Unit - Greenheck RV Installation, Operation And Maintenance Manual

Troubleshooting – Unit
Symptom Possible Cause
Blown fuse or open circuit breaker.
Defective motor or capacitor.
Blower fails
Motor overloaded.
to operate
Electrical.
Control power (24 VAC) wiring run is too
long. (Resistance should not
Motor
exceed 0.75 ohms).
starters
"chatter" or
Incoming supply power is less than
do not 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.
Low airflow
(cfm) Fan wheels are operating backwards.
Dirty filter.
Leaks in ductwork.
Elbows or other obstructions may be
obstructing fan outlet.
Blower fan speed too high.
High airflow Filter(s) not in place.
(cfm)
Insufficient static pressure (Ps).
(airflow resistance)
Fan wheel rubbing on inlet.
Bearings.
Excessive
Loose wheel on shaft.
noise or
Motor base or blower loose.
vibration
Noise being transmitted by duct.
Always have a completed Pre-Start-Up Checklist and Start-Up Checklist prior to requesting parts or service
information.
®
Corrective Action
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.
Packaged Rooftop Ventilator
21