Vi-Maintenance - Lennox LGT Series Unit Information

10-Combustion Air Inducer
The combustion air inducer is factory set and is not field
adjustable. However, operation should be monitored to
ensure proper operation. The combustion air inducer is
used to draw fresh air into the combustion chamber while
simultaneously expelling exhaust gases. The inducer op-
erates throughout the heating cycle.
On a heating demand, the ignition control is energized by
the A55 Unit Controller. The ignition control then allows
30 to 40 seconds for the combustion air inducer to vent
exhaust gases from the burners. When the combustion
air inducer is purging the exhaust gases, the combustion
air prove switch is closing proving that the combustion air
inducer is operating before allowing the ignition control to
energize.
When the combustion air prove switch is closed and the
delay is over, the ignition control activates the first stage
operator of the gas valve (low fire), the spark and the
flame sensing electrode. Sparking stops immediately after
flame is sensed.
B-Cooling System Service Checks
LGT units are factory charged and require no further ad-
justment; however, charge should be checked periodical-
ly. See section III- CHARGING.

VI-MAINTENANCE

WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at disconnect
switch(es). Unit may have multiple power
supplies.
A-Filters
LGT units use four 20 x 25 x 2" pleated throw-away type
filters. Filters may be accessed through the economizer /
filter access door. Filters should be checked monthly (or
more frequently in severe use) and cleaned or replaced
regularly. Take note of the "AIR FLOW DIRECTION" mark-
ing on the filter frame when re-installing.
NOTE-Filters must be U.L.C. certified or equivalent for
use in Canada.
B-Lubrication
All motors and blower wheels used in LGT units are prelu-
bricated; no further lubrication is required.
C-Supply Air Blower Wheel
Annually inspect supply air blower wheel for accumulated
dirt or dust. Turn off power before attempting to remove
access panel or to clean blower wheel.
D-Evaporator Coil
Inspect and clean coil at beginning of each season. Clean
using mild detergent or commercial coil cleanser. Check
condensate drain pan and line, if necessary. Flush coil
and condensate drain with water taking care not to get in-
sulation, filters and return air ducts wet. Check connecting
lines and coil for evidence of oil and refrigerant leaks.
E-Condenser Coil
Formed Coils -
Clean condenser coil annually with water and inspect
monthly during the cooling season. Clean the all-alumi-
num coil by spraying the coil steadily and uniformly from
top to bottom. Do not exceed 900 psi or a 45 angle; nozzle
must be at least 12 inches from the coil face. Take care
not to fracture the braze between the fins and refrigerant
tubes. Reduce pressure and work cautiously to prevent
damage.
Slab Coils -
Clean condenser coil annually with detergent or commer-
cial coil cleaner and inspect monthly during the cooling
season. Check connecting lines and coil for evidence of
oil and refrigerant leaks.
NOTE-If owner complains of insufficient cooling, the unit
should be gauged and refrigerant charge checked. Refer
to Gauge Manifold Attachment and Charging sections in
this manual.
F-Electrical
1 - Check all wiring for loose connections.
2 - Check for correct voltage at unit (unit operating).
3 - Check amp-draw on both condenser fan motor and
blower motor.
Fan Motor Rating Plate ____ Actual ________
Indoor Blower Motor Rating Plate____ Actual____
4 - Check crankcase heater temperatures to ensure
they are operating.
5 - Check compressor sump thermistors to ensure they
are making contact with compressor shell (ultra
high efficiency units only).
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