Troubleshooting: Continuous Fan Sequence of Operation
CONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION
MANUAL FAN SELECTION MADE AT THERMOSTAT.
AFTER 2 SECOND DELAY, INDOOR BLOWER IS
ENERGIZED ON CONTINUOUS FAN SPEED.
YES |
| YES |
|
|
|
YES
THERMOSTAT CALLS FOR FIRST STAGE COOL.
YES
INDOOR BLOWER RAMPS TO FIRST STAGE
COOLING SPEED AFTER A 2−SECOND DELAY.
FIRST−STAGE COOL DEMAND SATISFIED?
NO 
SECOND STAGE COOL DEMAND
INDOOR BLOWER RAMPS TO SECOND
STAGE COOL SPEED
SECOND STAGE COOL DEMAND SATISFIED?
YES
INDOOR BLOWER RAMPS DOWN TO FIRST STAGE
COOL SPEED.
THERMOSTAT CALLS FOR FIRST−STAGE HEAT.
YES
AFTER 45−SECOND DELAY, INDOOR BLOWER
SWITCHES TO LOW HEAT SPEED.
FIRST−STAGE HEAT DEMAND SATISFIED.
NO 
THERMOSTAT CALLS FOR SECOND−STAGE HEAT.
YES 
INDOOR BLOWER SWITCHES TO HIGH HEAT SPEED
AFTER 30−SECOND RECOGNITION PERIOD.
YES
SECOND−STAGE HEAT DEMAND SATISFIED.
YES
INDOOR BLOWER RAMPS DOWN TO LOW
HEAT SPEED.
YES
Repair Parts List
The following repair parts are available through Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA nameplate −− Example: G61MP−36B−045−1. All service must be performed by a licensed pro- fessional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Upper access panel
Blower access panel
Top Cap
Control Panel Parts
Transformer
Two−stage integrated control board Door interlock switch
Circuit Breaker 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 switches Ignitor
Primary limit control Secondary limit control Flame rollout switches Combustion air inducer auxiliary limit
Page 62
