Page 7
3 -   Clock gas meter to ensure that the unit is operating 
at the specied ring 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 
specic  information  on  adjusting  gas  pressure. 
Not  all  gas  valves  are  adjustable.  Verify  correct 
temperature rise
 CAUTION
As with any mechanical equipment, contact with 
sharp sheet metal edges can result in personal 
injury. Take care while handling this equipment and 
wear gloves and protective clothing.
Perform  a  general  system  test.  Turn  on  the  furnace  to 
check operating functions such as the start-up and shut-
o operation.
1 -   Check the operation of the ignition system, inspect 
and  clean  ame  sensor.  Check  microamps  before 
and  after.  Check  controls  and  safety  devices  (gas 
valve,  ame  sensor,  temperature  limits).  Consult 
Service Manual for proper operating range. Thermal 
Limits should be checked by restricting airow and 
not disconnecting the indoor blower. For additional 
details,  please  see  Service  and  Application  Note 
H049.
2 -   Verify that system total static pressure and airow 
settings are within specic operating parameters.
The  following  repair  parts  are  available  through  Lennox  dealers.  When  ordering  parts,  include  the  complete  furnace 
model number listed on the CSA International nameplate -- Example: SLP99DF070V36B. All service must be done by 
a licensed professional installer (or equivalent), a service agency, or the gas supplier.
RepairParts List
Cabinet Parts
Outer access panel
Blower access panel
Top cap
Control Panel Parts
Transformer
SureLight® integrated control
Door interlock switch
Circuit breaker
Blower Parts
Blower wheel
Motor
Blower housing cut-o plate
Heating Parts
Flame Sensor
Heat exchanger assembly
Gas manifold
Combustion air inducer
Gas valve
Main burner cluster
Main burner orices
Pressure switches
Ignitor
Primary limit control
Flame rollout switches