Mitsubishi Electric Mr.SERVICE PUHZ-HRP71VHA Service Manual page 36

<Abnormalities detected while unit is operating> <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
(1302)
High discharging temperature
(1) Abnormal if discharge temperature ther-
mistor (TH4) exceeds 125: or 110:
continuously for 5 minutes.
Abnormal if discharge temperature ther-
mistor (TH4) exceeds 110: or more
continuously for 30 seconds after 90
seconds have passed since the defrost-
ing operation started.
U2
(1102)
(2) Abnormal if discharge superheat
(Cooling: TH4 – TH5 / Heating: TH4 –
TH6) (V/YHA)
(Cooling: TH4 – T
T ) (V/YHA2)
63HS
exceeds 70: continuously for 10 min-
utes.
Open/short circuit of discharge
temperature thermistor (TH4)
Abnormal if open (3: or less) or short
(217: or more) is detected during
compressor operation.
(Detection is inoperative for 10 minutes
U3
of compressor starting process and for 10
(5104)
minutes after and during defrosting.)
1 Short cycle of indoor unit
2 Clogged filter of indoor unit
3 Decreased airflow caused by
dirt of indoor fan
4 Dirt of indoor heat exchanger
5 Locked indoor fan motor
6 Malfunction of indoor fan motor
7 Defective operation of stop
valve (Not full open)
8 Clogged or broken pipe
9 Locked outdoor fan motor
0 Malfunction of outdoor fan
motor
1 Short cycle of outdoor unit
2 Dirt of outdoor heat exchanger
3 Decreased airflow caused by
defective inspection of outside
temperature thermistor
(It detects lower temperature
than actual temperature.)
4 Disconnection or contact failure
of connector (63H) on outdoor
controller board
5 Disconnection or contact failure
of 63H connection
6 Defective outdoor controller
board
7 Defective action of linear
expansion valve
8 Malfunction of fan driving circuit
1 Overheated compressor opera-
tion caused by shortage of
refrigerant
2 Defective operation of stop
valve
3 Defective thermistor
4 Defective outdoor controller
board
5 Defective action of linear
expansion valve
6 Clogging with foreign objects in
refrigerant circuit
w Clogging occur in the parts
/ Heating: TH4 – which become below freez-
63HS
ing point when water enters in
refrigerant circuit.
1 Disconnection or contact
failure of connector (TH4) on
the outdoor controller circuit
board
2 Defective thermistor
3 Defective outdoor controller
circuit board
Case
1~6 Check indoor unit and repair defect.
7 Check if stop valve is fully open.
8 Check piping and repair defect.
9~2 Check outdoor unit and repair defect.
3 Check the detected temperature of outside
temperature thermistor on LED display.
(SW2 on A-Control Service Tool : Refer to
11-10.)
4~6 Turn the power off and check F5 is
displayed when the power is turned again.
When F5 is displayed, refer to "Judgment
and action" for F5.
7 Check linear expansion valve.
Refer to 11-6.
8 Replace outdoor controller board.
1 Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
2 Check if stop valve is fully open.
34 Turn the power off and check if U3 is dis-
played when the power is turned on again.
When U3 is displayed, refer to "Judgement
and action" for U3.
5 Check linear expansion valve.
Refer to 11-6.
6 After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
1 Check connection of connector (TH4) on the
outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (TH4). Refer to 11-9.
2 Check resistance value of thermistor (TH4)
or temperature by microprocessor.
(Thermistor/TH4: Refer to 11-6.)
(SW2 on A-Control Service Tool: Refer to 11-10.)
3 Replace outdoor controller board.
36
Judgment and action