Long time in getting back to this, sorry! But have connected live and neutral directly to compressor (and earthed) and something is working. It’s making a bit of gurgling noise but I’ve left it running for now with a temp probe inside the fridge and will see if it brings the temp down. Assuming it does any suggestions on next steps? Do I just hook it up to an inkbird and let it flick the compressor on and off as needed?
Haven't got an inkbird but assuming it has a fridge protect delay setting there's no reason why it shouldn't work. I'd be amazed if it hasn't as STC-1000s have that setting.