Vi-Maintenance - Lennox LDT Series Information

TABLE 13
Nominal Signal
Manufacturer
Microamps
UTEC 0.5 - 1.0
NOTE-If the meter scale reads 0, the leads are
reversed. Disconnect power and reconnect leads for
proper polarity.
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
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
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
LDT units are factory charged and require no further
adjustment; however, charge
periodically using the liquid temperature plots in 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 discon­
nect switch(es). Unit may have multiple
power supplies.
Drop Out
.09
should be checked
Page 36
A-Filters
LDT units use six 24 X 24 X 2" fiberglass 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"
marking on the filter frame when re-installing.
B-Lubrication
All motors and blower wheels used in LDT units are
lubricated; 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
insulation, 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
commercial coil cleaner and inspect monthly during the
cooling season. Check connecting lines and coil for
evidence of oil and refrigerant leaks.
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____