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Check code Abnormal point and detection method
Actual tank temperature thermistor (TH5)
1 The unit is 3-minute resume preven-
tion mode if short/open of thermistor is
detected. Abnormal if the unit does not
reset normally after 3 minutes. (The
unit returns to normal operation, if it has
been reset normally)
2 Constantly detected during cooling,
P9
heating, heating ECO, anti freeze and
hot water operation.
Indoor unit failure during defrosting.
L3–LL
10-3. TROUBLESHOOTING
Phenomena
1. Remote controller display does not
work.
2. "Please Wait" display is remained on
the remote controller.
OCH755
1 Defective thermistor character-
istics
2 Contact failure of interface unit/
Flow temp. controller
Refer to the indoor unit's Instal-
lation Manual for TH5 connec-
tion.
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective PCB of interface unit/
Flow temp. controller
Indoor unit failure
Factor
1 1 2 VDC is not supplied to remote controller.
2 1 2–15 VDC is supplied to remote controller,
however, no display is indicated.
• "Please Wait" is not displayed.
• "Please Wait" is displayed.
1 At longest 2 minutes after the power supply
"Please Wait" is displayed to start up.
2 Communication error between the remote con-
troller and indoor unit
3 Communication error between the indoor and
outdoor unit
4 Outdoor unit protection device connector is
open.
Cause
1–3 Check resistance value of thermistor.
0: ... 15.0 k"
10: ..... 9.6 k"
20: ..... 6.3 k"
If you put force on (draw or bend) the lead wire
with measuring resistance value of thermistor,
breaking of wire or contact failure can be detected.
2 Check contact failure of Interface unit/Flow
temp. controller. Refer to the indoor unit's
Installation Manual.
Turn the power on again and check restart
after inserting connector again.
4 Check actual tank temperature display on
remote controller.
Replace PCB of Interface unit/Flow temp.
controller if there is abnormal difference with
actual tank temperature.
Turn the power off, and on again to operate after
check.
Refer to the indoor unit's service manual.
1 Check LED2 on indoor controller board.
(1) When LED2 is lit:
Check the remote controller wiring for break-
ing or contact failure.
(2) When LED2 is blinking:
Check short circuit of remote controller
wiring.
(3) When LED2 is not lit:
Refer to No.3 below.
2 Check the following.
• Failure of remote controller if "Please Wait" is
not displayed
• Refer to No.2 below if "Please Wait" is dis-
played.
1 Normal operation
2 Self-diagnosis of remote controller
3 "Please Wait" is displayed for 6 minutes
at most in the case of indoor/outdoor unit
communication error. Check LED3 on indoor
controller board.
(1) When LED3 is not blinking:
Check indoor/outdoor connecting wire for
miswiring. (Converse wiring of S1 and S2, or
break of S3 wiring.)
(2) When LED3 is blinking:
Indoor/outdoor connecting wire is normal.
4 Check LED display on outdoor controller
circuit board. Refer to "10-7. FUNCTION OF
SWITCHES, CONNECTORS AND JUMPERS".
Check protection device connector (63L and
63H) for contact failure. Refer to "10-6. TEST
POINT DIAGRAM".
30
Judgment and action
30: 4.3 k"
40: 3.0 k"
Countermeasure
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