Mitsubishi Electric PKH18FK Technical & Service Manual page 53

Check
Diagnosis of malfunction
code
Signal transmitting/receiving
EO
error
(Indoor controller does not
respond to remote controller
signal.)
Abnormality of room temper-
P1
ature thermistor (RT1)
Abnormality of indoor coil
P2
thermistor (RT2)
Signal transmission error
P3
(Remote controller does not
respond to indoor controller
signal.)
Abnormality of drain sensor
P4
Malfunction of drain pump
P5
Coil frost protection is work-
P6
ing.
P7
System error
Abnormality in outdoor unit
P8
Cause
During individual unit control
1) Bad contact of transmission
wire
2) Signal transmitting/receiving cir-
cuit is abnormal.
1) Bad contact of thermistor
2) Damaged thermistor
1) Bad contact of transmission
wire
2) Signal transmitting/receiving cir-
cuit is abnormal.
3) Wrong operation due to noise
wave emitted by other appli-
ances
1) Bad contact of transmission
wire
2) Damaged thermistor
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 transmitting/receiving cir-
cuit of remote controller is
abnormal.
3) Wrong SW6-setting
1) Wrong wiring of indoor/outdoor
connecting wire
2) Reversed phase
3) Protection device is working
4) Damaged outdoor coil thermis-
tor
Check points
1) Check the transmission wire.
2) Check with another remote controller. If "EO" is
still indicated, replace the indoor controller
board.
If other check code appears. replace the origi-
nal remote controller.
1) Check the thermistor.
2) Measure the resistance of the thermistor.
Normal resistance should be as follows.
32˚F····15kΩ 86˚F ···4.3kΩ
50˚F······9.6kΩ 104˚F ···3.0kΩ
68˚F······6.3kΩ
If the resistance is normal, replace the indoor
controller board.
1) Check the transmission wire.
2) Check with another remote controller.
If "P3" is still indicated, replace the indoor
board.
If other check code appears, replace the origi-
nal remote controller.
3) Short-circuit between 1 and 2 of CN40 and
attach CN40 to the following units.
Second unit in twin control
Second and third units in triple control
Sub units in group control
1) Check the connector.
2) Measure the resistance of the thermistor 4 - 5.
As for the normal resistance, refer to the case
of P1.
If the resistance is normal, replace the indoor con-
troller board.
1) Check the drain pump.
2) Check the drain sensor.
Check the drain sensor heater. Normal resis-
tance should be 82Ω.
If the resistance is normal, replace the indoor con-
troller board.
1) Clear obstructions from the air cycle.
2) Clean the air filter
3) Check the fan.
4) Check the refrigerant temperature and pres-
sure.
1) Check the address-setting.
2) Check with another remote controller. If check
code other than "P7" appears, replace the origi-
nal remote controller.
3) Check SW6 setting.
1) Check the indoor/outdoor connecting wire.
2) Change the connection of electric wiring.
3) Check the protection device.
4) Measure the resistance of the outdoor coil ther-
mistor. If the resistance is normal, replace the
outdoor controller board.
53