Mitsubishi Electric Mr.Slim PCA-M35KA2 Service Manual page 25

Check Code Abnormal point and detection method
Freezing/overheating protection is working
(1) Freezing protection
Plate HEX Liquid temperature (TH34)
or refrigerant saturation temperature is
10 seconds smaller than the threshold.
The threshold is dynamically calculated
by inner operation using the operating
time of the compressor and the water
temperature.
P9
Remote controller transmission
error(E0)/signal receiving error(E4)
Abnormal if main or sub remote con-
troller cannot receive any transmission
normally from indoor unit of refrigerant
address "0" for 3 minutes.
(Check code: E0)
Abnormal if sub remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
Abnormal if indoor controller board
cannot receive any data normally from
E0
remote controller board or from other
or
indoor controller board for 3 minutes.
E4
(Check code: E4)
Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
Remote controller transmission
error(E3)/signal receiving error(E5)
Abnormal if remote controller could not
find blank of transmission path for 6
seconds and could not transmit.
(Check code: E3)
Remote controller receives transmitted
data at the same time and compares the
received and transmitted data. Abnormal
E3
if these data are judged to be different
or
30 continuous times. (Check code: E3)
E5
Abnormal if indoor controller board could
not find blank of transmission path.
(Check code: E5)
Indoor controller board receives trans-
mitted data at the same time and com-
pares the received and transmitted data.
Abnormal if these data are judged to be
different 30 continuous times. (Check
code: E5)
OCH752
Cause
Defective thermistor
characteristics
Contact failure of connector
(CN44) on the indoor controller
board (Insert failure)
Breaking of wire or contact
failure of thermistor wiring
Temperature of thermistor is
90˚C or more or −40˚C or less
caused by defective refrigerant
circuit.
Defective indoor controller
board
Contact failure at transmission
wire of remote controller
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 control-
ler circuit board.
Miswiring of remote controller
Defective transmitting receiv-
ing circuit of remote controller
Defective transmitting receiv-
ing circuit of indoor controller
board of refrigerant addresses
"0".
Noise has entered into the
transmission wire of remote
controller.
2 remote controllers are set as
"main."
(In the case of 2 remote con-
trollers)
Remote controller is connected
with 2 indoor units or more.
Repetition of refrigerant
address
Defective transmitting receiv-
ing circuit of remote controller
Defective transmitting receiv-
ing circuit of indoor controller
board
Noise has entered into trans-
mission wire of remote control-
ler.
25
Judgment and action
– Check resistance value of thermistor.
For characteristics, refer to (P1).
Check contact failure of connector (CN44) on
the indoor controller board.
Refer to "9-7. TEST POINT DIAGRAM".
Turn the power on and check restart after
inserting connector again.
Operate in test run mode and check pipe
<condenser/evaporator> temperature with
outdoor controller circuit board. If pipe
<condenser/evaporator> temperature is
extremely low (in cool mode) or high (in heat
mode), refrigerant circuit may have defect.
Operate in test run mode and check pipe
<condenser/evaporator> temperature
with outdoor control circuit board. If there
is extreme difference with actual pipe
<condenser/evaporator> temperature,
replace indoor controller board.
There is no abnormality if none of above
comes within the unit.
Turn the power off and on again to operate.
(
In the case of checking pipe temperature
with outdoor controller circuit board, be
sure to connect A-control service tool
(PAC-SK52ST).
Check disconnection or looseness of indoor
unit or transmission wire of remote controller.
Set one of the remote controllers "main" if
there is no problem with the action above.
Check wiring of remote controller.
• Total wiring length: maximum 500 m
(Do not use cable with 3 or more cores.)
• The number of connecting indoor units:
maximum 16 units
• The number of connecting remote control-
ler: maximum 2 units
If the cause of trouble is not any of
– Diagnose remote controllers.
a) When "OK" is displayed,
remote controllers 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 con-
troller board of address "0" may be abnormal.
Set a remote controller to main, and the
other to sub.
Remote controller is connected with only one
indoor unit.
The address changes to a separate setting.
– Diagnose remote controller.
a) When "OK" is displayed, remote control-
lers have no problem.
Turn the power off, and on again to check.
When becoming abnormal 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.
)
– above,