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Troubleshooting
COMPETENT PERSONS TROUBLESHOOTING GUIDE
PROBLEM
No display on panel -
unit will not start
NO RUN PERM displayed
(No run permissive)
SYS # HIGH OIL TEMP
coils.
Chiller FAULT: LOW
AMBIENT TEMP displayed
Chiller FAULT: HIGH
AMBIENT TEMP displayed
Chiller FAULT: LOW
WATER TEMP displayed
Chiller FAULT: VAC
UNDERVOLTAGE
displayed.
176
POSSIBLE CAUSE
Mains supply to control system OFF.
Emergency stop device off.
Under voltage relay tripped.
No supply to - T2.
No 24VAC supply to power board.
No +12V output from powerboard.
No liquid flow through the cooler.
Flow switch contacts are not made.
Poor airflow through the condenser
Measured temperature incorrect.
Ambient air temperature is lower
than the programmed operating
limit.
Measured temperature is incorrect.
Ambient air temperature is higher
than the programmed operating limit.
Resid. heat is not being dissipated.
Measured temperature is incorrect.
Leaving liquid drops below the
programmed low limit faster than the
unit can unload.
Unit is not unloading.
Measured temperature is incorrect.
Poor mains supply voltage.
ACTION
POSSIBLE CAUSE
Switch on main supply if safe to do so.
Check if control panel emergency stop switch
and any remote emergency stop devices are in
the OFF position. Turn to ON position (1) if safe
to do so.
Check mains supply.
Check emergency stop switch fuses.
Check wiring from - T2 to powerboard and fuse.
Replace powerboard or isolate excessive load on
the board.
Ensure that liquid pumps are running. Valves are
correctly set and flow is established.
Check that the flow switch is functional and is
installed according to the manufacturer's instructions.
Note: On some systems the pump starter may be wired
to the unit and controlled to start by the unit.
Check for airflow restrictions caused by blockages on
intake faces of air coils.
Check sensor calibration, location and wiring.
Use the 'ambient temp.' key to display the
temperature and confirm that the displayed value is
approximately correct. The warning message should
clear when the ambient air temperature rises above
the programmed operating limit.
Check the programmed settings are correct for the
options fitted to the unit.
Check sensor calibration, location and wiring.
Use the 'ambient temp.' key to display the
temperature and confirm that the displayed value is
approximately correct. The warning message should
clear when the ambient air temperature falls below
the programmed operating limit.
Check that the programmed settings are correct for
the options fitted to the unit.
Check fan is operating correctly and the rotation is
correct. Check for airflow recirculation.
Check sensor calibration, location and wiring.
Check for restrictions in the liquid flow line.
Check that the liquid flow is stable.
Check the supply to the unloader valve solenoid.
Check that the compressor unloads correctly.
Check sensor calibration, location and wiring.
Check mains supply is stable and within allowable
limits.
Check for voltage dip on compressor start.
ACTION
JOHNSON CONTROLS
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