Mitsubishi Electric PLA-A12EA8 Service Manual page 22

Check code Abnormal point and detection method
Indoor/outdoor unit communication
error (Signal receiving error)
1 Abnormal if indoor controller board
cannot receive any signal normally for 6
minutes after turning the power on.
2 Abnormal if indoor controller board
cannot receive any signal normally for 3
minutes.
E6
3 Consider the unit abnormal under the fol-
lowing condition: When 2 or more indoor
units are connected to an
outdoor unit, indoor controller board
cannot receive a signal for 3 minutes
from outdoor controller circuit board, a
signal which allows outdoor controller
circuit board to transmit signals.
Indoor/outdoor unit communication
error (Transmitting error)
Abnormal if "1" receiving is detected 30
E7
times continuously though indoor controller
board has transmitted "0".
Indoor controller board
Abnormal if data cannot be read normally
FB (Fb)
from the nonvolatile memory of the indoor
controller board.
Remote controller control board
1 Abnormal if data cannot be read nor-
mally from the nonvolatile memory of the
E1
remote controller control board.
or
(Check code: E1)
E2
2 Abnormal if the clock function of remote
controller cannot be operated normally.
(Check code: E2)
Fan motor trouble
PB (Pb)
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.
PL
b) The liquid pipe temperature or the
condenser/evaporator temperature is
167°F [75°C] or more.
These detected errors will not be
cancelled until the power source is
reset.
TCH120A
Cause
1 Contact failure, short circuit or,
miswiring (converse wiring) of
indoor/outdoor unit connecting
wire
2 Defective transmitting receiving
circuit of indoor controller board
3 Defective transmitting receiving
circuit of indoor controller board
4 Noise has entered into indoor/
outdoor unit connecting wire.
1 Defective transmitting receiving
circuit of indoor controller board
2 Noise has entered into power
supply.
3 Noise has entered into outdoor
control wire.
1 Defective indoor controller
board
1 Defective remote controller
1 Defective fan motor
2 Defective indoor controller board
3 Contact failure of fan motor
connector
Abnormal operation of 4-way
valve
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
(clogging)
22
Countermeasure
Check LED display on the outdoor control
circuit board. (Connect A-control service
tool, PAC-SK52ST.)
Refer to outdoor unit service manual.
1 Check disconnection or looseness of
indoor/ outdoor unit connecting wire of
indoor unit or outdoor unit.
Check all the units in case of twin triple
indoor unit system.
2–4 Turn the power off, and on again to
check. If abnormality generates again,
replace indoor controller board or out-
door controller circuit board.
Note: Other indoor controller board may
have defect in the case of twin triple
indoor unit system.
1–3 Turn the power off, and on again to
check. If abnormality generates again,
replace indoor controller board.
1 Replace indoor controller board.
*The check cod in the parenthesis indicates
PAR-41MAA model.
1 Replace remote controller.
1-3 Refer to "9-6-2. DC fan motor (fan
motor/indoor controller circuit board".
When this error occurs, be sure to
replace the 4-way valve.
Check refrigerant pipes for disconnection
or leakage.
After the recovery of refrigerant, vacuum
dry the whole refrigerant circuit.
Refer to "9-6-2. DC fan motor (fan motor/
indoor controller circuit board".
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.