YORK INTERNATIONAL
84
Maintenance
COMPETENT PERSONS TROUBLESHOOTING GUIDE (CONT’D)
TABLE 8 – COMPETENT PERSONS TROUBLESHOOTING GUIDE (CONT’D)
PROBLEM
POSSIBLE CAUSE
ACTION
SYS # HIGH DSCH
Poor cooling liquid flow through the
Check for restricted cooling liquid flow.
displayed
condenser.
Check for non-condensables (air) in system.
(High discharge
Excessive refrigerant charge.
Check sub-cooling is correct.
pressure trip)
Measured pressure is incorrect.
Check discharge transducer calibration and wiring.
SYS # HIGH DSCH TEMP
Suction superheat too high.
Check suction superheat is within range.
displayed (High
Measured temperature incorrect.
Check for restricted cooling liquid flow.
discharge temperature)
Check sensor calibration, location and wiring.
SYS # DSCH LIMITING
Discharge pressure unloading due
Check chilled liquid temperature is within range.
displayed
to unit operating above load limit.
(Discharge pressure
See also SYS # HIGH DSCH.
unloading)
SYS # HIGH OIL PRESS
Ball valve in oil circuit closed.
Check ball valves are in open position.
DIFF is displayed. (High
Dirty / blocked oil filter.
Check and change oil filter cartridge.
oil differential pressure)
SYS # LOW SUCTION
Badly adjusted or faulty expansion
Check superheat.
displayed
valve.
Reduced evaporator performance.
Check for restricted chilled liquid flow.
Check for fouled tube surfaces.
Check superheat.
Low refrigerant charge.
Check subcooling is correct.
Check for leaks.
Restricted refrigerant flow.
Check for blocked filter/drier.
Check YLLSV operating correctly
Measured pressure incorrect.
Check suction pressure transducer calibration and
wiring.
SYS # LOW CURR/
Compressor current too low.
Check compressor mains supply, fuses, contactors
MP/HP displayed
and wiring. Check mains supply voltage is within
tolerance.
Measured current is incorrect.
Check for defective current transformer (resistance
should be between 42 and 44 Ohms).
Check calibration resistor is correctly fitted.
Compressor motor protector
Check motor protector and wiring.
signal failure.
Check compressor motor.
Mechanical high pressure
Check compressor discharge valve is open.
cutout trip.
Check cutout setting and wiring.
No motor cooling.
Check motor cooling service valve is open.
Check operation of motor cooling, TEVs and liquid
solenoid valve.
SYS # CURR LIMITING
High compressor motor current
Check liquid temperature is within operating limits.
displayed
has activated unloading.
Check if ambient air temperature is above unloading).
(Compressor current
operating limits.
Summary of Contents for YCWS0313SC
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