Mitsubishi Electric PCA-A24KA Service Manual page 19

Abnormal point and detection method
Error Code
Pipe temperature thermistor/
Condenser-Evaporator (TH5)
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.)
Constantly detected during cooling,
drying, and heating operation (except
defrosting)
P9
Forced compressor stop
(due to water leakage abnormality)
The unit has a water leakage abnor-
mality 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 -10
30 minutes. (When the drain sensor
PA is detected to be NOT soaked in the
water, the detection record of a) and b)
(2500)
will be cleared.)
b) Drain float switch detects to be in the
water for more than 15 minutes.
*Once the water leakage abnormality is
detected, abnormality state will not be
released until the main power is reset.
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.
(Error code : E0)
Abnormal if sub remote controller could
not receive for any signal for 2 minutes.
(Error code: E0)
Abnormal if indoor controller board
cannot receive any data normally from
remote controller board or from other
E0
indoor controller board for 3 minutes.
or
(Error code: E4)
E4
Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Error code: E4)
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
defective refrigerant circuit.
Defective indoor controller
board
Drain pump trouble
Drain defective
· Drain pump clogging
· Drain pipe clogging
Open circuit of float switch
Contact failure of float switch
connector
Dew condensation on float switch
[14 ·Drain water descends along
lead wire.
·Drain water waving due to filter
clogging.
Extension piping connection
difference at twin, triple, quad-
ruple system.
Miswiring of indoor/outdoor
connecting at twin, triple, quad-
ruple system.
Room temperature thermistor/
liquid pipe temperature thermis-
tor detection is defective.
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.
19
Cause
– Check resistance value of thermistor.
For characteristics, refer to (P1) above.
Check contact failure of connector (CN44) on
the indoor controller board. Refer to 9-7.
Turn the power on and check restart after
inserting connector again.
Operate in test run mode and check pipe <con-
denser/evaporator> temperature with outdoor
controller circuit board. If pipe
<condenser/evaporator> temperature is exclu-
sively low (in cooling mode) or high (in heating
mode), refrigerant circuit may have defect.
Operate in test run mode and check pipe <con-
denser/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 the drain pump.
Check whether water can be drained.
Check the resistance of the float switch.
Check the connector contact failure.
Check the float switch leadwire mounted.
Check the filter clogging.
Check the piping connection.
Check the indoor/outdoor connecting wires.
Check the room temperature display of
remote controller.
Check the indoor liquid pipe temperature dis-
play of outdoor controller board.
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.
(Do not use cable
• The number of connecting indoor units:
max. 16 units
• The number of connecting remote control-
ler: max. 2 units
When the above-mentioned problem of
are not applied,
Diagnose remote controllers.
a) When "RC OK" is displayed, remote con-
trollers 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 00-06" is dis-
played, noise may be causing abnormality.
If the unit is not normal after replacing
indoor controller board in group control,
indoor controller board of address "0"
may be abnormal.
Countermeasure
)
3 or more.)
~