Fixing a Thermoelectric Wine Fridge

I recently got a small wine fridge that holds about 10 bottles, previously recycled by someone else due to it not working. Many wine fridges today seem to use a thermoelectric (Peltier) cooler, and while I like the technology due to the lack of moving parts, they are inefficient compared to its compressor counterpart. Still, free is free and I set about figuring out what is wrong with it. The obvious test of plugging it in and feeling for cool air told me it wasn't cooling down.

As I mentioned, thermoelectric cooling is quite simple in design: you have what is basically a large chip where one side gets hot and the other side gets cold. If you want to know the details of how they work you can visit our selection guide on thermoelectric coolers.

The diagnosis

I opened up the back of the machine and saw a circuit board and a large heat sink with a fan. My first test was to determine if the problem was in the circuit board, which is really just a power supply and thermostat. Most thermoelectric devices in this size range use about 12 volts DC to power them, so if I was seeing about 12v DC going to the cooler, then the circuit board was likely good. I followed the wires going to the cooling chip and measured the voltage across them with the device powered on. My meter registered 12.45v DC, which told me the board was likely working. This really only leaves one part that could be bad-the thermoelectric cooling chip itself. This is where thermoelectric cooling both shines and fails, because the chips are small and cheap and not too difficult to replace. At the same time, I find the failure rate for them is higher than a traditional compressor system. I would imagine the cost of them is one of the driving factors for using them in these small fridges.

The fix

The thermoelectric cooler is sandwiched between two large heat sinks, with the smaller one that gets cold being inside the fridge and the larger one that gets hot being outside. After removing a fan and some screws that hold the two sides together I could see the cooling chip. As a quick test to confirm my suspicion I held the chip in my hand and briefly powered on the device. Not surprisingly, nothing happened in terms of a temperature change.

The cooler used in this device was marked TEC1-12706 and a search turns these up for sale in many places for around $4 shipped. As luck would have it, I had some thermoelectric coolers on hand that I had purchased from a surplus store for a previous project for cooling a CCD. One of the ones I had matched in size and close enough in wattage.

Installing it is really just the reverse of taking out the old one, except I cut the wires off the old one and soldered the new wires to it. I also used some thermal grease compound on the cooler as it helps with the heat transfer.

The reward

Once everything was wired up I plugged in the fridge and felt the cold and hot side of the heat sinks; within a few seconds it was obviously working. I reassembled everything else and put the back cover on, plugged it in, and let it cool down. Now all that is left to do is fill it with wine, drink it, and repeat.