Lennox G50UHi Unit Information page 13

Blower Control Module (Figure 10)
G50UHi units are equipped with a blower control module
which offers a variety of indoor blower speeds for selection.
The module is wired between the SureLight ignition control
board and the indoor blower motor. The module alters the
frequency and voltage of the power supply to the blower to
control blower speed. The module provides consistent
CFM over a wider range of operating static pressures.
The module also features a dehumidification option. This
option requires the use of a thermostat which includes a hu-
midity sensor, as well as a relay, which must both be or-
dered separately. When this optional feature is used, the
blower control module shifts the indoor blower motor to a
lower speed (determined by the selector jumper) when the
indoor thermostat indicates a dehumidification require-
ment.
The module includes a ramping profile selector, which of-
fers passive humidity control during cooling operation. This
feature does not require the use of a specific thermostat or
an additional relay. There are three available ramping pro-
files. When one of the ramping profiles is used, the indoor
blower is initially engaged at a lower speed to provide addi-
tional humidity control. After the selected time period
(7−1/2, 10, or 15 minutes), the blower motor shifts to the
regularly selected cooling speed.
The module/bracket assembly is located on the blower
scroll just below the SureLight control board. Blower
speeds are adjusted by altering the position of blower
speed selector jumpers.
Blower Control Module Settings
DANGER
Disconnect power from unit and
wait at least 30 seconds to allow
capacitors to discharge before re-
moving blower control module
cover. Failure to wait may cause
personal injury or death.
6−PIN CONNECTOR
TO SURELIGHT
CONTROL
G50UHi BLOWER CONTROL MODULE
SELECTOR PINS
WITH JUMPERS
(Options detailed at right)
FIGURE
Page 13
Remove the cover panel from the module to access the se-
lector jumpers. There are five selector pins in each column.
These pins, when jumpered, correspond with four selec-
tion options for each function. The speed (or ramp) selec-
tion is listed in the space between the two pins. There are
eight blower speeds and four ramping options available for
selection on the control module. Refer to table 9 and figure
10. The blower speed settings and the corresponding
CFMs are given in the BLOWER DATA section.
The ramping options provide a means of controlling humid-
ity during cooling operation without the use of a humidity
sensor or additional relay.
Ramping Option A (Factory Selection)
D Motor runs at 82% for approximately 7−1/2 minutes.
D If demand has not been satisfied after 7−1/2 minutes,
motor runs at 100% until demand is satisfied.
D Once demand is met, motor ramps down to off.
7−1/2 MIN
OFF 82%CFM
Ramping Option B
D Motor runs at 75% for approximately 10 minutes.
D If demand has not been satisfied after 10 minutes, mo-
tor runs at 100% until demand is satisfied.
D Once demand is met, motor ramps down to off.
10 MIN
OFF 75%CFM
Ramping Option C
D Motor runs at 75% for approximately 15 minutes.
D If demand has not been satisfied after 15 minutes, the
motor runs at 100% until demand is satisfied.
D Once demand is met, motor ramps down to off.
15 MIN
OFF 75%CFM
COOL
1
1
3
3−PIN MOTOR
4
CONNECTOR
COOL
1
1
3
4
100% CFM
COOLING DEMAND
100% CFM
COOLING DEMAND
100% CFM
COOLING DEMAND
3−Ton Blower
HEAT FAN DEHUM. RAMP
3
2
1
5
2 4
3
6
5
7
6
4
4−Ton and 5−Ton Blowers
HEAT FAN DEHUM. RAMP
3
2
2
3
5
4
4
6
5
7
5 6
OFF
OFF
OFF
OFF
A
B
C
OFF
A
B
C