York YCAS0295EB, Installation Operation & Maintenance

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191 YORK INTERNATIONAL
FORM 201.19-NM7 (804)
TROUBLESHOOTING GUIDE - CONT’D
11
PROBLEM POSSIBLE ACTION
SYS # HIGH DSCH
displayed (High discharge
pressure trip) Poor air ß ow through condenser
coils.
Check for air ß ow restrictions caused by blockages
on intake faces of air coils.
Check for damaged
Þ ns/return bends.
Check for correct fan operation and direction of
rotation.
Check for non-condensables (air) in system.
Excessive refrigerant charge. Check that the sub-cooling is correct.
Measured pressure is incorrect. Check discharge transducer and wiring.
SYS # HIGH DSCH TEMP
displayed (High discharge
temperature) Suction superheat too high. Check suction superheat is within range.
Poor air ß ow through the condenser
coils.
Check for air ß ow restrictions caused by blockages
on intake faces of air coils.
Measured temperature incorrect. Check discharge sensor calibration, location and
wiring.
SYS # DSCH LIMITING
displayed (Discharge pres-
sure unloading) Discharge pressure unloading due
to unit operating above load limit.
See also SYS # HIGH DSCH. Check chilled liquid temperature is within range.
Check fan operation.
Check if ambient air temperature is above design
conditions.
Check programmed unload point.
SYS # HIGH OIL PRESS
DIFF is displyed. (High oil
differential pressure.) Ball valve in oil circuit closed.
Dirty / blocked oil Þ lter.
Check ball valves are open position.
Check and change oil Þ lter cartridge.
SYS # LOW SUCTION
displayed Badly adjusted or faulty expansion
valve. Check superheat.
Reduced evaporator performance. Check for restricted chilled liquid ß ow.
Check for fouled tube surfaces.
Check superheat.
Low refrigerant charge. Check subcooling is correct.
Check for leaks.
Restricted refrigerant ß ow. Check for blocked Þ lter / drier.
Check LLSV is opening correctly.
Measured pressure incorrect. Check suction pressure transducer and wiring.
SYS # LOW CURR/MP/HP
displayed Compressor current too low. Check the compressor main supply voltage, fuses,
contactors and wiring. Check main supply voltage is
within tolerance. Check 2ACE MP fault code.
Measured current is incorrect. Check for defective Motor Protector Module.
Compressor motor protector signal
failure. Check motor protector and wiring.
Mechanical high pressure cut-out
trip. Check compressor discharge valve is open.
Check cut-out and wiring.
No motor cooling. Check superheat.
Check operation of economizer, TXV, and liquid
solenoid valve.
SYS # CURR LIMITING
displayed
(Compressor current un-
loading.) High compressor motor current
has activated unloading. Check if liquid temperature is within operating limits.
Check if ambient air temperature is above operating
limits.