Quantech QWC4, Installation Operation & Maintenance, Page: 148 / 156

QUANTECH
148
FORM QWC4-NM1 (221)
ISSUE DATE: 02/28/2021
SECTION 8 - TROUBLESHOOTING
TABLE 45 - TROUBLESHOOTING GUIDE
PROBLEM POSSIBLE CAUSE ACTION
No Display on Control Panel.
Unit Will NOT Run
Electric supply to the panel is missing.
High voltage to the chiller is missing.
Check 1FU, 2FU, 3FU, 4FU, 5FU, 14FU,
15FU, 17FU, or 19FU.
Check 2T or 10T Transformer.
Line fuse is blown. Check fuses.
Control board is defective. Replace control board.
Display board is defective. Replace display board.
Line Fuse Blows VSD assembly is defective.
Replace VSD components diagnosed to
be the cause.
Chiller Fault: Low Leaving Chilled
Liquid Temperature
Leaving chilled liquid temperature drops
faster than the unit can unload.
Check for restricted flow.
Check for rapid flow changes.
Water loop is too small.
Flow is below minimum for chiller.
Chilled water sensor is defective.
Check sensor against temperature gauge
in water line.
Check sensor for intermittent operation.
Check wiring for shorts or opens.
System Fault:
Control Voltage
System fuse is blown.
Check respective system
Fuse 20FU or 21FU.
System Fault:
Abnormally High Discharge
Temperature
Discharge temperature sensor is defective. Check sensor.
Condenser tubes are dirty or scaled.
Check and clean tubes. Check water
conditioning.
Condenser water flow low.
Check site pumps, valves, and strainers.
Increase quantity of water through the
condenser to the proper value.
Condenser water too warm.
Check tower fan motor/blade, valve, and
water circulation.
Compressor issue.
Measure superheat with gauges and
thermocouple. Determine cause.
Air in condenser. Purge unit and clean the charge.
System Fault:
High Motor Temperature
High motor temperature input from one of
the sensors.
Refrigerant charge low. Check
evaporator approach.
Excess charge in system. High discharge
pressure. Check superheat.
High superheat. Feed valves NOT
controlling. Isolate cause.
Motor sensor reading incorrectly.
Program panel to ignore a single sensor.
System Fault:
Abnormally Low Suction Pressure
Low charge. Check evaporator approach.
Transducer reads incorrectly. Check transducer against a gauge.
Suction temperature sensor
reads incorrectly.
Check sensor against a thermocouple.
Insufficient refrigerant charge.
Check for leaks and charge refrigerant
into system.
Low flow. Check flow.
Feed or flow valve defective. Repair or replace valve or control.
Evaporator tubes dirty or restricted. Clean evaporator tubes.
Insufficient load for system capacity.
Check setting of low water temperature
cutout.