York YVAA Installation Operation & Maintenance page 179

Form 201.47-ICOM1
Issue date: 17/11/2022
Table 32 - Troubleshooting guide (cont'd)
Problem
System fault:
High discharge pressure
System fault:
High discharge temperature
System fault:
High motor temperature
System fault:
Low suction pressure
System fault:
Discharge pressure limiting
System fault:
Low economizer superheat
Note: Always remove power to the chiller and ensure the DC Bus voltage has bled off.
JOHNSON CONTROLS
Possible cause
Coils dirty.
Coils are damaged.
Fans NOT operating.
System is overcharged.
Discharge Temperature Sensor is defective.
Condenser Fans NOT operating or are run-
ning backwards.
Coils dirty.
High Superheat.
High Motor temperature input from one of the
sensors.
Low charge.
Transducer reads incorrectly.
Suction Temp. Sensor reads incorrectly.
Low flow.
Condenser Drain Valve NOT operating.
Condenser or Drain Valve defective.
Discharge Transducer is defective.
Ambient Temp. very high.
Fans not operating.
Remote or local discharge pressure
load limiting is programmed.
Economizer line temperature sensor is
defective
Economizer transducer is defective
Economizer feed valve malfunction
Economizer line solenoid purge valve mal-
function
SECTION 9 - MAINTENANCE
Action
Check and clean coils.
Comb out fins.
Check fan fuses.
Check fan rotation.
Check fan motor/blade.
Remove charge and check subcooling.
Check Sensor.
Check Fans.
Check and clean Coils.
Measure Superheat with gauges and
thermocouple. Determine cause.
Refrigerant charge low. Check subcooling.
Excess charge in system, High discharge
pressure. Check subcooling.
High Superheat. Drain/Feed Valves NOT
controlling. Isolate cause.
Motor Sensor reading incorrectly. Program
panel to ignore a single sensor.
Economizer Solenoid energized at low
speeds. Valve is leaking through.
Check subcooling.
Check transducer against a gauge.
Check sensor against a thermocouple.
Check flow.
Check Drain Valve operation.
Check superheat.
Check Drain Valve operation.
Check superheat.
Check transducer against a gauge.
Normal operation.
Check fan operation.
Normal operation.
Check temperature sensor
Check transducer against a gauge
Check economizer feed valve operation
Check economizer line solenoid purge
valve operation
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