Power Transistor Thermistor Faulty; Insufficient Refrigerant Volume - Mitsubishi Heavy Industries R410A Service Manual

e56
Error display :
15
Indoor unit
Red LED
Green LED Keeps flashing
Is the
power transistor thermistor
connector connection
OK?
NO
Repair
● Display conditions
If the temperature sensed by the thermistor is –10ºC or lower con-
tinuously for 5 seconds between 10 minutes and 10 minutes 20
seconds after the compressor goes ON, the compressor stops. Af-
ter a 3 minute delay, the compressor restarts. If this state is de-
tected 3 times in 40 minutes.
e57
Error display :
16
Indoor unit
Red LED
Green LED Keeps flashing
Note (1) The green LED in the outdoor unit is used in the FDCA301 ~ 601 models only.
Is the service valve
opened fully?
YES
Are the
connections of the connectors
to the indoor heat exchanger and return
air thermistor OK?
YES
Are the
characteristics of the indoor
heat exchanger and return air
thermistor OK?
YES
Is the low pressure during
operation normal?
YES
Indoor control PCB faulty
Replace
(The indoor heat exchanger
and return air thermistor input
circuits are faulty.)
[Power transistor thermistor faulty.] (Only case of 151~251 type)
Stays OFF Red LED
Are the
power transistor
YES
thermistor characteristics
OK, is there no
broken wire?
Defective power transistor
thermistor

[Insufficient refrigerant volume.]

Stays OFF Red LED
Green LED
NO
Fully opened.
NO
Normal
NO Indoor heat exchanger and
return air thermistor faulty
Replace
NO
Charge with refrigerant.
● Display conditions
If insufficient refrigerant protection (See page 92) is implemented
3 times within 30 minutes.
Outdoor unit
1 time flash
YES
NO
Replacement
Outdoor unit
1 time flash
Keeps flashing
- 32 -
Defective outdoor unit control
PCB Replacement (Defective
power transistor thermistor input
circuit)
Temperature-resistance
characteristics of power
transistor thermistor (Th
100
T < 80°C
50
0
0 20 50 80
Temperature [T] (°C)
Return air thermistor (Th
Indoor unit heat exchanger thermistor
(Th -R1, R2)
I
Resistance temperature characterisics
15
10
5
0 10
D)
O-
10
T > 80°C
5
0
100 120
-A)
I
5kΩ at 25°C
20 30 40 50
Temperature (°C)