Mitsubishi Electric MR. SLIM PCA Series Service Manual page 31

Abnormal point and detection method
Check code
Pipe temperature thermistor/
Condenser-Evaporator (TH5)
The unit is in 3-minute resume protection
mode if short/open of thermistor is
detected. Abnormal if the unit does not
get back to normal within 3 minutes. (The
unit returns to normal operation, if it has
been reset normally.)
Constantly detected during cooling,
drying, and heating operation (except
defrosting)
Short: 90˚C or more
Open: −40˚C or less
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
E0
cannot receive any data normally from
or
remote controller board or from other
E4
indoor controller board for 3 minutes.
(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 sec-
onds and could not transmit.
(Check code: E3)
Remote controller receives transmitted
data at the same time and compares the
received and transmitted data. Abnormal
if these data are judged to be different
E3
30 continuous times. (Check code: E3)
or
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)
OCH659A
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 controller
circuit board.
Miswiring of remote controller
Defective transmitting receiving
circuit of remote controller
Defective transmitting receiving
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 case of 2 remote controllers)
Remote controller is connected
with 2 indoor units or more.
Repetition of refrigerant
address
Defective transmitting receiving
circuit of remote controller
Defective transmitting receiving
circuit of indoor controller board
Noise has entered into transmis-
sion wire of remote controller.
31
Countermeasure
– 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 cooling mode) or high (in
heating 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 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 "RC OK" is displayed,
Remote controllers have no problem.
Turn the power off, and on again to check.
If abnormality generates again, replace
indoor controller board.
b) When "RC NG" is displayed,
Replace remote controller.
c) When "RC E3" or "ERC 00-66" 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 "RC OK" is displayed, remote con-
trollers have no problem.
Turn the power off,and on again to check.
When becoming abnormal again, 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 abnormal-
ity.
)
– above,