WaterFurnace Series NXW - Manual (Page 32)

32
ENVISION 2 NKW 50Hz REVERSIBLE CHILLER INSTALLATION MANUAL
Should a major problem develop, refer to the following information for possible causes and corrective steps.
If compressor won’t run:
1. The fuse may be open or the circuit breaker is tripped. Check electrical circuits and motor windings for shorts or
grounds. Investigate for possible overloading. Replace fuse or reset circuit breakers after fault is corrected.
2. Supply voltage may be too low. Check it with a volt meter.
3. Control system may be faulty. Check control for correct wiring of aquastat and check the 24 volt transformer for
proper voltage.
4. Wires may be loose or broken. Replace or tighten.
5. The low pressure switch may have tripped due to one or more of the following:
a) Heating
1) Plugged heat exchanger on source side
2) Water flow source side -(Low)
3) Water too cold source side
4) Low refrigerant
b) Cooling
1) Plugged heat exchanger on load side
2) Water flow load side - (Low)
3) Water too cold load side
4) Low refrigerant
6. The high pressure switch may have tripped due to one or more of the following:
a) Heating
1) Plugged heat exchanger on load side
2) Low water flow load side
3) Water too warm load side
b) Cooling
1) Plugged heat exchanger on source side
2) Low water flow on source side
3) Water too warm source side
7. The compressor overload protection may be open. Disconnect power. Remove S1 & S2 wires from the compressor
protection module. Measure the resistance between the S1 & S2 wires. If the resistance measures > 2750 ohms, then
the internal compressor resistance has tripped the compressor protection module. The compressor protection module
will reset after a 30 minute delay and the resistance measures < 2250 ohms. Cycling the power off for a minimum of 3
seconds will manually reset the compressor module. The internal compressor resistance must measure < 2250 ohms for
the compressor module to reset.
8. The internal winding of the compressor motor may be grounded to the compressor shell. If so, replace the compressor.
9. The compressor winding may be open or shorted. Disconnect power. Check continuity with ohm meter. If the winding is
open, replace the compressor.
If sufficient cooling or heating is not obtained:
1. Check control for improper location or setting.
2. Check for restriction in water flow.
3. Check refrigerant subcooling and superheat for proper refrigerant charge and expansion valve operation.
4. The reversing valve may be defective and creating a bypass of refrigerant. If the unit will not heat, check the reversing
valve coil.
If the unit operation is noisy:
1. Check compressor for loosened mounting bolts. Make sure compressor is floating free on its isolator mounts. Check for
tubing contact with the compressor or other surfaces. Readjust it by bending slightly.
2. Check screws on all panels.
3. Check for chattering or humming in the contactor or relays due to low voltage or a defective holding coil. Replace the
component.
4. Check for proper installation of vibration absorbing material under the unit.
5. Check for abnormally high discharge pressures.
6. Compressor rotation incorrect
Troubleshooting