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Motor Start-Up
When B3 begins start-up, the motor gently vibrates back
and forth for a moment. This is normal. During this time the
electronic controller is determining the exact position of the
rotor. Once the motor begins turning, the controller slowly
eases the motor up to speed (this is called "soft-start"). The
motor may take as long as 10-15 seconds to reach full speed.
If the motor does not reach 200 rpm within 13 seconds, the
motor shuts down. Then the motor will immediately attempt
a restart. The shutdown feature provides protection in case
of a frozen bearing or blocked blower wheel. The motor may
attempt to start eight times. If the motor does not start after
the eighth try, the controller locks out. Reset controller by
momentarily turning off power to unit.
The DC filter capacitors inside the controller are connected
electrically to the motor supply wires. The capacitors take
approximately 5 minutes to discharge when the disconnect
is opened. For this reason it is necessary to wait at least 5
minutes after turning off power to the unit before attempting
to service motor.
DANGER
Disconnect power from unit and wait at
least five minutes to allow capacitors to
discharge before attempting to service
motor. Failure to wait may cause personal
injury or death.
Power Choke (L13)
A choke coil is used on units equipped with 1 hp motors.
The choke is located on the blower housing and is used to
suppress transient current spikes.
31-5000723 Rev. 0
Remove Blower from Unit
1. Remove unit access panels, control box, bolts and
wiring jackplugs.
2. Slide blower out front of unit.
Troubleshooting Motor Operation
To verify motor operation see steps below and Figure 9 and
Figure 10.
1. Remove J48 (5 pin power plug) from P48 on the motor.
2. With the power on at the furnace and door switch
depressed, use a test meter to verify 120V between pins
4 and 5 on J48.
3. Reconnect J48 to P48 on the motor.
4. Remove J49 (4 pin low voltage connector) from P49 on
the motor.
5. Using test jumpers, apply 24V to pins 3 and 4 on P49
on the motor.
NOTE: Do not apply 24V to pins 2 and 4 on P49. Doing
so will cause permanent damage to the motor.
6. Motor should run at 75%.
7. Test is complete. Remove jumpers and reconnect plugs.
Another option is to use the TECMate PRO motor tester
with the 16 to 4 pin adaptor. The use of the TECMate PRO
isolates the motor from the integrated control. Follow the
instructions provided with the kit. If the motor runs, do not
replace.
Page 25
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