POWER lamp flashes 6-time.

The thermistors in the outdoor unit are abnormal.

G Check of outdoor thermistors

Disconnect the connector of thermistor in the outdoor P.C. board (see below table), and measure the resistance of thermistor.

Is the thermistor normal? (Refer to 10-6.1.)

 

No

 

Yes

 

 

 

 

 

 

Replace the thermistor except RT64. When RT64 is abnormal, replace the inverter P.C. board.

Reconnect the connector of thermistor.

Turn ON the power supply and press EMERGENCY OPERATION switch.

Does the unit operate for 10 minutes or more

 

 

 

 

 

 

 

Replace the inverter P.C. board.

 

without showing thermistor abnormality?

 

No

 

 

 

 

 

 

 

Yes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OK.

 

 

 

 

 

 

 

 

 

 

(Cause is poor contact.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Thermistor

Symbol

 

 

Connector, Pin No.

Board

Defrost

RT61

Between CN641 pin1 and pin2

 

 

Discharge temperature

RT62

Between CN641 pin3 and pin4

Inverter P.C. board

Fin temperature

RT64

Between CN642 pin1 and pin2

Ambient temperature

RT65

Between CN643 pin1 and pin2

 

 

Outdoor heat exchanger temperature

RT68

Between CN644 pin1 and pin3

 

 

H Check of R.V. coil

First of all, measure the resistance of R.V. coil to check if the coil is defective. Refer to 10-4.

In case CN721 is not connected or R.V. coil is open, voltage is generated between the terminal pins of the connector although any signal is not being transmitted to R.V. coil.

Check if CN721 is connected.

Unit operates COOL mode even if it is set to HEAT mode.

Disconnect connector (CN61) between the compressor and the intelligent power module.

Turn ON the power supply and press EMERGENCY OPERATION switch twice (HEAT mode).

Is there 230 VAC between CN721 and on the inverter P.C. board 3 minutes after the power supply is turned ON?

Yes

Replace the 4-way valve.

Replace the inverter No P.C. board.

Unit operates HEAT mode even if it is set to COOL mode.

Disconnect connector (CN61) between the compressor and the intelligent power module.

Turn ON the power supply and press EMERGENCY OPERATION switch once (COOL mode).

Is there 230 VAC between CN721 and on the inverter P.C. board 3 minutes after the power supply is turned ON?

No

Replace the 4-way valve.

Replace the inverter Yes P.C. board.

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Black & Decker MUZ-FD12NA- U1, MUZ-FD09NA- U1 service manual Check of outdoor thermistors, Check of R.V. coil