the existing temp sensors. The bonus is I can connect the interior lightbulb to the heat side and have the fridge heat as well as cool.


I did a quick test and the unit seems happy, I've achieved my target of 4C. The temperature seems pretty stable throughout the interior however I might consider attaching a computer fan to the inside to help with circulation.

 
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Old 04-14-19, 06:01 AM
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Glad it worked out.
You can determine what % of capacity you are using when lowering temps by keeping track of the compressor running time.
You also should be able to fine tune the cycling of the compressor.
By lowering the design temperature setting you might find the compressor is cycling more often.
You would need to make sure the compressor stays off for at least 10 minutes or it may not have time enough for pressures to equalize making the compressor cycle on its overload protector.
You can maximize off time by setting a wider differential which you should be able to do with that control
 
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