Motor Start-Up; Power Choke; Blower B3 Harness Connectors - Lennox G71MPP SERIES Unit Information

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 elec-
tronic 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 200rpm within 13 seconds, the motor
shuts down. Then the motor will immediately attempt a re-
start. The shutdown feature provides protection in case of a
frozen bearing or blocked blower wheel. The motor may at-
tempt to start eight times. If the motor does not start after the
eighth try, the controller locks out. Reset controller by momen-
tarily 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 attempt-
ing to service motor.
DANGER
Disconnect power from unit and
wait at least five minutes to allow
capacitors to discharge before at-
tempting to service motor. Failure
to wait may cause personal injury
or death.
Power Choke (L13)
A choke coil is used on G71MPP 5 ton 1 hp units. The
choke is located on the blower housing and is used to supress
transient current spikes.

BLOWER B3 HARNESS CONNECTORS

SHAFT
MOTOR with IINTEGRATED
CONTROLLER
J48 5 Pin
J49 4 Pin
J48 5 Pin Line Voltage Connector
Page 29
P48 5 Pin
J49 4 Pin Control Connector
FIGURE 9
P49 4 Pin