Troubleshooting By Inferior Phenomena - Mitsubishi Electric EHST17D-VM2D Service Manual

10-5. Troubleshooting by inferior phenomena

No. Fault symptom
1 Main remote controller 1. There is no power supply to main remote
display is blank.
2. Power is supplied to main remote
2 "Please Wait" remains 1. "Please Wait" is displayed for up to 6
displayed on the main
remote controller.
2. Communication failure between the main
3. Communication failure between FTC and
3 The main screen The main remote controller operations do
appears with a press not work for a while after the settings are
of the "ON" button, but changed in the service menu. This is because
disappears in a second. the system takes time to apply the changes.
4 LED2 on FTC is off. When LED1 on FTC is also off. (See "6.
(See "6. WIRING WIRING DIAGRAM".)
DIAGRAM".) <FTC powered via outdoor unit.>
1. The outdoor unit is not supplied at the
2. Defective outdoor controller circuit board
3. FTC is not supplied with 220 to 240 V
4. FTC failure
5. Faulty connector wiring
OCH714A
Possible cause
controller.
controller, however, the display on the
main remote controller does not appear.
minutes.
remote controller and FTC
outdoor unit
rated voltage.
AC.
1. Check LED2 on FTC. (See "6. 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, 3. Main remote controller start up checks/procedure.
(i) If "0%" or "50 to 99%" is displayed below "Please Wait" there is a
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 to 49%" is displayed there is a communication error between the
outdoor unit's and FTC's control boards.
• Check the wiring connections on the outdoor unit control board and the FTC
control board.
(Ensure S1 and S2 are not cross-wired and S3 is securely wired with no
damage. (See "7. FIELD WIRING".)
• Replace the outdoor unit's and/or the FTC's control boards.
Normal operation
The indoor unit 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 outdoor
power board. (See "7. FIELD WIRING".)
• When the voltage is not 220 to 240 V AC, check wiring of the outdoor unit and
of the breaker.
• When the voltage is at 220 to 240 V AC, go to "2." below.
2. Check the voltage across the outdoor unit terminals S1 and S2. (See "7. FIELD
WIRING".)
• When the voltage is not 220 to 240 V AC, check the fuse on the outdoor
control board and check for faulty wiring.
• When the voltage is 220 to 240 V AC, go to "3." below.
3. Check the voltage across the indoor unit terminals S1 and S2. (See "7. FIELD
WIRING".)
• When the voltage is not 220 to 240 V AC, check FTC-outdoor unit wiring for
faults.
• When the voltage is 220 to 240 V AC, go to "4." below.
4. 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.
5. Check the connector wiring.
• When the connectors are wired incorrectly, re-wire the connectors referring to
below. (See "7. FIELD WIRING".)
L
Initial settings
N
(Power
supplied by
S1
outdoor unit)
S2
S3
55
Explanation - Solution
White
CN01
Cylinder unit
control board