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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 supply, manifold and signal pressures at
35, 70 and 100% capacity as outlined in the unit
Service Literature. 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.
NOTE - After any heavy snow, ice or frozen fog event the
furnace vent pipes may become restricted. Always check
the vent system and remove any snow or ice that may be
obstructing the plastic intake or exhaust pipes.
Winterizing and Condensate Trap Care.
1 - Turn off power to the unit.
2 - Have a shallow pan ready to empty condensate
water.
3 - Remove the drain plug from the condensate trap
and empty water. Inspect the trap then reinstall the
drain plug and refill trap with water.
Repair Parts
The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model
number listed on the nameplate -- Example: SLP99DF070V36B. All service must be performed by a licensed profes-
sional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Outer access panel
Blower access panel
Top cap
Control Panel Parts
Transformer
Integrated control
Door interlock switch
Circuit breaker
Blower Parts
Blower wheel
Motor
Motor mounting frame
Blower housing cut-off plate
Cleaning the Burner Assembly
1 - Turn off electrical and gas power supplies to furnace.
Remove upper and lower furnace access panels.
2 - Disconnect the 2-pin plug from the gas valve.
3 - Remove the burner box cover.
4 - Disconnect the gas supply line from the gas valve.
Remove gas valve/manifold assembly.
5 - Mark and disconnect sensor wire from the sensor.
Disconnect2-pin plug from the ignitor at the burner
box.
6 - Remove four screws which secure burner box
assembly to vest panel. Remove burner box from
the unit.
7 - Use the soft brush attachment on a vacuum cleaner
to gently clean the face of the burners. Visually
inspect the inside of the burners and crossovers for
any blockage caused by foreign matter. Remove
any blockage.
8 - Reconnect the sensor wire and reconnect the 2-pin
plug to the ignitor wiring harness.
9 - Reinstall the burner box assembly using the existing
four screws. Make sure that the burners line up in
the center of the burner ports.
10 - Reinstall the gas valve manifold assembly.
Reconnect the gas supply line to the gas valve.
Reinstall the burner box cover.
11 - Reconnect 2-pin plug to gas valve.
12 - Replace the blower compartment access panel.
13 - Refer to instruction on verifying gas and electrical
connections when re-establishing supplies.
14 - Follow lighting instructions to light and operate
furnace for 5 minutes to ensure that heat exchanger
is clean and dry and that furnace is operating
properly.
15 - Replace heating compartment access panel.
Heating Parts
Flame sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orifices
Pressure switches
Ignitor
Primary limit control
Flame rollout switches
Page 57
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