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10-Combustion Air Inducer
The combustion air inducer is factory set and is not field ad
justable. However, operation should be monitored to en
sure proper operation. The combustion air inducer is used
to draw fresh air into the combustion chamber while simul
taneously expelling exhaust gases. The inducer operates
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 ex
haust gases from the burners. When the combustion air in
ducer is purging the exhaust gases, the combustion air
prove switch is closing proving that the combustion air in
ducer is operating before allowing the ignition control to en
ergize. 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 adjust
ment; however, charge should be checked periodically.
See section III- CHARGING.
VI-MAINTENANCE
A-Filters
LGT units use four 20 x 25 x 2” pleated throw-away type fil
ters. Filters may be accessed through the economizer / fil
ter 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 ac
cess panel or to clean blower wheel.
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.
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 insula
tion, 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-aluminum 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 cautious
ly to prevent damage.
Slab Coils -
Clean condenser coil annually with detergent or commer
cial coil cleaner and inspect monthly during the cooling sea
son. 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 sec
tions 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 ef
ficiency units only).
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