Error Display E55; Error Display E57; Defective Under-Doom Thermistor; Insufficient Refrigerant Volume - Mitsubishi Heavy Industries FDCA Series Technical Manual

e55
Error display :
15
Indoor unit
Red LED
Green LED Keeps flashing
Is the
under-doom
thermistor connector
connection OK?
NO
Repair
● Display conditions
If the temperature sensed by the thermistor is –50ºC or lower continuously for 5 seconds between
10 minutes and 10 minutes 20 seconds after the compressor goes ON, the compressor stops. After
a 3 minute delay, the compressor restarts. If this state is detected 3 times in 40 minutes.
e57
Error display :
16
Indoor unit
Red LED
Green LED Keeps flashing
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.)
[Defective under-doom thermistor] (Only case of FDCA801, 1001 type)
Stays OFF Red LED
Green LED
YES

[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 81) is implemented
3 times within 30 minutes.
Outdoor unit
1 time flash
Keeps flashing
Are the under-doom
thermistor characteristks OK,
is there no broken wire?
NO
Defective under-doom
thermistor Replacement
Outdoor unit
1 time flash
Keeps flashing
153
- -
Defective outdoor unit control
PCB Replacement (Defective
under-doom thermistor input circuit)
Under-doom thermistor (Th
Resistance temperature characterisics
15
YES
10
5
0 10
Temperature (°C)
Return air thermistor (Th
Indoor unit heat exchanger thermistor
(Th -R1, R2)
I
Resistance temperature characterisics
15
10
5
0 10
Temperature (°C)
-H)
O
5kΩ at 25°C
20 30 40 50
-A)
I
5kΩ at 25°C
20 30 40 50