Abnormal Low Pressure (63L Worked); Remote Controller Transmission Error(E0)/Signal Receiving Error(E4); Remote Controller Control Board - Mitsubishi Electric SUZ-KA24NAHZ Service Manual

Abnormal point and detection method
Check Code

Abnormal low pressure (63L worked)

Abnormal if 63L is worked (under −4 PSIG
[−0.03 MPa]) 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 transmission
error(E0)/signal receiving error(E4)
1 Abnormal if main or sub remote control-
ler cannot receive normally any trans-
mission from indoor unit of refrigerant
address "0" for 3 minutes.
(Check code: E0)
2 Abnormal if sub-remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
1 Abnormal if indoor controller board can
not receive any data normally from
E0
remote controller board or from other
or
indoor controller board for 3 minutes.
E4
(Check code: E4)
2 Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)

Remote controller control board

1 Abnormal if data cannot be read nor-
mally from the nonvolatile memory of the
remote controller control board.
E1
(Check code: E1)
or
E2
2 Abnormal if the clock function of remote
controller cannot be operated normally.
(Check code: E2)
OCH754A
Cause
1 Stop valve of outdoor unit is
closed during operation.
2 Disconnection or loose con-
nection of connector (63L) on
outdoor controller board
3 Disconnection or loose connec-
tion of 63L
4 Defective outdoor controller
board
5 Leakage or shortage of refriger-
ant
6 Malfunction of linear expansion
valve
1 Stop valve of outdoor unit is
closed.
2 Decrease of power supply voltage
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
outdoor controller board
7 Defective compressor
8 Defective outdoor power circuit
board
9 Dip switch setting difference of
outdoor controller circuit board
1 Contact failure at transmission
wire of remote controller
2 All remote controllers are set
as "sub" remote controller.
In this case, E0 is displayed
on remote controller, and E4
is displayed at LED (LED1,
LED2) on the outdoor controller
circuit board.
3 Miswiring of remote controller
4 Defective transmitting receiving
circuit of remote controller
5 Defective transmitting receiv-
ing circuit of indoor controller
board of refrigerant address "0".
6 Noise has entered into the
transmission wire of remote
controller.
1 Defective remote controller
32
Judgment and action
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 "10-5.
HOW TO CHECK THE PARTS".
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U V W phase) to com-
• •
pressor. Refer to "10-8. TEST POINT
DIAGRAM". (Outdoor power circuit board).
4 Check indoor/outdoor fan.
5 Solve short cycle.
6 Replace outdoor controller circuit board.
7 Check compressor. Refer to "10-5. HOW TO
CHECK THE PARTS".
Before the replacement of the outdoor controller cir-
cuit 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 voltage
check with same performing frequency.
8 R eplace outdoor power circuit board
9 Check the dip switch setting of outdoor con-
troller circuit board
1 Check disconnection or looseness of indoor
unit or transmission wire of remote controller.
2 Set one of the remote controllers "main".
If there is no problem with the action above.
3 Check wiring of remote controller.
• Total wiring length: max. 1640 ft [500 m]
(Do not use cable with 3 or more cores.)
• The number of connecting indoor units:
max.16 units
• The number of connecting remote control-
ler: max. 2 units
If the cause of trouble is not any of 1–3
above, diagnose 4–6 by remote controllers.
a) When "OK" is displayed, remote control-
lers have no problem.
Turn the power off, and on again to check.
If abnormality occurs again, replace
indoor controller board.
b) When "NG" is displayed, replace remote
controller.
c) When "E3" or "ERC" is displayed, noise
may be causing abnormality.
Note: If the unit is not normal after replacing
indoor controller board in group control,
indoor controller board of address "0"
may be abnormal.
1 Replace remote controller.