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.

 

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.

 

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.

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

Thanks for the response though.

 

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?

 

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.

 

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?

 

Thats corect. Heres a circuit i used to controll a fridge.

 

Cheers. Thanks.

 

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.

 

Most people use these to control wine coolers and other temp applications, you can often find them for less than $50 (or possibly even less on eBay)
http://www.amazon.com/Johnson-Controls-A419ABC-1C-Electronic-Controller/dp/B0026NDC5O

They're available to be powered by either 120VAC or 24VAC and the output is a totally isolated SPDT relay.

 

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.

 

This is pics of the electronic thermostat imade for my fridge. Circuit posted earlier.

 

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.