Compressor Startup Failure - Mitsubishi Heavy Industries FDT71VNXWVH Service Manual

Error code
Indoor control PCB
Remote control:
E59
Outdoor control PCB
Outdoor inverter
1. Applicable model
2. Error detection method
When it fails to change over to
the operation for rotor position
detection of compressor motor
3. Condition of error displayed
If the compressor fails to startup
for 20 times (10 patterns × 2
times) continuously.
4. Presumable cause
• Outdoor fan motor anomaly
• Outdoor unit control PCB
anomaly
• Inverter PCB anomaly
• Anomalous power source
voltage
• Insufficient or excessive
refrigerant amount
• Faulty component for
refrigerant circuit
• Compressor anomaly
(Motor or bearing)
Note: Insulation resistance
• The unit is left for long period without power source or soon after installation, insulation resistance may decrease to several MΩ or lower due to the liquid refrigerant
migrated in the refrigerant oil in compressor. If the electric leakage breaker is activated due to low insulation resistance, check followings.
➀ Check whether the insulation resistance can recover or not, after 6 hours has passed since power ON.
(By energize the crankcase heater, liquid refrigerant migrated in the refrigerant oil in compressor can be evaporated)
➁ Check whether the electric leakage breaker conforms to high-harmonic specifications.
(As inverter PAC units has inverter, in order to prevent from improper operation, be sure to use the breaker of high-harmonic type)
LED Green
Keeps flashing
Keeps flashing
Yellow LED
PCB
Stays OFF
5. Troubleshooting
In case that the compressor
does not start at all and no
sound or vibration exists
power source voltage
OK?
YES
Is DC15V
detected between ② and
③ on CNI3?
Is DC15V
detected after disconnecting
outdoor fan motor?
Replace outdoor unit control PCB.
Can compressor startup?
Is the
pressure equalized
at starting OK?
YES
Is the insulation
resistance and resistance
between terminals(1) of
compressor OK?
YES
To next page
Red
Content
Stays OFF
5-time flash

Compressor startup failure (1/2)

Diagnosis
Is
Note(1) How to check voltage
at CN13 ⇒See E51
⑴
⑵
Note(2) Under anomalous
NO
conditions, the voltage
becomes less than
⑵
DC14V
NO
NO
(1) 0.722Ω or more at 20°C (Model FDC71VNX-W)
118
- -
'19 • PAC-SM-332
Countermeasure
Check the power source
NO
voltage and correct it.
Replace inverter PCB.
YES
If not solved yet, replace
noise filter PCB.
Replace outdoor fan motor.
YES
OK
YES
Check refrigerant amount
NO
and refrigerant circuit.
Replace compressor.
NO