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TABLE 5
Emerson Motor Only
PW
LED
RX
LED
TX
LED
Motor
Blower
Action
Off
Blink
Blink
Not
Rotating
Normal
Blink
Blink
Blink
Rotating
Normal. PW blink is 100cfm/blink
Blink
Off
Blink
Not
Rotating
Verify 16X4W and motor control hp match. Verify
power to motor control.
Turn off power for 1 minute then restart. If motor still
does not rotate replace the controller.
Off
Off
Off
Not
Rotating
Verify power to the 16X4W. Turn off power then restart.
If LED's are still out, replace controller.
Motor rpm is continually adjusted internally to maintain
constant cfm. The controller monitors the static work load on
the motor and motor amp‐draw to determine the amount of
rpm adjustment. Blower rpm may be adjusted any amount in
order to maintain a constant cfm as shown in Blower Ratings
Tables. The cfm remains relatively stable over a broad range
of static pressure. Since the blower constantly adjusts rpm to
maintain a specified cfm, motor rpm is not rated. Hence, the
terms “cool speed” , “heat speed ” or “speed tap” in this manu
al, on the unit wiring diagram and on blower B3, refer to blower
cfm regardless of motor rpm.
The unit control indicates the desired cfm. The blower will
maintain the desired cfm as long as external static pressure
does not exceed 0.8”. If the system exceeds this amount, the
blower
may
enter a “cut back”, mode wherein it then slows
down to protect itself from electrical damage. During this “cut
back” mode the unit control will still indicate the
same
desired
cfm regardless of actual motor rpm.
When Harmony is used, speed taps are overridden and a
PWM signal generated by the Harmony controller continuous
ly varies motor speed based upon zone demands.
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)
Figures 8 and 9 show the two quick‐connect jacks (J48 and
J49) which connect the motor to the ML296UHV. Jack J48
is the power plug and jack J49 connects the unit controls to
the motor.
Jack J48 is the power plug. Line voltage must be applied to
J48 pins 4 and 5 in order for the motor to operate. When
using 120VAC pins 1 and 2 must be jumpered.
Jack J49 connects the unit controls to the motor. The motor
assigns priority to J49 pin 2 so that if a call for cooling and a
call for heating are concurrent, heating call overrides and
the blower operates on high speed heating tap.
