Mitsubishi Electric PUHZ-FRP71VHA Service Manual page 34

Abnormal point and detection method
Error Code
Over heat protection
Abnormal if outdoor pipe thermistor (TH3)
detects 70: or more during compressor
operation.
Ud
(1504)
Abnormal pressure of pressure sensor
(63HS)
Abnormal if pressure sensor (63HS)
detects 0.1 MPa or less.
Detection is inoperative for 3 minutes after
UE
compressor starting and 3 minutes after
(1509)
and during defrosting.
Compressor overcurrent interruption
(When compressor locked)
Abnormal if overcurrent of DC bus or
compressor is detected within 30 seconds
after compressor starts operating.
UF
(4100)
Current sensor error or input current error
• Abnormal if 38A of input current is
detected or 34A or more of input current
is detected for 10 seconds continuously.
UH
(5300)
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or com-
pressor is detected after compressor starts
operating for 30 seconds.
UP
(4210)
OCH544
Case
1 Defective outdoor fan (fan
motor) or short cycle of outdoor
unit during cooling operation
2 Defective outdoor pipe
thermistor (TH3)
3 Defective outdoor controller
board
1 Disconnection or contact
failure of connector (63HS) on
the outdoor controller circuit
board
2 Defective pressure sensor
3 Defective outdoor controller
circuit board
1 Stop valve is closed.
2 Decrease of power supply
voltage
3 Looseness, disconnection or
converse of compressor wiring
connection
4 Defective compressor
5 Defective outdoor power board
6 Dip switch setting difference of
outdoor controller circuit board.
1 Defective circuit of current
sensor on outdoor power circuit
board
2 Decrease of power supply
voltage
1 Stop valve of outdoor unit is
closed.
2 Decrease of power supply volt-
age
3 Looseness, disconnection or
converse of compressor wiring
connection
4 Defective fan of indoor/outdoor
units
5 Short cycle of indoor/outdoor
units
6 Defective input circuit of out-
door controller board
7 Defective compressor
8 Defective outdoor power circuit
board
9 Dip switch setting difference of
outdoor controller circuit board
34
Judgment and action
1 Check outdoor unit air passage.
23 Turn the power off and on again to check
the error code. If U4 is displayed, follow the
U4 processing direction.
1 Check connection of connector (63HS) on
the outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (63HS).
2 Check pressure by microprocessor.
(Pressure sensor/ 63HS)
(SW2: Refer to 10-10.)
3 Replace outdoor controller board.
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U V W phase) to
• •
compressor.
Refer to 10-9 (Outdoor power circuit board).
4 Check compressor. Refer to 10-6.
5 Replace outdoor power circuit board.
6 Check the dip switch setting of outdoor
controller circuit board.
Refer to "Model Select" in "1) Function of
switches" in 10-10.
1 Replace outdoor power circuit board.
2 Check the facility of power supply.
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U V W phase) to com-
• •
pressor. Refer to 10-9 (Outdoor power circuit
board).
4 Check indoor/outdoor fan.
5 Solve short cycle.
6 Replace outdoor controller circuit board.
7 Check compressor. Refer to 10-6.
* Before the replacement of the outdoor con-
troller circuit board, disconnect the wiring to
compressor from the outdoor power circuit
board and check the output voltage among
phases, U, V, W, during test run. No defect on
board if voltage among phases (U-V, V-W and
W-U) is same. Make sure to perform the volt-
age check with same performing frequency.
8 Replace outdoor power circuit board
9 Check the dip switch setting of outdoor con-
troller circuit board