Mitsubishi Outdoor Unit MUZ-HM09NA-U8

Ensure power is turned off to the outdoor inverter P.C. board

Gather necessary tools for cutting/soldering the JS wire

Select the current model and configuration

Choose the desired defrost finish temperature setting

Cut or solder the JS wire according to the selected setting

Inspect the soldering/cutting work for quality assurance

Pre-Heat Control Activation/Deactivation

Select the desired pre-heat control setting

Verify the JK wire is correctly cut or soldered based on the selected setting

Is the discharge temperature thermistor reading 68°F (20°C) or below?

Is the compressor energized when pre-heat control is activated?

Inverter P.C. Board Replacement Check

Check the jumper wires on the new inverter P.C. board

Ensure JK wire is cut/soldered as per the required setting