York Chiller Discharge Limiting and Low Suction Pressure Troubleshooting Guide

FORM 201.19-NM1 (204)

TROUBLESHOOTING GUIDE - CONT’D

PROBLEM	POSSIBLE	ACTION
SYS # HIGH DSCH	Poor airflow through condenser	Check for airflow restrictions caused by blockages
displayed (High discharge	coils.	on intake faces of air coils.
pressure trip)		Check for damaged fins/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	Suction superheat too high.	Check suction superheat is within range.
displayed (High discharge	Poor airflow through the condenser	Check for airflow restrictions caused by blockages
temperature)	coils.	on intake faces of air coils.
	Measured temperature incorrect.	Check discharge sensor calibration, location and
		wiring.
SYS # DSCH LIMITING	Discharge pressure unloading due	Check chilled liquid temperature is within range.
displayed (Discharge pres-	to unit operating above load limit.	Check fan operation.
sure unloading)	See also SYS # HIGH DSCH.	Check if ambient air temperature is above design
		conditions.
		Check programmed unload point.
SYS # HIGH OIL PRESS	Ball valve in oil circuit closed.	Check ball valves are open position.
DIFF is displyed. (High oil
differential pressure.)	Dirty / blocked oil filter.	Check and change oil filter cartridge.
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 LLSV is opening correctly.
	Measured pressure incorrect.	Check suction pressure transducer and wiring.
SYS # LOW CURR/MP/HP	Compressor current too low.	Check the compressor main supply voltage, fuses,
displayed		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	Check motor protector and wiring.
	failure.
	Mechanical high pressure cut-out	Check compressor discharge valve is open.
	trip.	Check cut-out and wiring.
	No motor cooling.	Check superheat.
		Check operation of economizer, TXV, and liquid
		solenoid valve.
SYS # CURR LIMITING	High compressor motor current	Check if liquid temperature is within operating limits.
displayed	has activated unloading.	Check if ambient air temperature is above operating
(Compressor current un-		limits.
loading.)

11

YORK INTERNATIONAL 201