4.2 Troubleshooting the Air Compressor
Most likely problems, causes, and remedies are described below.
Causes
LCD Indication
Causes
Corrective Remedies
The DSP motor
does not start.
< P R O B L E M >
C O N N E C T I O N E R R : R E V
P r e s s R E S a f t e r C H K .
1. Power supply switch - Off
2. Power - Failed
3. Power cord - In a reversal phase
connection
4. Power cord - In a phase-lacking
connection
1. Check the main breaker.
2. Check the power supply.
3. Change 2 of 3 wires of the power
cord.
4. Reconnect the power cord tightly and
check the power supply.
NOTE: Phase-lacking is detectable only
when connecting the power.
< P R O B L E M >
C O N N E C T I O N E R R : O P E N
P r e s s R E S a f t e r C H K .
Shutdown –
1st-stage dis-
charge air tem-
perature and/ or
pressure too high
< A L A R M >
D I S . T E M P . 1 :
P r e s s R E S a f t e r C H K .
1. 2nd-stage AIR END air intake effi -
ciency - Lowered
2. Air intake fi lter - Dirty
3. Temperature of Suction Air-High
1. Contact your Hitachi distributor.
2. Clean the air intake fi lter.
3. Lower the suction air temperature.
< S H U T D O W N >
H I G H D I S . T E M P :
P r e s s R E S a f t e r C H K .
Shutdown –
2nd-stage dis-
charge air tem-
perature too high
< A L A R M >
D I S . T E M P . 2 :
P r e s s R E S a f t e r C H K .
1. Check valve – Compressed air
leaked (from the aftercooler to the
air end when the DSP unloads)
2. Suction throttle valve - Dirty
1. Replace the check valve.
2. Clean the Suction throttle valve.
Note: For information about the Suction
bypass valve, see page 29.
Shutdown –
2nd-stage suction
air temperature
too high
< S H U T D O W N >
2 N D S U C T . T E M P :
P r e s s R E S a f t e r C H K .
1. Cooling water pump – Failed, or
Cooling water pressure – Fluctuating
2. Intercooler – Dirty
1. Check the cooling water system.
2. Clean the intercooler
Shutdown –
Oil temperature
too high
< S H U T D O W N >
O I L :
H I G H T E M P
P r e s s R E S a f t e r C H K .
1. Oil cooler – Dirty
2. Room temperature – High
3. Oil temperature control valve –
Failed
1. Check the oil cooler.
2. Reduce the room temperature.
3. Check the oil temperature control
valve.
Shutdown –
Oil pressure too
low
< S H U T D O W N >
O I L :
L O W T E M P
P r e s s R E S a f t e r C H K .
1. Oil strainer and/or oil fi lter – Dirty
2. Oil level – Low
1. Clean the oil strainer
2. Replace the oil fi lter.
3. Add the oil.
Shutdown –
Main motor and/
or ancillary motor
overloading
< S H U T D O W N >
O V E R L O A D :
M A I N
P r e s s R E S a f t e r C H K .
1. Power supply voltage – Low
2. Discharge air pressure – Too high
1. Rectify the power supply voltage.
2. Check the suction throttle valve
3. Check the capacity control system.
< S H U T D O W N >
O V E R L O A D :
S U B
P r e s s R E S a f t e r C H K .
1. Power supply voltage – Low
2. Cooling fan motor – Failed
1. Rectify the power supply voltage.
2. Check the cooling fan motor.
(Measure insulation resistance etc.)
Shutdown –
Inverter tripping/
restarting
< F A I L U R E >
S Y S T E M R E T R Y :
1. Power supply voltage – Low or in unbalance
2. Discharge air pressure – Too high
3. Main motor – Overloading
NOTE:‘ INVERTER RESTART’ means that the DSP
shutdowns when the inverter repeats a
restarting action within 1 minute.
1. Rectify the power supply voltage.
2. Check the capacity control system.
3. Measure insulation resistance etc. or
check the main motor.
35
4. TROUBLESHOOTING [Troubleshooting the Air Compressor]