Troubleshooting - Unit - LG AR-DR12-05A Installation And Operation Manual

TROUBLESHOOTING - UNIT

Symptom
Blown fuse or open circuit breaker.
Defective motor or capacitor.
Blower fails to
operate
Motor overloaded.
Electrical.
Control power (24 VAC) wiring run is
too long. (Resistance should not exceed
0.75 ohms).
Motor starters
"chatter" or do not
Incoming supply power is less than
pull in
anticipated. Voltage supplied to starter
coil must be within +10% / -15% of
nominal voltage stated on the coil.
Static pressures are higher than design.
Motor voltage incorrect.
Motor over amps
Motor horsepower too low.
Shorted windings in motor.
Unit damper not fully open.
System static pressure too high.
Blower speed too low.
Fan wheels are operating backwards.
Low airflow (cfm)
Dirty filter.
Leaks in ductwork.
Elbows or other obstructions may be
obstructing fan outlet.
Blower fan speed too high.
High airflow (cfm) Filter(s) not in place.
Insufficient static pressure (Ps). (airflow
resistance)
Fan wheel rubbing on inlet.
Bearings.
Excessive noise or
Loose wheel on shaft.
vibration
Motor base or blower loose.
Noise being transmitted by duct.
54
Possible Cause
Replace fuse or reset circuit breaker and check amps.
Replace.
Reset VFD and check amps.
Check for On/Off switches. Check for correct supply voltage. Check Control
wiring.
Shorten wiring run to mechanical room or install a relay to turn unit on/
off. Consult factory for relay information. Increase wire gauge size so that
resistance is 0.75 ohms or less.
Need to increase supply power or use a special control transformer which is
sized for the actual supply power.
Check for dirty filters. Improve ductwork.
Check motor wiring. Check motor nameplate versus supplied voltage.
See specifications and catalog for fan curves to determine if horsepower is
sufficient.
Replace motor.
Adjust damper linkage or replace damper motor.
Improve ductwork to eliminate losses using good duct practices.
Check maximum motor RPM and compare with catalog data. Verify that
external control wiring is in place if required.
For 3-phase, see Direction of Fan Wheel Rotation Direction in Start-Up,
Components section.
Replace filters or follow cleaning procedures in Routine Maintenance section of
this manual.
Repair.
Correct or improve ductwork.
Check for correct maximum fan RPM. Decrease maximum fan speed if
necessary in the VFD.
Install filters.
Induce Ps into system ductwork. Make sure grilles and access doors are
installed. Decrease fan speed if necessary.
Adjust wheel and/or inlet cone. Tighten wheel hub or bearing collars on shaft.
Replace defective bearing(s). Lubricate bearings. Tighten collars and
fasteners.
Tighten wheel hub.
Tighten mounting bolts.
Make sure ductwork is supported properly. Make sure ductwork metal
thickness is sized for proper stiffness. Check duct size at discharge to ensure
that air velocities are not too high.
Due to our policy of continuous product innovation, some specifications may change without notification.
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Corrective Action