Blower Operation And Adjustments - Lennox LGH092H Installation Instructions Manual

Blower Operation and Adjustments

Belt Drive With Supply Air Inverter or Direct Drive
Units - The blower rotation will always be correct on units
equipped with an inverter or a direct drive blower.
Checking blower rotation is not a valid method of
determining voltage phasing for incoming power.
IMPORTANT
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se­
quentially to ensure correct compressor and blower*
rotation and operation. Compressor and blower are
wired in phase at the factory. Power wires are color-
coded as follows: line 1-red, line 2-yellow, line 3-blue.
1-Observe suction and discharge pressures and blow­
er* rotation on unit start-up.
2-Suction pressure must drop, discharge pressure must
rise and blower* rotation must match rotation marking.
If pressure differential is not observed or blower* rota­
tion is not correct:
3-Disconnect all remote electrical power supplies.
4-Reverse any two field-installed wires connected to
the line side of S48 disconnect or TB13 terminal strip.
Do not reverse wires at blower contactor.
5-Make sure the connections are tight.
Discharge and suction pressures should operate at
their normal start‐up ranges.
*Supply air inverter driven motors should rotate in the
correct direction; verify scroll compressor rotation
separately. Contact technical support if the blower is
rotating incorrectly.
Units Equipped With Belt Drive Blowers Controlled
by an Inverter OR Direct Drive Blowers Equipped
With Optional Voltage or Phase Detection - 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
Note - On units with staged blowers, use the Unit
Controller to start the blower. Refer to the appropriate
start-up section.
Initiate blower only (G) demand at thermostat according
to instructions provided with thermostat. Unit will cycle on
thermostat demand. The following steps apply to
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.
B-Blower Access
The blower assembly is secured to a sliding frame which
allows the blower motor assembly to be pulled out of the
unit. See figure 18, 19 or 20.
1- Loosen the reusable wire tie which secures the
blower wiring to the blower motor mounting plate.
2- Remove and retain screws on either side of sliding
frame. Pull frame toward outside of unit.
3- Slide frame back into original position when finished
servicing. Reattach the blower wiring in the previous
location on the blower motor base using the wire tie.
4- Replace retained screws on either side of the sliding
frame.
1- Loosen the reusable wire tie which secures the
controls and high voltage blower wiring to the blower
housing.
2- Remove and retain screws in front and on either side
of blower housing. Pull frame toward outside of unit.
3- Slide frame back into original position when finished
servicing. Reattach the blower wiring in the previous
location on the blower motor base using the wire tie.
4- Replace retained screws in front and on either side of
the blower housing.
Page 14
a typical electro-mechanical
Belt Drive Blowers
Direct Drive Blowers