Activation Of High Pressure Increase Protection Device - Hitachi RAS-(3-6)HVNC1(E) Service Manual

8 Troubleshooting
45
Alarm code
- When the compressor is operated with the discharge pressure (Pd) higher than 3.8MPa for 1 minute, the retry
operation is performed 3 minutes after all compressors are stopped. Thereafter, this alarm code is indicated when
above abnormality is detected twice in 30 minutes.
Is there a leakage of the
solenoid valves (SVA)?
Is the outdoor unit stop valve
Are expansion valves fully
Are electric wiring and
refrigerant piping connections
between the indoor and outdoor
unit incorrectly connected?
Check if indoor or outdoor intake air
temperature is too high
Phenomenon
Leakage of solenoid valve (SVA)
Abnormal high pressure sensor
Excessively
high discharge
pressure
Excessively high temperature of
inlet air for outdoor unit or indoor
Incorrect connection between
Locked expansion valve with fully
258
SMGB0087 rev.0 - 12/2013

Activation of high pressure increase protection device

No
closed?
No
Is the high-pressure
sensor normal?
Yes
closed and locked?
No
Check the outdoor electronic expansion valve during cooling
and the indoor electronic expansion valve during heating.
No
Cause
Closed stop valve
unit
indoor unit and outdoor unit
closed
Yes
Replace the solenoid valve
Yes
Open the stop valve
No
Check connection of the OU
PCB1. Replace the high-
pressure sensor if faulty
Check OU PCB1 or
Yes
connection of OU PCB1.
Replace the electronic
expansion valves if faulty
Yes
Correctly connect it
Check item
Check the outlet
temperature of solenoid
valve (SVA)
Check stop valve
Check connecting
condition and output
voltage "CN100" (on
OU PCB1) for high
pressure sensor
Check thermistor for
indoor unit and outdoor
unit inlet air tempera-
ture
Check electrical
system and refrigerant
cycle system
Check condition of
connector "CN100" on
OU PCB1
(SVA) if faulty
Action
(Turn OFF the main switch)
Check connection. Replace
solenoid valve (SVA) if faulty
Open stop valve
Replace high pressure
sensor if faulty
Replace the inlet air
thermistor if faulty
Correctly connect
Repair connector for OU PCB1
or expansion valve. Replace
if faulty