Mitsubishi Heavy Industries FDC-VNA-W Series, User Manual

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Explanation of symbols



:  Conduct the cleaning and adjustment according to the inspection result



:  In case of abnormality after inspection, replace or repair the corresponding part.



:  Conduct the periodic replacement (consumable components)

:    Random  failure

 :  Wear-out failure

Part Name

Regular Inspection

Preventive Maintenance*

Remarks

Part Name

Details of Inspection

Inspection Method

Criteria <Standard>

Details of Maintenance

Inspection 

Interval

Maintenance Interval

(Used Hours/Duration)

Elapsed Years

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15

Electric and 
electronic 
parts

Crankcase heater

- Conductivity check

-  Insulation resistance measurement

- Appearance check

Tester

500 V mega

Visual inspection

-  It should be in a conducting state

-  The resistance value should be 1 M

Ω

 or more

-  There should be no abnormality

-  Replace it if it is not in a conducting state

-  Replace it if the resistance value is 1 M

Ω

 or less

Every year

Before the air 

conditioning 

season

8 years



Consumable 
components

Anti-freezing heater

- Conductivity check

-  Insulation resistance, appearance check

Tester

500 V mega, visual 

inspection

-  It should be in a conducting state

-  The resistance value should be 1 M

Ω

 or more, there 

should be no abnormality

-  Replace it if it is not in a conducting state

-  Replace it if the resistance value is 1 M

Ω

 or less

20,000 Hr



Electric component box 

(including inverter)

-  Circuit insulation resistance check

-  Terminal part, connector looseness check

500 V mega

Driver, visual inspection

-  The resistance value should be 1 M

Ω

 or more

-  There should be no looseness at the connecting part

-  Clean with a brush in case of extreme dust adhesion

-  Replace it if the resistance value is 1 M

Ω

 or less

-  Retighten or re-insert it if there is looseness

25,000 Hr



Electrolytic 

capacitor

-  Capacitor (electrolytic) appearance check

Visual inspection

-  There should be no liquid leakage or deformation

-  Appearance check, replace it if there is liquid leakage

Smoothing 

capacitor

-  Measurement of electrical capacitance and insulation 

resistance

- Appearance check

Electrostatic instrument, 

500 V mega Tester

-  Should be of speci

fi

 ed volume or more

-  The resistance value should be 1 M

Ω

 or more

-  Replace parts regularly

-  Replace it if the resistance value is 1 M

Ω

 or less

10 years



Consumable 
components

Terminal block

-  Terminal part screw looseness, deposit of dirt

Driver, visual inspection

-  It should not be loose

-  There should be no deposited foreign matter

-  Retighten it if it is loose.

-  Clean with a brush in case of deposited foreign matter 

adhesion

25,000 Hr



Electrical 

component

(including 

boards, etc.)

-  HIC board short circuit check

-  Visual check of dirt adhesion to the board, etc.

-  Self-diagnosis mode, appearance check

Tester

Visual inspection

Visual inspection

-  Should be of a speci

fi

 ed resistance value

-  There should be no deposited foreign matter

-  There should be no abnormal display

-  Replace it if it is outside the speci

fi

 ed resistance value

-  Clean with a brush in case of deposited foreign matter 

adhesion

-  Replace or correct the part

25,000 Hr



Pressure sensor, temperature 

sensor

-  Open, short circuit, earth, appearance check

Tester, visual inspection

-  Should be of a speci

fi

 ed resistance value

-  There should be no cracking or discoloration

-  Replace it in case of disconnection and short circuit

5 years



Switch, etc.

(including 

FFB, ELB)

Electromagnetic 

switch

Overcurrent relay

Auxiliary relay, etc.

-  Operation, appearance check

-  Rough contact surface

Visual inspection

Visual inspection

-  There should be no deformation

-  It should operate as prescribed, there should be no 

deformation

-  There should be no deformation or discoloration

-  Replace it in case of malfunction, deformation, and 

discoloration

25,000 Hr



Switching power source 

transformer

-  Output voltage measurement

Tester

-  Output voltage should be within a speci

fi

 ed value

-  Replace it if there is voltage abnormality

10 years



Cooling fan

-  Insulation resistance, abnormal sound generation

500 V mega, audible 

inspection

-  The resistance value should be 1 M

Ω

 or more, there 

should be no abnormal sound

-  Replace it if the resistance value is 1 M

Ω

 or less

-  Replace it in case of fan lock

20,000 Hr



Fuse

- Appearance check

Visual inspection

- There should be no deformation or discoloration

- Replace it when it is shutdown

10 years



Consumable 
components

Note 1)  Random fault is an unexpected failure which occurs before the wear is 

progressed, within the service life of the parts and equipment. It is difficult to 
establish a technological measure against the random fault. At the moment, 
statistical handling is the only measure against the random fault.

Note 2)  The elapsed year marked with * assumes the operating time as 10 hours/day and 

2500 hours/year in a normal operating condition without frequent start/stop. This 
may vary according to the operating condition. Please check the calculation basis 
of the elapsed year when making a maintenance contract.

Note 3) 

 illustrates the estimated timing when the wear-out failure starts 

and how the failure rate increases as the time passes.

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2022/6/23   13:25:39

2022/6/23   13:25:39