Chilled Water Temperature Too Low With Compressor Running; Refrigerant Temperature Too Low; Leaving Chilled Water Temperature Fluctuates; Condenser Pressure Too High - Carrier 17DA Start-Up, Operation And Maintenance Instructions Manual

Chilled Water Temperature Too Low with
Compressor Running
CHILLED WATER SET POINT IN THE PLC SET TOO
LOW — Correct set point and check for overrides from the
building control system.
LOW COOLING LOAD — The compressor cannot unload
completely. If there is so little load that the guide vanes close
fully, then the water temperature will continue to drop until the
recycle function or chilled water low-temperature safety stops
the machine.
INACCURATE THERMISTOR — The reading on the pan-
el will not coincide with other sensors monitoring the leaving
chilled water.
SENSORS OUTSIDE OF THE CHILLER CONTROLS
ARE INACCURATE — The machine sensor could be correct
and other sensor(s) are out of calibration.
GUIDE VANES NOT CLOSING
• Check pressure of supply air and cushion air pressure.
• Confirm that the air signal from the transducer matches the
signal output from the PLC.
• Calibrate the positioner.
• Test the actuator for leakage past the piston seal.

Refrigerant Temperature Too Low

COOLER WATERBOX DIVISION PLATE GASKET OUT
OF PLACE — Fix gasket.
LOW REFRIGERANT CHARGE — When the machine can
be stopped, allow time for liquid to flow to the cooler. Compare
the liquid level with the charging mark on the cooler level
sightglass. Add refrigerant if required.
Check for leaks and check shutdown seal operation. Test re-
frigerant alarm sensors.

Leaving Chilled Water Temperature Fluctuates

RETURN CHILLED WATER TEMPERATURE FLUCTU-
ATING FASTER THAN CONTROLS CAN RESPOND —
Adjust controls.
CAPACITY CONTROL IN PLC NEEDS ADJUST-
ING — Adjust capacity controls.
GUIDE VANES MOVING ERRATICALLY
• Check actuator (see Guide Vanes Not Closing section
above)
• With machine not running, disconnect the actuator and
move the guide vanes manually. There should be a resis-
tance, easily overcome, at the point where the discharge dif-
fuser starts opening or closing. Check for obstructions.

Condenser Pressure Too High

LOW WATER FLOW OR HIGH WATER TEMPERA-
TURE — Check the following:
• Check condensing water pump for proper operation.
• Check delta P and delta T across the condenser water side to
determine if there is bypassing around the division plate.
• Check delta P across the condenser water pump.
• Check cooling tower controls and fans. Check to see if
tower bypass is open.
• Check for correct level in the cooling tower.
• Check flow meter readings.
• If the condenser water valves automatically regulate con-
denser flow, check the control settings and valve operation.
• Ensure that condenser water strainers are clean.
AIR IN THE CONDENSER — Air or other non-condens-
able gases in the condenser will cause a rise in normal condens-
ing pressures. Because of the subcooler, true condensing tem-
peratures cannot be determined. If the subcooler level is set ac-
cording to the method in the Charge Refrigerant section, then
the actual condensing temperature will be close to the
temperature at the subcooler inlet thermowell. This is located
adjacent to the level control/transmitter.
If air is suspected, then check the purge. See the Purge Cy-
cle section on page 19.
FOULED CONDENSER TUBES — Check for fouled or ob-
structed tubes. Clean as required.

Oil Pressure Too Low

PLUGGED FILTERS — Switch to alternate filter cartridge.
Replace plugged filter.
PRESSURE REGULATOR SET TOO LOW — Adjust
required.
FAULTY PRESSURE REGULATOR — Replace regulator.
FAULTY PUMP OR MOTOR — Replace faulty component.

Oil Pressure Too High

PRESSURE REGULATOR SET TOO HIGH — Adjust as
required.
RESTRICTION IN PRESSURE SENSING LINE —
Check pressures and temperatures throughout lubrication sys-
tem. Correct as required.

Oil Reservoir Temperature Too Low

EXCESSIVE WATER FLOWING THROUGH OIL
COOLER
• Adjust water flow.
• If equipped with an automatic regulator, adjust the
regulator.
• Check for good thermal contact between the regulator sens-
ing bulb and the oil line leaving the oil cooler. Check the
capillary tube for damage.
• Replace the regulator if faulty.

Oil Reservoir Temperature Too High

INSUFFICIENT WATER
COOLER
• Adjust water flow.
• If equipped with an automatic regulator, then adjust the
regulator.
• Check for good thermal contact between the regulator sens-
ing bulb and the oil line leaving the oil cooler. Check the
capillary tube for damage. Check for contamination plug-
ging the regulator valve.
• Replace the regulator if faulty.
FOULED OR OBSTRUCTED
TUBES — Check oil cooler. Clean if necessary.
TEMPERATURE OF OIL RETURNING FROM BEAR-
INGS TOO HIGH — Check for bearing wear, in particular
the thrust bearing. Check the bearings for foreign particles or
any indication of wiping.
A bad bearing can cause extensive damage to machine. Be
sure to diagnose and correct reasons for overheated bearings
before restarting the machine.
Compressor Discharge Gas Temperature Too
High
EXTREMELY LOW LOAD — Verify low load condition.
Add load to machine if possible.
LOW COOLER REFRIGERANT LEVEL — Insufficient
charge in the machine or condenser refrigerant level too high.
EXCESSIVE TRAVEL OF DIFFUSER THROTTLING
RING — This can only be determined through compressor
disassembly.
Safety Controls —
forms. Safety functions are programmed into the PLC which
22
FLOW THROUGH
OIL

CONTROLS

Safety controls come in multiple
as
OIL
COOLER