Always have a completed Pre Start-Up Checklist, unit Start-Up Checklist, and Optional Accessories Checklist prior to requesting parts or
service information.
Symptom Possible Cause Corrective Action
Blower fails to
operate
Blown fuse or open circuit breaker.
Replace fuse or reset circuit breaker and
check amps.
Defective motor or capacitor. Replace.
Motor starter overloaded. Reset starter and check amps.
Electrical.
Check for On/Off switches. Check for correct
supply voltage.
Drive.
Check for broken or loose belts. Tighten
loose pulleys.
Motor starters
“chatter” or
do not pull in
Control power (24 VAC) wiring run is too
long (resistance should not exceed 0.75
ohms).
Shorten wiring run to mechanical room or
install a relay which will turn unit on/off.
Consult Factory for relay information.
Incoming supply power is less than anticipated.
Voltage supplied to starter coil must be within
+10% / -15% of nominal voltage stated on the
coil.
Need to increase supply power or use a
special control transformer which is sized for
the actual supply power.
Motor over amps
CFM too high. Check cfm and adjust drives if needed.
Static pressures are higher or lower than
design.
If higher, ductwork should be improved.
If lower, fan rpm should be lower.
Blower rotation is incorrect. Check rotation and reverse if necessary.
Motor voltage incorrect.
Check motor nameplate versus supplied
voltage.
Motor horsepower too low.
See specifications and catalog for fan curves
to determine if horsepower is sufficient.
Shorted windings in motor. Replace motor.
Low airflow (cfm)
Unit damper not fully open.
Adjust damper linkage or replace damper
motor.
System static pressure too high.
Improve ductwork to eliminate losses using
good duct practices.
Blower speed too low.
Check for correct drives and rpm with
catalog data.
Fan wheels are operating backwards.
For 3-phase, see Direction of Fan Wheel
Rotation under Unit Start-Up section.
Dirty filter or energy wheel.
Follow cleaning procedures in Routine
Maintenance section.
Leaks in ductwork. Repair.
Elbows or other obstructions may be
obstructing fan outlet.
Correct or improve ductwork.
Belt slippage. Adjust belt tension.
High airflow (cfm)
Blower fan speed too high.
Check for correct fan rpm. Decrease fan
speed if necessary.
Filter(s) not in place. Install filters.
Insufficient static pressure (Ps) (airflow
resistance).
Induce Ps into system ductwork. Make
sure grilles and access doors are installed.
Decrease fan speed if necessary.
Troubleshooting – Unit
Energy Recovery Ventilator30
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