Mitsubishi Outdoor Unit MUZ-HM24NA

Warning: This procedure requires trained personnel with PPE!

Enter the discharge temperature thermistor reading

If the discharge temperature thermistor is 68°F (20°C) or below, the pre-heat control turns ON.

Choose the pre-heat control setting

To activate the pre-heat control, cut JK wire of the inverter P.C. board.

To deactivate the pre-heat control, solder JK wire of the inverter P.C. board.

Check if the inverter P.C. board is replaced

If the inverter P.C. board is replaced, check the jumper wires, and cut/solder them if necessary.

Sign off on the pre-heat control setting

Warning: This procedure requires technical knowledge and should be performed by trained personnel only.

JS wire of the outdoor inverter P.C. board identified?

Choose the current setting of JS wire

Choose the desired defrost finish temperature

JS wire cut/soldered as per the desired setting?

Sign off on the defrost setting change