Mitsubishi Electric PUZ-HWM140VHA Service Manual page 22

<Abnormalities detected while unit is operating>
Check Code Abnormal point and detection method
High pressure (High pressure switch
63H operated)
Abnormal if high pressure switch 63H
operated (*) during compressor operation.
*4.15 MPa
63H: High pressure switch
U1
(1302)
High discharge temperature
Abnormal if discharge temperature
thermistor (TH4) exceeds 125°C or 110°C
continuously for 5 minutes.
Abnormal if during defrosting discharge
temperature thermistor (TH4) exceeds
110°C continuously for 30 minutes.
High comp. surface temperature
Abnormal if comp. surface temperature
U2
(TH33) exceeds 125°C or 110°C continu-
(TH4: 1102)
ously for 5 minutes.
(TH33: 1103)
In the case of high comp. surface tem-
perature error, compressor does not restart
unless the thermistor (TH33) becomes less
than 95°C.
Open/short circuit of discharge temperature
thermistor (TH4)/comp. surface thermistor
(TH33)
Abnormal if open (3°C or less) or short
(217°C or more) is detected during
compressor operation.
(Open (3°C or less) detection is inoperative
for 10 minutes of compressor starting
U3
process and for 10 minutes after or during
(TH4: 5104)
defrosting.)
(TH33: 5132)
OCH748
Cause
1 Decreased water flow
2 Clogged filter of water pipe
3 Dirt of plate heat exchanger
4 Locked water pump
5 Malfunction of water pump
6 Clogged or broken pipe
7 Locked outdoor fan motor
8 Malfunction of outdoor fan
motor
9 Short cycle of outdoor unit
0 Dirt of outdoor heat exchanger
1 Decreased airflow caused by
defective inspection of outside
temperature thermistor
(It detects lower temperature
than actual temperature.)
2 Disconnection or contact
failure of connector (63H) on
outdoor controller board
3 Disconnection or contact fail-
ure of 63H connection
4 Defective outdoor controller
board
5 Defective operation of linear
expansion valve
6 Malfunction of fan driving cir-
cuit
1 Overheated compressor oper-
ation caused by insufficient
refrigerant
2 Defective thermistor
3 Defective outdoor controller
board
4 Defective operation of linear
expansion valve
5 In the case of the unit does
not restart:
Detection temp. of thermistor
(TH33) ] 95°C
1 Disconnection or contact fail-
ure of connector (TH4/TH33)
on the outdoor controller cir-
cuit board
2 Defective thermistor
3 Defective outdoor controller
circuit board
22
Judgment and action
1–5 Check water circuit and repair the defect.
6 Check piping and repair the defect.
7–0 Check outdoor unit and repair the defect.
1 Check the detected temperature of outside
temperature thermistor on LED display.
(SW2: Refer to "9-8. OUTDOOR UNIT
OPERATION MONITOR FUNCTION".)
2–4 Turn the power off and check F5 is
displayed when the power is turned on
again.
When F5 is displayed, refer to "Judgment
and action" for F5.
5 Check linear expansion valve.
Refer to "9-6. HOW TO CHECK THE
COMPONENTS".
6 Replace outdoor controller board.
1 Check intake super heat.
Check leakage of refrigerant.
Charge additional refrigerant.
23 Turn the power off and check if U3 is
displayed when the power is turned ON
again.
When U3 is displayed, refer to "Judgment
and action" for U3.
4 Check linear expansion valve.
Refer to "9-6. HOW TO CHECK THE
COMPONENTS".
1 Check connection of connector (TH4/TH33)
on the outdoor controller circuit board.
Check the lead wire for thermistor (TH4/
TH33). Refer to "9-7. TEST POINT
DIAGRAM".
2 Check resistance value of thermistor (TH4/
TH33) or temperature on LED display.
(Thermistor/TH4/TH32: Refer to "9-6. HOW
TO CHECK THE COMPONENTS".)
(SW2: Refer to "9-8. OUTDOOR UNIT
OPERATION MONITOR FUNCTION".)
3 Replace outdoor controller board.