Mitsubishi Electric PL18FK2 Service And Parts Manual page 77

Check
code
P5
P6
P7
P8
Diagnosis of malfunction
Malfunction of drain
Pump
Coil frost protection
has worked.
System error
Signal transmission error
In twinttriple control, the
first unit has not received
signal from the second
unit or the third unit for 5
minutes.
Abnormality of outdoor
unit
Indoor board does not
see drop in indoor coil
temperature during call
for compressor
operation
Cause
1) Malfunction of drain pump
2) Damaged drain sensor
1)Short cycle of air cycle
2) Dirty air filter
3) Damaged fan
4) Abnormal refrigerant
1) Wrong address-setting
2) Signal transmittinglreceiving
circuit of remote controller is
abnormal.
3) Wrong SW6-setting
1) Bad contact of transmission
wire
2) Wrong operation due to infra-
red signal from other
appliances
If outdoor unit does not
function:
1) Wrong wiring of indoorlout-
door connecting wire
2) Reversed control wires.
3) Protection device has worked
If outdoor unit functions
properly:
1) Damaged indoor pipe
thermistor
Check points
- - -
1) Check the drain pump.
2) Check the drain sensor.
0
Check the drain sensor heater. If normal, its
resistance should be 82 0.
If normal, replace the indoor controller board.
1) Clear the obstruction form the air cycle
2) Clean the air filter.
3) Check the fan.
4) Check the refrigerant temperature
1) Check the address-setting.
2) Check with another remote controller. If check
code other than "Pi"' appears, replace the
former remote controller.
3) Check SW6 setting
1) Check the transmission wire
2) Short-circuit between
O
and Q of CN40 and
attach CN40 to the following unit.
0
Second unit in twin control
0
Second and third units in triple control
0
Sub units in group control
1) Check the indoorloutdoor connecting wire.
2) Check the protection devices.
3) Measure the resistance of the indoor pipe
temperature thermistor.
4) Check for 12VDC between control wires 1 &
2 at the outdoor unit during a call for cooling
(P8 code must be reset).
a
If 12VDC is present check the wiring inside
the outdoor unit, transformer secondaries and
control fuse, if all OK, change outdoor board.
0
If 12VDC is not present check same wires at
indoor unit.
-
If 12VDC is present at the indoor, locate and
repair the broken control wire.