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SECTION 9 - MAINTENANCE
Table 26 - 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
Note: Always remove power to the chiller and ensure the DC Bus voltage has bled off.
172
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 (Flash Tank Feed) Valve
NOT operating.
Condenser or Drain (Flash Tank Feed) Valve
defective.
Discharge Transducer is defective.
Ambient Temp. very high.
Fans not operating.
Remote or local discharge pressure
load limiting is programmed.
Form 201.28-NM1.1
Issue date: 08/06/2021
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 Feed and Drain Valve operation.
Check superheat.
Check Feed and Drain Valve operation.
Check superheat.
Check transducer against a gauge.
Normal operation.
Check fan operation.
Normal operation.
JOHNSON CONTROLS
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