Mitsubishi Electric PUHZ-FRP71VHA2 Service Manual page 28

<Abnormalities detected while unit is operating>
Abnormal points and detection method
Check Code
High pressure (High pressure switch
63H operated)
Abnormal if high pressure switch 63H oper-
ated (4.15 MPa) during compressor opera-
tion.
63H: High pressure switch
U1
(1302)
High discharging temperature
High comp. surface temperature
Abnormal if discharge temperature
thermistor (TH4) exceeds 125°C or 110°C
continuously for 5 minutes.
Abnormal if condenser/evaporator
temperature thermistor (TH5) exceeds
U2
40°C during defrosting and discharge
(TH4: 1102)
temperature thermistor (TH4) exceeds
(TH33: 1132)
110°C.
Abnormal if comp. surface temperature
thermistor (TH33) exceeds 125°C or 110°C
continuously for 5 minutes.
Open/short circuit of discharge
temperature thermistor (TH4)/comp.
surface thermistor (TH33)
Abnormal if open (3°C or less) or short
U3
(217°C or more) is detected during
(TH4:5104)
compressor operation.
(TH33:5132)
(Detection is inoperative for 17 minutes
of compressor starting process and for 17
minutes after and during defrosting.)
OCH665B
Cause
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
operation 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
1 Disconnection or contact failure
of connector (TH4/TH33) on
the outdoor controller circuit
board
2 Defective thermistor
3 Defective outdoor controller
circuit board
28
Judgment and action
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: "10-10.
FUNCTION OF SWITCHES, CONNECTORS
AND JUMPERS".)
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 "10-6. HOW TO CHECK THE
PARTS".
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
displayed when the power is on again.
When U3 is displayed, refer to "Judgement
and action" for U3.
5 Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE
PARTS".
1 Check connection of connector (TH4/TH33)
on the outdoor controller circuit board.
Check breaking of the lead wire for thermistor
(TH4/TH33).Refer to "10-9. TEST POINT
DIAGRAM".
2 Check resistance value of thermistor (TH4/
TH33) or temperature by microprocessor.
(Thermistor/TH4/TH33: Refer to "10-6. HOW
TO CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer to "10-
10. FUNCTION OF SWITCHES, CONNECTORS
AND JUMPERS".)
3 Replace outdoor controller board.