Anomalous Low Pressure Or Low Pressure Sensor Disconnection - Mitsubishi Heavy Industries FDTCVA SERIES Technical Manual

Error display :
15
Indoor unit
Red LED
Green LED Keeps flashing
Is there any gap between actual
pressure and sensed pressure by
the microcomputer?
YES
Are the low pressure sensor
connector connected
properly(sensor side, PCB side)?
YES
Is the amount of the refrigerant proper?
Is there any irregularity on the
refrigerant circuit?
• Display Conditions
The compressor is stopped when the low pressure becomes
0.079 MPa or lower for 15 seconds continuously, or when it
becomes 0.15 MPa or lower and the superheat becomes 30K or
bigger for 1 minute. The compressor will restart automatically
after 3-minute delay.
The error occurs when the situation happens 3 times within 60
minutes, or the low pressure stays 0.079 MPa or lower for 5
minutes continuously.
Is the service
valve fully open?
pressure sensor – suction pipe
temperature thermistor connector
connected properly?
pressure sensor – suction pipe
temperature thermistor
characteristics OK?
Is the low pressure during
operation normal?
Outdoor control PCB is faulty
(Low pressure sensor – suction pipe temperature
thermistor input circuit is faulty.)
E49

[Anomalous low pressure or low pressure sensor disconnection.]

[Only case of 302 ~ 1002 models]
Stays OFF Red LED
Green LED
NO
NO
Replace the outdoor
unit control PCB.
NO
YES
Are the low
NO
YES
Are the low
NO
YES
NO
YES
Replace it
Outdoor unit
1 time flash
Keeps flashing
NO
·
Set low pressure for protective control
Open it fully.
Correct it
Low pressure sensor – suction pipe
temperature thermistor is faulty Replace it
Charge with refrigerant.
281
- -
Correct it
Replace the low
pressure sensor
Does the error resolved?
Compressor
operation
Compressor
stop
0.079 0.227
Low pressure (MPa)