Just an update – ran the compressor for 30 minutes, both the evaporator and condenser stayed at room temp for the duration of the test. The compressor was hot to touch, and the pipe from the top (no idea whether that’s feed or return?) was also hot. The other pipe was marginally below room temp (maybe 1-2c less). Anyway, after watching the same test on a YT channel, I suspect the compressor isn’t working, which means the machine is written off after just 3 years (doesn’t appear to be a replaceable part – at least not for DIY anyway given the refrigerant).