Mitsubishi Electric SLZ Series Technical & Service Manual page 17

Check code Abnormal point and detection method
Pipe temperature thermistor/Condenser /
Evaporator (TH5)
1 The unit is in 3-minute resume protec-
tion 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.)
2 Constantly detected during cooling, dry-
ing, and heating operation (except defrost-
ing)
Short: 194°F [90°C] or more
Open: -40°F [-40°C] or less
P9
Abnormal refrigerant circuit
During Cooling, Drying, or Auto Cooling
operation, the following conditions are
regarded as failures when detected for 1
second.
a) The compressor continues to run for 30 or
more seconds.
b) The liquid pipe temperature (TH2) or the
PL condenser/evaporator temperature (TH5)
is 167°F [75°C] or more.
These detected errors will not be
cancelled until the power source is
reset.
Remote controller transmission error(E0)/
signal receiving error(E4)
1 Abnormal if main or sub remote controller
cannot receive any transmission normally
from indoor unit of refrigerant address "0"
for 3 minutes.
(Check code : E0)
2 Abnormal if sub-remote controller could
not receive for any signal for 2 minutes.
(Check code: E0)
E0
or
1 Abnormal if indoor controller board cannot
E4
receive normally any data from remote
(6831
controller board or from other indoor con-
or
troller board for 3 minutes. (Check code:
6834)
E4)
2 Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
TCH118
Cause
1 Defective thermistor
characteristics
2 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
194°F [90°C] or more or
-40°F [-40°C] or less caused by
defective refrigerant circuit.
Defective indoor controller board
1 Abnormal operation of 4-way
valve
2 Disconnection of or leakage in
refrigerant pipes
Air into refrigerant piping
Abnormal operation (no rotation)
of indoor fan
· Defective fan motor
· Defective indoor control board
Defective refrigerant circuit
(restriction)
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.
Miswiring of remote controller
Defective transmitting/receiving
circuit of remote controller
Defective transmitting/receiving
circuit of indoor controller board
of refrigerant address "0"
Noise has entered into the
transmission wire of remote
controller.
17
*1: only P-series outdoor unit
Countermeasure
1– Check resistance value of thermistor.
For characteristics, refer to (P1).
2 Check contact failure of connector (CN44) on
the indoor controller board.
Refer "8-5. 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 the above
comes within the unit.
Turn the power off and on again to operate.
( *1
In case of checking pipe temperature
with outdoor controller circuit board, be
sure to connect A-control service tool
(PAC-SK52ST).
1 When this error occurs, be sure to replace
the 4-way valve.
2 Check refrigerant pipes for disconnection or
leakage.
3 After the recovery of refrigerant, vacuum dry
the whole refrigerant circuit.
4 Refer to section "8-7. TROUBLESHOOTING
OF MAIN PARTS".
5 Check refrigerant circuit for operation.
To avoid entry of moisture or air into
refrigerant circuit which could cause
abnormal high pressure, purge air in
refrigerant circuit or replace refrigerant.
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. 500 m
(Do not use cable of 3 wire or more)
• The number of connecting indoor units: max.
16 units
• The number of connecting remote controller:
max. 2 units
If the cause of trouble is not in above 1–3,
Diagnose remote controllers.
a) When "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 "NG" is displayed, replace remote
controller.
c) When "E3" or "ERC" is displayed, noise may
be causing abnormality.
)