Mitsubishi Electric PUHZ-W50VHA-BS Service Manual page 46

<Abnormalities detected while unit is operating>
Abnormal point and detection method
Error Code
High pressure (High-pressure switch
63H operated)
Abnormal if high-pressure switch 63H oper-
ated ( w ) during compressor operation.
w 4.15 MPa
63H: High-pressure switch
U1
High discharging temperature
Abnormal if discharge temperature
thermistor (TH4) exceeds 125: or 110:
continuously for 5 minutes.
Abnormal if during defrosting discharge
temperature thermistor (TH4) exceeds
110: continuously for 30 minutes.
High comp. surface temperature
U2
(W50VHA, W50VHAR1, W50VHAR2,
W85VHAR1, HW112YHA2R3,
HW140VHA2R3 and HW140YHA2R3)
Abnormal if comp. surface temperature
(TH33/H34) exceeds 125:.
In the case of high comp. surface tem-
perature error, compressor does not
restart unless the thermistor (TH33/TH34)
becomes less than 95:.
Open/short circuit of discharge
temperature thermistor (TH4)/comp.
surface thermistor (TH33/W50VHA,
W50VHAR1, W50VHAR2 and
W85VHAR1), (TH34/HW112YHA2R3,
HW140VHA2R3 and HW140YHA2R3)
Abnormal if open (3: or less) or short
U3
(217: or more) is detected during
compressor operation.
(Open (3: or less) detection is inoperative
for 10 minutes of compressor starting
process and for 10 minutes after or during
defrosting.)
OCH439H
Case
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 failure
of 63H connection
4 Defective outdoor controller
board
5 Defective operation of linear
expansion valve
6 Malfunction of fan driving circuit
1 Overheated compressor
operation 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:
1 Disconnection or contact failure
of connector (TH4/TH33/TH34)
on the outdoor controller circuit
board.
2 Defective thermistor
3 Defective outdoor controller
circuit board
46
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- 9-7.)
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 9-5.
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 "Judgement
and action" for U3.
4 Check linear expansion valve.
Refer to 9-5.
1 Check connection of connector (TH4/TH32)
on the outdoor controller circuit board.
Check the lead wire for thermistor (TH4/
TH32). Refer to 9-6.
2 Check resistance value of thermistor (TH4/
TH32) or temperature on LED display.
(Thermistor/TH4/TH32: Refer to 9-5.)
(SW2: Refer to 9-7.)
3 Replace outdoor controller board.