Mitsubishi Electric MXZ-8A140VA Technical & Service Manual page 49

Abnormal point and detection method
Error Code
Current sensor error
Abnormal if current sensor detects –1.5A
to 1.5A during compressor operation. (This
error is ignored in case of test run mode.)
UH
(5300)
Abnormal if input current exceeds 38 A or
34A continuously 10 seconds.(Current sen-
sor on noise filter board detects input current)
Low pressure (63L worked)
Abnormal if 63L is worked (under-
0.03MPa) during compressor operation.
63L: Low-pressure switch
UL
(1300)
Compressor overcurrent interruption
Abnormal if overcurrent DC bus or com-
pressor is detected after compressor
starts operating for 30 seconds.
UP
(4210)
Remote controller communication error
(Signal receiving error)
(1) Abnormal if any signal from IC of refrig-
erant address "0" could not be normally
received for 3 minutes.
(2) Abnormal if sub remote controller could
E0
not receive any signal for 2 minutes.
(No display)
Remote controller communication error
(Transmitting error)
(1) Abnormal if sub remote controller could
E3
not find blank of transmission path for 6
(No display)
seconds.
(2) Abnormal if remote controller could not
finish transmitting 30 times continuously.
Indoor - branch box/branch box -
outdoor unit communication error
(Signal receiving error)
(Branch box/outdoor unit)
(1) Abnormal if branch box/outdoor con-
E8
troller circuit board could not receive
(6840)
anything normally for 3 minutes.
Case
1 Disconnection of compressor
wiring
2 Defective circuit of current
sensor on outdoor power
circuit board
1Decrease of power supply volt-
age
1 Stop valve of outdoor unit is
closed during operation.
2 Disconnection or loose connec-
tion of connector (63L) on out-
door controller board
3 Disconnection or loose connec-
tion of 63L
4 Defective outdoor controller board
5 Leakage or shortage of refrigerant
6 Malfunction of linear expansion
valve
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
1 Defective communication cir-
cuit of remote controller
2 Defective communication cir-
cuit of indoor controller board
of refrigerant address "0"
3 Noise has entered into transmis-
sion line of remote controller.
4 All remote controllers are set
as "sub" remote controller. In
this case, E4 is displayed at
outdoor LED, and E0 is dis-
played at remote controller.
1 Defective communication cir-
cuit of remote controller
2 Noise has entered into trans-
mission line of remote controller.
3 Two remote controllers are set
as "main."
(In case of 2 remote controllers)
1 Contact failure of indoor/out-
door unit connecting wire
2 Defective communication circuit
of branch box/outdoor controller
circuit board
3 Defective communication cir-
cuit of indoor/branch box con-
troller board
4 Noise has entered into
indoor–branch box/branch box–
outdoor unit connecting wire.
49
Judgment and action
1 Correct the wiring (U·V·W phase) to com-
pressor. Refer to 9-7.
2 Replace outdoor power circuit board.
1Check the facility of power supply.
1 Check stop valve.
2~4 Turn the power off and on again to check
if F3 is displayed on restarting.
If F3 is displayed, follow the F3 process-
ing direction.
5 Correct to proper amount of refrigerant.
6 Check linear expansion valve. Refer to 9-6.
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U·V·W phase) to com-
pressor. Refer to 9-7.
4 Check indoor/outdoor fan.
5 Solve short cycle.
6 Replace outdoor controller circuit board.
7 Check compressor. Refer to 9-6.
W Before the replacement of the outdoor con-
troller circuit board, disconnect the wiring for
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
voltage check with same performing frequen-
cy.
1~3 Diagnose remote controller.
Take actions as follows according to
diagnosis result.
a) When "RC OK" is displayed,
remote controllers have no problem.
Turn the power off, and on again to
check. If, "PLEASE WAIT" or "H0" is
displayed for 4 minutes or more,
replace indoor controller board.
b) When "RC NG" is displayed,
replace remote controller.
c) When "RC E3" or "ERC 00-66" is dis-
played, noise may be causing abnor-
mality.
4 Set a remote controller to main, and the
other to sub.
w The descriptions above, 1-3, are for E0 and
E3.
1 Check disconnection or looseness of indoor–
branch box/branch box–outdoor unit
connecting wire of indoor or branch box or
outdoor units.
2~4 Turn the power off, and on again to
check. Replace indoor controller board or
branch controller board or outdoor con-
troller circuit board if abnormality is dis-
played again.