Quantech QWC4, Installation Operation & Maintenance, Page: 149 / 156

QUANTECH
149
SECTION 8 - TROUBLESHOOTING
FORM QWC4-NM1 (221)
ISSUE DATE: 02/28/2021
8
PROBLEM POSSIBLE CAUSE ACTION
System Fault:
Motor Current Limiting
High motor current has activated current
limiting.
Ambient temperature is high.
Normal response from controller
Remote or panel limiting is in
effect. Normal response.
Excess charge in system.
Adjust charge.
VSD Fault:
High Baseplate Temperature
Coolant level low. Add coolant.
Coolant pump is defective. Replace coolant pump.
VSD board is defective. Replace VSD logic board.
Sensor is defective. Replace defective sensor.
VSD Fault:
Low DC Bus Voltage
Line voltage sag.
Evaluate indicators of power feed at time
of event.
SCR or trigger board is defective. Check VSD.
System Fault:
High Evaporator Pressure
System overload.
Make sure the compressors are loaded
(without overloading the motor) until the
load decreases.
System Fault:
1. Compressor Starts
2. Normal Oil Pressure Develops
3. Pressure Fluctuates
4. Compressor Stops on Oil
Pressure Fluctuation
Unusual starting conditions exist, i.e., oil
foaming in reservoir and piping, due to
lowered system pressure.
Drain the oil from the oil separator and
charge new oil into the oil separator.
Burned out compressor heater. Replace compressor heater.
System Fault:
Oil Pressure Gradually Decreases
Oil filter is dirty. Change oil filter.
Extreme bearing wear.
Call Quantech Field Service Office to
evaluate compressor.
System Fault:
Oil Return System Ceases to
Return an Oil Refrigerant Sample
Filter in oil return system dirty. Replace old oil filter with a new filter.
Oil return eductor jet or orifice is clogged.
Remove eductor, inspect for dirt.
Remove dirt, using solvent and replace.
System Fault:
System Fails to Deliver Oil Pressure
Faulty oil pressure transducer. Faulty
wiring/connectors.
Replace oil pressure transducer.
Excessive Noise and Vibration
Bearing damage or excessive wear.
Call Quantech Field Service Office to
evaluate compressor.
Refrigerant flood back. Correct system problem.
Chiller vibration isolators installed
improperly
Install isolators properly according to
instructions in this manual.
Room acoustics are poor. Evaluate sound attenuation.
Piping supports not supporting load. Adjust piping supports.
Gradual Oil Loss with an Oil Level
in the Separator Sight Glass
Oil level is too high. Lower oil level.
Refrigerant carryover or liquid injection
overfeeding.
Adjust refrigerant level setpoint. Check
control valves.
NOTE: Always turn OFF power to the chiller and make sure the DC Bus voltage has bled off when opening the VSD cabinet.
TABLE 46 - TROUBLESHOOTING GUIDE (CONT'D)