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7
Water to Water Heat Pump (WTW)
7.8 Service and Maintenance
The heat pump unit must be serviced once a year by a qualified individual. Servicing and maintenance of the outdoor unit should only be done by a Mitsubishi Electric
trained technician with relevant qualifications and experience. Any electrical work should be done by a trades person with the appropriate electrical qualifica-tions. Any
maintenance or 'DIY' fixes done by a non-accredited person could invalidate the Warranty and/or result in damage to the heat pump unit and injury to the per-son.
Basic Troubleshooting
No.
Fault symptom
1
Main remote controller
1. There is no power supply to main remote
display is blank.
controller.
2. Power is supplied to main remote controller,
however, the display on the main remote
controller does not appear.
2
"Please Wait" remains
1. "Please Wait" is displayed for up to 6 minutes.
displayed on the main
2. Communication failure between the main
remote controller.
remote controller and FTC
3. Communication failure between FTC and
controller circuit board
3
The main screen
The main remote controller operations do not
appears with a press
work for a while after the settings are changed
of the "ON" button, but
in the service menu. This is because the system
disappears in a second.
takes time to apply the changes.
4
LED2 on FTC is off.
When LED1 on FTC is also off. (See "7.2 Wiring
(See "7.2 Wiring
diagrams".)
diagrams".)
1. The controller circuit board unit is not
supplied at the rated voltage.
2. Faulty connector wiring
3. FTC failure
When LED1 on FTC is lit.
Incorrect setting of refrigerant address.
(None of the refrigerant address is set to "0".)
5
LED2 on FTC is
When LED1 is also blinking on FTC .
blinking.
(See "7.2 Wiring
diagrams".)
When LED1 on FTC is lit.
1. Short-circuited wiring in main remote con-
troller
2. Main remote controller failure
6
LED4 on FTC is off.
1. SD memory card is NOT inserted into the
(See "7.2 Wiring
memory card slot with correct orientation.
diagrams".)
2. Not an SD standards compliant memory
card.
LED4 on FTC is
1. Full of data.
blinking.
2. Write-protected.
(See "7.2 Wiring
3. NOT formatted.
diagrams".)
4. Formatted in NTFS file system.
Possible cause
Faulty wiring between FTC and controller
circuit board
Explanation - Solution
1. Check LED2 on FTC. (See "5. WIRING DIAGRAM".)
(i) When LED2 is lit.
Check for damage or contact failure of the main remote controller wiring.
(ii) When LED2 is blinking.
Refer to No. 5 below.
(iii) When LED2 is not lit.
Refer to No. 4 below.
2. Check the following:
• Disconnection between the main remote controller cable and the FTC
control board
• Failure of the main remote controller if "Please Wait" is not displayed.
• Refer to No. 2 below if "Please Wait" is displayed.
1. Normal operation
2,
Main remote controller start up checks/procedure.
(i) If "0%" or "50–99%" is displayed below "Please Wait" there is a
3.
communication error between the main remote controller and the FTC
control board.
• Check wiring connections on the main remote controller.
• Replace the main remote controller or the FTC control board.
(ii) If "1–49%" is displayed there is a communication error between controller
circuit board and FTC control board.
• Check the wiring connections on the controller circuit board and the FTC
control board.
(Ensure the wiring connections between CN1 on the FTC control board and
CNS on the controller circuit board)
• Replace the controller circuit board and/or the FTC control board.
Normal operation
The FTC is applying updated settings made in the service menu. Normal
operation will start shortly.
1. Check the voltage across the terminals L and N or L3 and N on the controller
circuit board (See "7.4 Field wiring".)
• When the voltage is not 220 to 240 V AC, check wiring of the unit and of
the breaker.
• When the voltage is at 220 to 240 V AC, go to "2." below.
• Check the N.F.board and TB1 cable.
2. Check the voltage across the outdoor unit terminals S1 and S2. (See "7.4
Field wiring".)
• Check the cable between the terminals and N.F. board
• Check the cable between CNAC1 of the N.F.board and CNAC of the
controller circuit board.
• Check the cable between CN01 of the FTC board and CNS of the controller
circuit board.
3. Check the FTC control board.
• Check the fuse on FTC control board.
• Check for faulty wiring.
• If no problem found with the wiring, the FTC control board is faulty.
Set the refrigerant address to "0".
(Set refrigerant address using SW1(3-6) on controller circuit board.)
Check for faulty wiring between FTC and controller circuit board.
1., 2.
Remove main remote controller wires and check LED2 on FTC. (See "7.2
Wiring diagrams".)
• If LED2 is blinking check for short circuits in the main remote controller wiring.
• If LED2 is lit, wire the main remote controller again and:
- if LED2 is blinking, the main remote controller is faulty;
- if LED2 is lit, faulty wiring of the main remote controller has been corrected.
1. Correctly insert SD memory card in place until a click is heard.
2. Use an SD standards compliant memory card. (Refer to installation manual,
"7.4.6 Using SD memory card".)
1. Move or delete data, or replace SD memory card with a new one.
2. Release the write-protect switch.
3. Refer to installation manual, "7.4.6 Using SD memory card".
4. FTC control board is Not compatible with NTFS file system. Use an SD mem-
ory card formatted in FAT file system.
B-255
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