Mitsubishi Electric PCA Series Service Manual page 23

Check code Abnormal point and detection method
Condenser/evaporator temperature ther-
mistor (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,
drying, and heating operation (except
defrosting)
Short: 194°F [90:] or more
P9 Open: 40°F [ 40:] or less
Note:
When all of the following conditions are sat-
isfied, the error is not detected:
1) During cooling operation, or for 3 min-
utes after cooling operation is stopped.
2) Up to 16 minutes from 10 seconds after
cooling operation is started.
3) Outside temperature < 22°F [ 30:]
Forced compressor stop
(due to water leakage abnormality)
1 The unit has a water leakage abnormality
when the following conditions, a) and b),
are satisfied while the above-mentioned
detection is performed.
a) The intake temperature subtracted with
liquid pipe temperature detects to be
less than 14°F [ 10°C] for a total of
30 minutes. (When the drain sensor
PA
is detected to be NOT soaked in the
water, the detection record of a) and b)
will be cleared.)
b) Drain float switch detects to be in the
water for more than 15 minutes.
Note:
Once the water leakage abnormality is
detected, abnormality state will not be
released until the main power is reset.
Fan motor trouble
PB (Pb)
Remote controller transmission
error(E0)/signal receiving error(E4)
1 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)
2 Abnormal if sub remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
E0
or
1 Abnormal if indoor controller board can
E4
not receive any data normally from
remote controller board or from other
indoor controller board for 3 minutes.
(Check code: E4)
2 Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
OCH638
Cause
1 Defective thermistor
characteristics
2 Contact failure of connector
(CN44) on the indoor controller
board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Temperature of thermistor is
194°F [90:] or more or 40°F
[ 40:] or less caused by defec-
tive refrigerant circuit.
5 Defective indoor controller
board
1 Drain pump trouble
2 Drain defective
Drain pump clogging
Drain pipe clogging
3 Open circuit of float switch
4 Contact failure of float switch con-
nector
5 Dew condensation on float switch
Drain water descends along
lead wire.
Drain water is waving due to
filter clogging.
6 Extension piping connection dif-
ference at twin, triple or quadruple
system
7 Miswiring of indoor/outdoor con-
necting at twin, triple or quadruple
system
8 Room temperature thermistor/
liquid pipe temperature thermistor
detection is defective.
1 Defective fan motor
2 Defective indoor controller 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 out-
door controller circuit board.
3 Miswiring of remote controller
4 Defective transmitting receiving
circuit of remote controller
5 Defective transmitting receiving
circuit of indoor controller board
of refrigerant addresses "0".
6 Noise has entered into the
transmission wire of remote con-
troller.
23
Countermeasure
1–3 Check resistance value of thermistor.
For characteristics, refer to (P1) above.
2 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.
4 Operate in test run mode and check pipe <con-
denser/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.
5 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).
1 Check the drain pump.
2 Check whether water can be drained.
3 Check the resistance of the float switch.
4 Check the connector contact failure.
5 Check the float switch leadwire mounted.
Check the filter clogging.
6 Check the piping connection.
7 Check the indoor/outdoor connecting wires.
8 Check the room temperature display of
remote controller.
Check the indoor liquid pipe temperature
display of outdoor controller board.
12 Refer to 9-6-2. DC fan motor (fan
motor/indoor controller 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. 500 m
(Do not use cable 3 or more.)
The number of connecting indoor units:
max. 16 units
The number of connecting remote con-
troller: max. 2 units
If the cause of trouble is not in above 1–3,
4 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 control-
ler board of address "0" may be abnormal.
(