Green receive LED on solid
Terminal 1 / Terminal 2 mis-wire
This code typically points to
- Terminal 1 and Terminal 2 reversed at indoor unit/thermostat/outdoor unit
- Short between terminal 1 and terminal 2
- Short between terminal 1 or 2 and terminal C or R
Next checks to confirm
- Check communication wires terminal 1/terminal 2 and replace if needed
Escalation
Network wiring fault
Reset behavior
Clears after miswire/short is corrected.
Urgent
Fix now