Thermostat Bypass/Replacement?

I recently picked up a 6 cu. ft. beverage cooler for a steal, and I plan on using as a kegerator. But I have recently been having trouble keeping temp (surprised?).

The internal thermostat is digital/automatic and won't allow you to set it below 39degF. I wouldn't have an issue with having it at 39, since that is how cold I usually like beer, but once it hits 39 the compressor shuts off and doesn't come back on until 47-50. That swing keeps liquid at about 42-46 degrees.

Is it possible to bypass or completely replace the internal digital thermostat? Or somehow trick the internal thermometer into thinking it's warmer than it actually is?

Any advice would be great!

Yes you can replace the original thermostat with temp controller. You should be able to access all the wires you need near the compressor.

What kind of beverage cooler do you have?

I put an analog temp controller in-line with the hot lead that goes to the compressor. Took the orginal thermostat out.

It's a Vissani/masterchef beverage cooler.

I haven't look too much around the compressor yet but I did take a photo of the stock thermostat wiring. By process of elimination, I'm assuming the thicker Red/Blue/Brown wires connect to the compressor.

Any way of finding out which wires of those 3 should connect to the new thermostat control?

THANKS!

I read on an old post on another forum that adding a 1M-Ohm Potentiometer to the Thermometer wires (Black only) would allow adjustment of the thermometer, tricking the thermostat into making the unit colder... not sure if that is a good solution though.

Also found the wiring diagram for this unit:

looks like brown is one leg of the power coming in to the existing controller and red is power coming out of the controller as determined by the thermostat you are having trouble with. Electric guys, correct me if I'm wrong, but it looks like you would want to put the new thermostat in series (in between) that brown lead and the red wire. Looks like you would also need power coming off the brown to continue feeding into that little transformer if you wanted to keep the light operational as well.

I tried adding the potentiometer to the black temperature wires. After adjusting the knob and testing the results over time, I was successful in offsetting the temperature sensor's voltage. The thermostat was reading 10degF higher than the actual internal temp (eg thermostat reads 45, internal temp would actually be 35). However the compressor was randomly turning off when the internal temp got around 37-38... I found out this was due to the auto-defrost sensor (white wire). Adding another potentiometer to the white wire would solve this issue, but since there is no visual feedback on the thermostat regarding the defrost process, i knew trying to make blind adjustments to another knob would be an agonizing process that I didn't want to deal with.

I ended up cutting out the the internal thermostat circuitry and wired in a PID controller w/relay output using the red/brown/blue wires. I even used the old thermostats housing to hold the new PID controller in the same location as the original. It has been working great and sitting at 35degF with a 2degF hysteresis!

I plan on wiring a fan to the PID's alarm1 terminal and possibly a colored light to the alarm2 terminal (just for looks).

Can you post a picture of you PID wiring or a wiring diagram?

Can anyone post pictures of there set up? I am having troubles with my build please and thank you