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11 - Inspect the furnace return air duct connection to
ensure the duct is sealed to the furnace. Check for
air leaks on supply and return ducts and seal where
necessary.
12 - Check the condition of the furnace cabinet insulation
and repair if necessary.
13 - Perform a complete combustion analysis during the
furnace inspection to ensure proper combustion
and operation. Consult Service Literature for proper
combustion values.
14 -
Verify operation of CO detectors and replace
batteries as required.
Perform a general system test. Turn on the furnace to
check operating functions such as the start-up and shut-
off operation.
1 - Check the operation of the ignition system, inspect
and clean flame sensor. Check microamps before
and after. Check controls and safety devices (gas
valve, flame sensor, temperature limits). Consult
Service Manual for proper operating range. Thermal
Limits should be checked by restricting airflow and
not disconnecting the indoor blower. For additional
details, please see Service and Application Note
H049.
2 -
Verify that system total static pressure and airflow
settings are within specific operating parameters.
3 - Clock gas meter to ensure that the unit is operating
at the specified firing rate for each stage of
operation. Check the supply pressure and the
manifold pressure on both low fire and high fire. If
manifold pressure adjustment is necessary, consult
the Service Literature for unit specific information
on adjusting gas pressure. Not all gas valves are
adjustable. Verify correct temperature rise.
Repair Parts List
The following repair parts are available through Lennox
dealers. When ordering parts, include the complete fur-
nace model number listed on the CSA International name-
plate -- Example: ML196UH045XE36B. All service must
be done by a licensed professional installer (or equiva-
lent), a service agency, or the gas supplier.
Cabinet Parts
Upper access panel
Blower access panel
Top Cap
Control Panel Part
s
Transformer
Integrated control
Door interlock switch
Blower Parts
Blower wheel
Motor
Motor mounting frame
Motor capacitor
Blower housing cutoff plate
Heating Parts
Flame Sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switch
Ignitor
Primary limit control
Flame rollout switches
