Overriding compressor - why?

I noticed that some of you remove the control unit of the compressor and connect the compressor to the SSR - I wonder why this is required. The last 5 years I simply use the main power cord to start/stop the compressor, no changes done to the chest freezer at all. The temperature setting is set to maximum (lowest, I guess the sis -16 Celsius or so) and this seems to work as expected. Did I miss something?

Second question is if somebody has a single-line diagram for the control box.



This is freezer-dependent behavior. The thermostat may have its own built-in lockout period or control logic.
If your freezer reliably turns on and stays on, then great - you just have to interrupt the power supply. Interrupt an extension cord, and you don’t need to touch the freezer at all.
For one-size-fits-all guides we recommend bypassing the fridge/freezer thermostat because that’s guaranteed to work for every model.

The keyword here is freezer. If you want to cold crash with a fridge, you want to bypass the original temp control, because most fridges will not go to 1-2 degrees Celsius.
With a freezer there is no need, because it can be set to -18 and then giving the power cord power or the compressor directly is the same thing.

Yeah @Elco . I figured it had to be something like that. Can put that thought away now and focus on the control panel. Thanks.

Another reason would be if you hack a commercial fridge. They typically have their fans on continuously to circulate the air in the fridge. When I did mine, I put in a couple of toggle switches so I could override the SSR and force the compressor and the fan off independently. I typically turn the fan off when I am oxygenating, and turn both off when I am racking out.

Thanks, the keezers I make have a 220V fan, which run continuously - the control panel should just have a push-button that can start/stop the fan. Here a look inside the keezer. I have two of these, each of them will have its own control panel.