Power Transistor Overheat - Mitsubishi Electric FDF71VNXVD Technical Manual

Error code
Indoor control PCB
Remote controller: E41
Outdoor control PCB
1. Applicable model
FDC71 ～ 140 models
2. Error detection method
When less than 14VDC of
the output voltage is detected
between ➁ and ➂ on CNI3, E41
is displayed. (See "Note"
mentioned below)
3. Condition of Error displayed
When less than 14VDC of
the output voltage is detected
between ➁ and ➂ on CNI3, E41
is displayed. (See "Note"
mentioned below)
4. Presumable cause
• Inverter PCB anomaly
• Outdoor fan motor anomaly
• Control PCB anomaly
• Noise filter PCB anomaly
Note : The "Single phase models" of inverter PAC have no function to output the signal for the power transistor overheat.
However since the power source for the power transistor and the outdoor fan motor is in the same line,
when the anomaly of the outdoor fan motor occurs, E41 is displayed.
LED Green
Keeps flashing
Keeps flashing
Outdoor
Yellow
inverter
6 times flash
PCB
5. Troubleshooting
① Single phase models (FDC71-140)
deteted after disconnecting
Note (2) How to check the voltage between � and � of CNI3?
See E51
② 3-phase models (FDC100-140)
E41 Replace inverter PCB
Red
Content
Stays OFF

Power transistor overheat (1/2)

1 time flash
(Model FDC71 ～ 140 only)
Diagnosis
(1) (2)
Is DC15V detected
between � and � on
CNI3?
Note (1): Under annomalous conditions,
NO
the voltage becomes less than 14VDC.
(1)
Is DC15V
outdoor fan motor?
180
– –
'11 • PAC-T-160
Countermeasure
Replace INV PCB
YES
If not solved, replace
Noise filter PCB as well
Replace outdoor fan motor
YES
Replace control PCB
NO
If not solved, replace
INV PCB as well