Low Pressure Error Or Low Pressure Sensor Anomaly - Mitsubishi Heavy Industries FDT100VNAWVH Service Manual

Error code
Indoor display
Remote control:
E49
Outdoor unit
1. Applicable model
All models
2. Error detection method
Detected by low pressure drop
and suction superheat
3. Condition of error displayed
➀ When the low pressure sensor
detects 0.079MPa or lower
for 15 seconds continuously,
compressor stops and it
restarts automatically after
3-minutes delay. And if this
anomaly occurs 5 times
within 60 minutes,
➁ 10 minutes after the
compressor starts, if the
low pressure sensor detects
0.15MPa or lower for 60
minutes continuously and
compressor suction superheat
is detected 30degC or higher
for 60 seconds continuously.
And if this anomaly occurs 5
times within 60 minutes,
➂ If low pressure sensor
detects 0.079MPa or lower
for 5 minutes continuously
(including the compressor
stop status),
4. Presumable cause
• Defective outdoor unit main
PCB
• Defective low pressure sensor
connector
• Defective low pressure sensor
• Defective suction pipe
temperature sensor
connector
• Defective suction pipe
temperature sensor
Note:
* Connect the gauge manifold to the service valve check joint during cooling, or connect it to the check joint at internal
piping of outdoor unit during heating.
RUN light
--
Green LED
control PCB
Keeps flashing
5. Troubleshooting
Check the low pressure value during
following state from the remote control
ΠCompressor is stopping
 Compressor is operating
NO
Check the insulation resistance of pressure sensor.
insulation resistance more than 100Ω
After connecting the gauge manifold on the low pressure
line, measure at the state Πabove. Compare the result
with the value indicated on the remote control.
To checking of refrigerant
amount, refrigerant circuit,
etc. (To next page)
TIMER light
Content
--
Red LED
low pressure sensor anomaly (1/2)
1-time flash
Diagnosis
Is the low
pressure sensor connection OK
(at PCB side)?
YES
During
both Œ and  state low
pressure detected at around 0MPa
without any
fluctuation.
YES
Is the
at DC500V?
YES
*
Is the
pressure difference less than
0.2MPa?
Connect the pressure sensor of
YES
spare part to outdoor unit main
PCB in the condition open to
atmosphere.
Is the pressure
0MPa displayed on the remote
control?
166
- -
'19 • PAC-SM-309
Low pressure error or
Countermeasure
Correct.
NO
Replace low pressure
NO
sensor.
NO
Defective outdoor unit
NO
main PCB ➞ Replace.
Replace low pressure
YES
sensor.