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11-Combustion Air Blower
The combustion air blower is factory set and is not field adjust-
able. However, operation should be monitored to ensure prop-
er operation. The combustion air blower is used to draw fresh
air into the combustion chamber while simultaneously ex-
pelling exhaust gases. The blower operates throughout
the heating cycle.
On a heating demand, the ignition control is energized by the
main control module A55. The ignition control then allows a
pre-purge of 30 to 40 seconds for the combustion air blower to
vent exhaust gases from the burners. When the com-
bustion air blower is purging the exhaust gases, the
combustion air prove switch is closing proving that the com-
bustion air blower is operating before allowing the ignition con-
trol to energize. When the combustion air prove switch is
closed and the delay is over, the ignition control activates the
gas valve, the spark and flame sense electrode. The spark will
end when flame is sensed. Units with the White Rodgers gas
valve will activate on first stage (low fire) with the spark and
the flame sensing electrode. Sparking stops immedi-
ately after flame is sensed.
B-Cooling System Service Checks
LGA / LCA units are factory charged and require no further ad-
justment; however, charge should be checked periodically us-
ing the subcooling method. The subcooling method compares
actual liquid temperature with the condensing temperature of
the refrigerant.
1-Gauge Manifold Attachment
Service gauge ports are identified in figure 7. Attach high
pressure line to discharge line schrader port and the low pres-
sure line to the suction line schrader port.
NOTE-When unit is properly charged discharge and suc-
tion line pressures should approximate those in tables 10
through 14.
VI-MAINTENANCE
CAUTION
Electrical shock hazard. Turn off power to unit
before performing any maintenance, cleaning or
service operation on the unit.
A-Filters
LGA / LCA units are equipped with two 16" x 25" x 2"
(406mm x 635mm x 51mm) pleated throw-away type fil-
ters. Filters may be accessed through the economizer /
filter access door at the end of the unit. Filters should be
checked monthly (or more frequently in severe use) and
replaced regularly. Take note of the "AIR FLOW DI-
RECTION" marking on the filter frame when re-instal-
ling.
NOTE-Filters must be U.L.C. certified or equivalent for
use in Canada.
B-Lubrication
All motors and blower wheels used in LGA / LCA units
are prelubricated; 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.
Be careful when servicing unit to avoid accidental
contact with sharp metallic edges which may
cause personal injury.
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
Clean condenser coil annually with detergent or com-
mercial coil cleaner and inspect monthly during the cool-
ing 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____
Page 40
CAUTION
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