Hi,

I found myself here after Googling my issue and coming across a thread which detailed a similar issue to mine - it was many years old but I'm hoping somebody can help me.

I have one of those mini fridges from Amazon that seem to be mass produced in China - it's not great build quality. It worked just fine for about six weeks then overnight it stop cooling.

• The fridge doesn't get cold
• The two (red and green) LEDs on the back no longer light up whether it's set to cool or heat
• The fan does spin up when it's set to cool mode so power is reaching it
• I tried connecting power via DC (ie bypassing the AC converter) and it still doesn't work

Is the switch the most likely candidate to have failed? It still clicks when I change position. It doesn't look like it's replaceable though.

I'm generally technically capable but not particularly experienced with electrical hardware. Looking at the inside of the fridge though it doesn't seem a very complex device so presumably failure points are limited.

Any suggestions / help would be amazing. I'm attaching a few photos to help show what I'm trying to describe.

 

This design is a little different than the typical wine cooler. (You can find a lot of info about those in this forum.) The problem with those is almost always the power supply, particularly one electrolytic capacitor called C8 in many of the schematics. My hunch for your problem is that the small control board has failed instead of the PSU. There's a remote chance you can find a replacement for that board.

It looks to me like the wires going to the module are the power, red and black, and the yellow wires go to a temperature sensor on or near the module. Can you check the voltage provided the module? It would also be useful to see what happens with the module disconnected. If it has failed to a short, it'll pull the supply voltage so low that the control board cannot function. You may have to desolder either the red or black wire to run that test.

You could also measure the resistance between the two yellow wires when turned off. The resistance there may change with temperature. If the resistance is not in the range of 1kΩ-50kΩ, it may have failed or is not a thermistor.

 

Thanks for the reply and apologies for me taking so long to respond.

Yeah, I'd looked at threads on this forum for other similar devices but like you say mine is slightly different.

The switchboard failing would have been my best guess.

I don't have a multimeter to hand but could probably lay my hands on one fairly soon. If and when I do I'll reply here with more info for the tests as you have suggested.

If the control board has failed do you think I would be able to switch it out for something different? Like a different kind of switch? Assuming the PSU is still functioning OK, that's doing the step down conversion to supply the Peltier module with a DC current, right? So the small board is just functioning as a switch?

 

If you have a multimeter, please check the voltage. I doubt that it is not sufficient.

 

• I tried connecting power via DC (ie bypassing the AC converter) and it still doesn't work

Tell us more about the 12V source and how you applied it. It would need to supply several amps and may have not been up to that chore. Desolder or cut the power to the TEC module and try again.

 

Tell us more about the 12V source and how you applied it. It would need to supply several amps and may have not been up to that chore. Desolder or cut the power to the TEC module and try again.

I used the DC cable that came with it - it attached to the lighter socket in my car.

 

I can certainly try again as you say.

I have a multimeter arriving today so will be able to investigate further.

 

I used the DC cable that came with it - it attached to the lighter socket in my car.

If it was powered and you didn't blow the fuse, then that should have provided enough current. Let's see what happens when you can collect voltage data.

 

I had a very similar AC/DC cooler, the fan ran but it didn’t cool.
In my case the failure was with the flimsy temperature reversal switch.
These large peltier assemblies draw like 5 amps, and the switch’s contacts had burned out.
But the only way to troubleshoot with certainty is with a DMM, good decision of yours to purchase one.