8
HMD IO&M
B51242-002
No
No
No
No
No
Is the proper power
supply at the main
disconnect?
1. Compare the supplied voltage, hertz, and phase with the motor’s
nameplate information.
2. Make sure disconnect switch is on.
Replace 480-120v transformer #A
1. Make sure supply switch is on.
1. Correct supply fan overload if tripped. Check for proper voltage, amps
and RPMs.
2. Check optional exhaust fan interlocks
Is there 120 VAC
between terminals X2 &
X1 on transformer #A?
Is there 120 VAC between
terminal block #2 &
circuit breaker terminal 2?
Is there 120 VAC
between terminal blocks
1 & 5?
Is there 120 VAC
between across A1 &
A2 on supply contactor?
1. Replace fan belt, if broken.
2. Repair or replace motor or capacitor if needed.
3. Repair motor fuse if needed.
4. Repair or replace one or more of the motor
wiring legs, if needed.
At this time the supply contactor
should pull in, passing power to the
supply motor & blower should start.
Yes
Yes
Yes
Yes
Yes
1. Install the optional damper limit switch, if not installed. If holding, wait
for actuator to fully open or adjust the limit switch.
2. Repair or replace fan relay if not energizing. Check for loose
connection.
Troubleshooting
Blower does not operate
Refer to the control panel parts list when troubleshooting.
