Lennox LGM Series Manual page 25

C-Blower Compartment
Units are equipped with variable speed, direct drive blow­
ers. The installer is able to enter the design-specified sup­
ply air CFM into the Unit Controller for optimal efficiency.
The Unit Controller calibrates the supply air volume which
eliminates the need to manually take duct static measure­
ments. Refer to C-Adjusting Unit CFM - Ultra High Efficien­
cy Direct Drive Blowers.
IMPORTANT
Compressor two is the only component that must be
checked to ensure proper phasing. Follow "COOLING
START-UP" section of installation instructions to ensure
proper compressor and blower operation.
The Unit Controller checks the incoming power during
start-up. If the voltage or phase is incorrect, the Unit Con­
troller will display an alarm and the unit will not start.
A-Blower Operation
Refer to the Unit Controller Setup Guide to energize blower.
Use the mobile service app menu; see SERVICE > TEST.
In thermostat control mode, the Unit Controller will stage
the blower between low and high speed. In zone sensor
control mode, the Unit Controller will vary (VAV) the blower
between low and high speed.
WARNING
1-Make sure that unit is installed in accordance with the
installation instructions and applicable codes.
2-Inspect all electrical wiring, both field‐ and factory‐
installed, for loose connections. Tighten as required.
3-Check to ensure that refrigerant lines do not rub against
the cabinet or against other refrigerant lines.
4-Check voltage at disconnect switch. Voltage must be
within range listed on nameplate. If not, consult power
company and have voltage condition corrected before
starting unit.
5-Make sure filters are new and in place before start‐up.
Initiate blower only (G) demand at thermostat according to
instructions provided with thermostat. Unit will cycle on
thermostat demand. The following steps apply to applica­
tions using a typical electro-mechanical thermostat.
1- Blower operation is manually set at the thermostat sub­
base fan switch. With fan switch in ON position, blow­
ers will operate continuously.
2- With fan switch in AUTO position, the blowers will cycle
with demand. Blowers and entire unit will be off when
system switch is in OFF position.
NOTE - Blower operation mode can also be initiated by the
mobile service app.
B-Blower Access
The blower assembly is secured to a sliding frame which al­
lows the blower assembly to be pulled out of the unit. See
figure 14.
1- Loosen the reusable wire tie which secures the con­
trols and high voltage blower wiring to the blower hous­
ing. Disconnect the pressure sensor low voltage wire
harness.
2- Remove and retain screws on either side (and on the
front for direct drive) of sliding frame. Use the metal
handle to pull frame toward outside of unit.
3- Slide frame back into original position when finished
servicing. Reattach the blower wiring in the previous lo­
cation using the wire tie. Reconnect pressure sensor
low voltage wire harness.
4- Replace retained screws.
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