Lennox G50UHi Unit Information page 35

Indoor blower motor does not operate at
Check blower speed jumpers on blower control module to ensure proper selection.
Is motor operating properly?
NO
D Ensure that 6−pin connector is securely plugged into blower control module.
D Ensure that 3−pin motor connector is securely connected.
D Check power supply wiring to blower control module from 120HOT and neutral
terminals on SureLight® control board.
D Ensure that leads from 6−pin connector are securely connected to the proper terminals
on the SureLight® control board.
D Make sure blower access panel is replaced properly to close door interlock switch and
energize SureLight® control board.
D Check for proper demand from thermostat.
Is motor operating properly?
NO
CHECK BLOWER CONTROL MODULE
Proper blower control module must be installed:
D 79M82 −− 3−ton models.
D 79M83 −− 4−ton models.
D 79M84 −− 5−ton models.
YES
Blower control module is not working
properly. Replace blower
module.
The blower control module and single−tap motor used in G50UHi units are
designed specifically for use with one another. If a PSC blower motor is used
to provide emergency operation, the PSC motor must be connected to the
SureLight® control board, rather than the blower control module. If the
SureLight® control board is used to control blower operation in an emergency
situation, the single−tap motor must be temporarily replaced using a PSC
motor. If these instructions are ignored, control board or blower motor failure
may result, causing a potentially hazardous condition.
PROBLEM
the correct speed.
CHECK SPEED SETTINGS
YES
Recheck all wiring connections.
CHECK WIRING
YES
Recheck all wiring connections.
control
CAUTION
Page 35