First, check the basics — is the machine plugged in and turned on, and is the water supply connected with the valve open? If those check out, the most common culprits are clogged or unchanged water filters causing mineral and lime scale buildup, which can cause water inlet valves to stick and leave the machine stuck in harvest mode without producing ice. Other causes include a faulty thermostat, refrigerant leak, or failed harvest sensor. If basic checks don’t resolve it, call a factory certified technician — attempting to self-diagnose compressor or refrigerant issues can cause further damage.