Technical data

8 TROUBLE SHOOTING
8.1 General Requirements
Units are not generally user serviceable and no attempt
should be made to rectify any faults found with the unit
unless suitably qualified and equipped to do so. If in any
doubt, contact your local York Agent. To avoid personal
injury or possible damage to the unit, the trouble
shooting information given in the following section must
only be used by competent service personnel using
correct procedures and equipment.
8.2 Trouble Shooting
In any case where the control centre detects conditions
or control functions requiring the unit to stop, it will shut
down the unit and display the reason for the shutdown.
Most shutdowns will be due to normal cycling of the unit
due to lack of load, scheduled off cycles etc., but others
may be caused by an internal or external fault detected
by the control centre. For a full description of the
operation of each of these shutdown functions refer to
the control centre Operation Instruction.
In the case of shutdowns caused by cycling contacts, or
by other conditions unlikely to cause an ongoing
problem, the control centre will automatically restart the
unit as soon as the contacts or conditions allow the unit
to run. If, however, this type shutdown occurs
unexpectedly or repeatedly, a problem may exist which
requires attention.
For shutdowns caused by conditions which may lead to
damage to the unit, the control centre will require a
manual reset before allowing a restart. In this situation it
is essential to determine the exact cause of the
shutdown and rectify the problem before putting the unit
back into service.
Some operating conditions are not monitored by the
control centre such as compressor wear, oil condition,
water treatment levels, etc. Detection of any potential
problems caused by these conditions relies on daily
monitoring of the unit and by regular service inspections
- see Sections 6 & 7.
The possible causes and recommended actions listed in
these tables should be used for guidance only and
should not be considered exhaustive.
035L02381-GB0 8-1
Control Centre Initiated Shutdowns - Automatic Restart
Displayed Reason for
Shutdown
Control Function Possible Cause Recommended Action
LOW WATER TEMP
Leaving chilled liquid more
than 2.2 °C below setpoint
Load on system less than
min. capacity
Check water temperature
differential is as expected
Temperature sensor fault Check sensor operation
and wiring
SLIDE VALVE ABOVE
10%
Start attempt while slide
valve is at greater than
10% load position
Slide valve not unloading Check slide valve operation
INTERNAL CLOCK
Programmed Daily
Schedule in shutdown
period
Incorrect programming Check programmed Daily
Schedule is correct
MULTI UNIT CYCLING
Multi-Unit cycling device
contacts closed
Incorrect use of contacts Check correct operation of
Multi-Unit cycling device
SYSTEM CYCLING
Remote/Local cycling
device contacts closed
Incorrect use of contacts Check correct operation of
remote cycling device