Mitsubishi Electric PUHZ-SW75VHA.UK Service Manual page 31

Error Code Abnormal point and detection method
Freezing/overheating protection is working
Overheating protection <Heating mode>
Abnormal if condensing temperature of
pressure sensor (63HS) detects
Tcond. °C or more and compressor
operation frequency is less than or equal
to 25 Hz. Detection is inoperative during
defrosting.
Tcond
P6
stage-g
-18 -17
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.
11-4. TROUBLESHOOTING
Phenomena
1. Remote controller display does not
work.
2. "PLEASE WAIT" display is remained
on the remote controller.
OCH533B
1 Overcharge of refrigerant
2 Defective refrigerant circuit (clogs)
3 Malfunction of linear expansion valve
4 Reduced water flow
· Clogged filter
· Leakage of water
5 High temperature
· Over-load
· Inlet water is too warm.
6 Defective water pump
stage-e
stage-f
-15 -14 -12 -11
stage-a stage-b stage-c stage-d stage-e stage-f stage-g
Tcond
63 61
SW75
SW100/120 63 62
1 Defective thermistor character-
istics
2 Contact failure of TB61 No. 5-6
on PCB of interface unit/Flow
temp. controller
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective PCB of interface
unit/Flow temp. controller
1 DC12V is not supplied to remote controller.
(Power supply display
2 DC12~15V 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 controller
and indoor unit
3 Communication error between the indoor and outdoor
unit
4 Outdoor unit protection device connector is open.
Case
stage-c
stage-d
-9 -8 -6
60 58 56 53
61 60 59 57
Factor
is not indicated on LCD.)
31
Judgment and action
12 Check operating condition of refrigerant
circuit.
3 Check linear expansion valve.
45 Check water piping.
6 Check water pump.
stage-a
stage-b
-5 -3 -2 Ambient temperature
50
51
1–3 Check resistance value of thermistor.
0: ... 15.0k"
30: ..... 4.3k"
10: ..... 9.6k"
40: ..... 3.0k"
20: ..... 6.3k"
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 TB61 No.5-6 on PCB
of Interface unit/Flow temp. controller. Refer to
8. WIRING DIAGRAM.
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.
Countermeasure
1 Check LED2 on indoor controller board.
(1) When LED2 is lit.
Check the remote controller wiring for
breaking 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 displayed.
1 Normal operation
2 Self-diagnosis of remote controller
3 "PLEASE WAIT" is displayed for 6 minutes
at most in 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 11-8.
Check protection device connector (63L
and 63H) for contact failure. Refer to 11-7.