Initial Power Up; Motor Start-Up; External Operation (Speed Tap Priority); Power Choke - Lennox G61MPV Service Manual

Initial Power Up

When line voltage is applied to B3, there will be a large inrush
of power lasting less than 1/4 second. This inrush charges a
bank of DC filter capacitors inside the controller. If the discon-
nect switch is bounced when the disconnect is closed, the dis-
connect contacts may become welded. Try not to bounce the
disconnect switch when applying power to the unit.

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 speed tap 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 change speed taps.
DANGER
Disconnect power from unit and
wait at least five minutes to allow
capacitors to discharge before at-
tempting to adjust motor speed tap
settings. Failure to wait may cause
personal injury or death.

External Operation (Speed Tap Priority)

Figure 10 shows the two quick-connect jacks (J48 and J49)
which connect the motor to the G61MPV. Jack J48 is the
power plug and jack J49 connects the unit controls to the
motor.
Line voltage must be applied to J48 pin 5 in order for the
motor to operate. When using 120VAC pins 1 and 2 must
be jumpered. When control voltage is applied to J49 pin 3
and 15, the motor is energized on the continuous fan mode.
When voltage is applied to J49 pin 2 in addition to pin 3 and
15 (first stage heating), the blower is energized on the low
speed heating tap. When voltage is applied to J49 pin 13 in
addition to pin 3 and 15 (second stage heating), the blower
is energized on the high speed heating tap. The motor as-
signs priority to J49 pin 2 so that if a call for cooling and a call
for heating are concurrent, heating call overrides and the blow-
er operates on high speed heating tap.
BLOWER B3 HARNESS CONNECTORS
POWER
CONNECTOR J48
1
J48
PIN 1 - Jumper PIN 1 to PIN2 for 120VAC line input only.
PIN 2 - Jumper PIN 1 to PIN2 for 120VAC line input only.
PIN 3 - Ground
PIN 4 - AC Line
PIN 5 - AC Line
Power Choke (L13)
A choke coil is used on G61MPV 5 ton 1 hp units. The
choke is located on the blower housing and is used to supress
transient current spikes.
If the G61MPV or its electronically controlled blower motor is
improperly or inadequately grounded, it may cause television
interference (commonly known as RFI or radio frequency in-
terference).
This interference is caused by internal switching fre-
quencies of the motor controller. TV interference may
show up as small specks or lines which randomly appear
on the TV screen accompanied by pops or clicks in the sound.
Before attempting any service, make sure the indoor unit is
causing the interference. To check, disconnect power to indoor
unit then check TV for continued signs of interference.
TV interference may be stopped by making sure the mo-
tor is solidly grounded to the cabinet (metal to metal) and
by making sure the cabinet is solidly grounded. If TV in-
terference persists, make sure the television (and all af-
fected RF appliances) are moved away from the G61MPV.
Also make sure affected appliances are connected to a sepa-
rate electrical circuit.
Page 40
CONTROL
CONNECTOR J49
J49
1
PIN 1 - C1
PIN 2 - W / W1
PIN 3 - C2
PIN 4 − Delay
PIN 5 - Cool
PIN 6 - Y1
PIN 7 - Adjust
PIN 8 - 0ut
PIN 9 - 0
PIN 10 - DS(PWM)
PIN 11 - Heat
PIN 12 - R
PIN 13 - EM / W2
PIN 14 - Y / Y2
PIN 15 - G
PIN 16 - Out +
FIGURE 10
Precautions