Haier MRV 5-RC VP1-112B Service Manual page 204

Failure code
Outdoor
Indoor unit LED status
digital
display tube:
75-0
Indoor wired
Outdoor unit LED status
controller:
4B
1. Model
MRV 5-RC series
2. Abnormity detection method
◆ Check if the difference
between high and low pressure
of system exceeds 0.4MPa after
start and before failure alarm;
◆ Check if the unit lack of
refrigerant.
◆ Check the four-way valve of
unit for normal switching and
free from backflow.
◆ Check if the detection value
of high/low pressure sensor is
correct.
◆ Check if the unit is beyond
the operation range.
3. Abnormity confirmation
conditions
75-0: Pd-Ps≤0.1Mpa within 1min
upon the INV compressor starts.
75-4: Pd-Ps≤0.4Mpa lasts for
3min.
4. Possible causes
◆ The detection value of
high/low pressure sensor is
incorrect;
◆ The refrigerant in the system
is insufficient;
◆ The four-way valve cannot
be switched normally or with
backflow.
The power module cannot
drive the compressor operating
normally;
◆ The inverter compressor is
with serious inter deterioration,
which makes it difficult to form
difference between high and
low pressure.
◆ The operation environment
is beyond the allowed range.
Normal
Diagnosis and troubleshooting
Diagnosis
Check if the high-low pressure
difference of system exceeds 0.4MPa
after start and before failure alarm;
Check if the refrigerant in the system
is with leakage or insufficient.
Check if the detection value of low
pressure sensor is correct.
If the four-way valve of outdoor unit is
with backflow and if the suction pipe
filter of compressor is blocked.
Check if it operates normally
after replacing a normal driver
module.
if the allowed operation range is exceeded.
Use the unit in accordance with
its allowed operation range.
LED5 Failure description:
Pressure difference between high and low
20 times pressure too low failure
LED1 LED2
Normal
N
Y
N
N
Y
Y
N
N
Y
N
Y
201
Troubleshooting
Replace it correctly by after-sales
personnel on site and ensure the
refrigerant is enough.
Rectify it correctly by after-sales
personnel on site.
Check if the corresponding pressure
sensor is intersected with another
compressor, especially for a double
compressor system.
Troubleshoot and replace it correctly
by after-sales personnel on site.
[Note]: Check if the suction pipe
filter of compressor is blocked, when
the discharging temperature rises
obviously.
R e p l a c e t h e d r i v e r m o d u l e
correctly.
Replace the inverter compressor
if the high-low pressure difference
cannot reach 0.4MPa above before
failure alarm.