Mitsubishi Outdoor Unit MUZ-HM15NA2

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.

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

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

Is the JS wire of the outdoor inverter P.C. board accessible?

Select the current setting of the JS wire

Based on the model and current setting, refer to the procedure description for the corresponding defrost finish temperature.

Was the defrost setting changed successfully?

Sign off on the defrost setting change