Blower Operation And Adjustments - Lennox LGM092U Installation Instructions Manual

Blower Operation
Units are equipped with variable speed, direct drive
blowers. The installer
design-specified supply 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 measurements. Refer to C-Adjusting Unit
CFM - Ultra High Efficiency 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 en­
sure proper compressor and blower operation.
The Unit Controller checks the incoming power during
start-up. If the voltage or phase is incorrect, the Unit
Controller 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.
is able to enter
Initiate blower only (G) demand at thermostat according
to instructions provided with thermostat. Unit will cycle on
thermostat demand. The following steps apply to
the
applications using
thermostat.
1- Blower operation is manually set at the thermostat
subbase fan switch. With fan switch in ON position,
blowers 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
allows the blower assembly to be pulled out of the unit.
See figure 21.
1- Loosen the reusable wire tie which secures the
controls and high voltage blower wiring to the blower
housing. 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
location using the wire tie. Reconnect pressure
sensor low voltage wire harness.
4- Replace retained screws.
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