York YCAS0130 Installation, Operation & Maintenance Manual page 201

PROBLEM
SYS # HIGH DSCH
displayed (High discharge
pressure trip)
SYS # HIGH DSCH TEMP
displayed (High discharge
temperature)
SYS # DSCH LIMITING
displayed (Discharge pres-
sure unloading)
SYS # HIGH OIL PRESS
DIFF is displyed. (High oil
differential pressure.)
SYS # LOW SUCTION
displayed
SYS # LOW CURR/MP/HP
displayed
SYS # CURR LIMITING
displayed
(Compressor current un-
loading.)
YORK INTERNATIONAL
TROUBLESHOOTING GUIDE - CONT'D
POSSIBLE
Poor airfl ow through condenser
coils.
Excessive refrigerant charge.
Measured pressure is incorrect.
Suction superheat too high.
Poor airfl ow through the condenser
coils.
Measured temperature incorrect.
Discharge pressure unloading due
to unit operating above load limit.
See also SYS # HIGH DSCH.
Ball valve in oil circuit closed.
Dirty / blocked oil fi lter.
Badly adjusted or faulty expansion
valve.
Reduced evaporator performance.
Low refrigerant charge.
Restricted refrigerant fl ow.
Measured pressure incorrect.
Compressor current too low.
Measured current is incorrect.
Compressor motor protector signal
failure.
Mechanical high pressure cut-out
trip.
No motor cooling.
High compressor motor current
has activated unloading.
ACTION
Check for airfl ow restrictions caused by blockages
on intake faces of air coils.
Check for damaged fi ns/return bends.
Check for correct fan operation and direction of
rotation.
Check for non-condensables (air) in system.
Check that the sub-cooling is correct.
Check discharge transducer and wiring.
Check suction superheat is within range.
Check for airfl ow restrictions caused by blockages
on intake faces of air coils.
Check discharge sensor calibration, location and
wiring.
Check chilled liquid temperature is within range.
Check fan operation.
Check if ambient air temperature is above design
conditions.
Check programmed unload point.
Check ball valves are open position.
Check and change oil fi lter cartridge.
Check superheat.
Check for restricted chilled liquid fl ow.
Check for fouled tube surfaces.
Check superheat.
Check subcooling is correct.
Check for leaks.
Check for blocked fi lter / drier.
Check LLSV is opening correctly.
Check suction pressure transducer and wiring.
Check the compressor main supply voltage, fuses,
contactors and wiring. Check main supply voltage is
within tolerance. Check 2ACE MP fault code.
Check for defective Motor Protector Module.
Check motor protector and wiring.
Check compressor discharge valve is open.
Check cut-out and wiring.
Check superheat.
Check operation of economizer, TXV, and liquid
solenoid valve.
Check if liquid temperature is within operating limits.
Check if ambient air temperature is above operating
limits.
FORM 201.19-NM1 (204)
11
201