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I−UNIT COMPONENTS
Unit components are shown in figure 1. The gas valve,
combustion air inducer and burners can be accessed by re-
moving the burner access panel. Electrical components
are in the control box (figure 2) found in the blower section.
CAUTION
Electrostatic discharge can affect electronic
components. Take precautions during furnace
installation and service to protect the furnace’s
electronic controls. Precautions will help to avoid
control exposure to electrostatic discharge by
putting the furnace, the control and the techni-
cian at the same electrostatic potential. Neutral-
ize electrostatic charge by touching hand and all
tools on an unpainted unit surface, such as the
gas valve or blower deck, before performing any
service procedure.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
1. Control Transformer (T1)
A transformer located in the control box provides power to
the low voltage section of the unit. Transformers on all
models are rated 40VA with a 120V primary and a 24V sec-
ondary.
2. Door Interlock Switch (S51)
A door interlock switch rated 14A at 125VAC is wired in se-
ries with line voltage. When the blower door is removed the
unit will shut down.
FIGURE 2
CONTROL BOX G60DFV
Transformer
SureLighttTwo−Stage
Integrated Control Board
Door
Interlock Switch
Circuit
Breaker
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box.
The switch provides overcurrent protection to the trans-
former (T1). The breaker is rated 3A at 32V. If the current
exceeds this limit the breaker will trip and all unit opera-
tion will shutdown. The breaker can be manually reset
by pressing the button on the face. See figure 3.
FIGURE 3
CIRCUIT BREAKER CB8
PRESS TO RESET
WARNING
Shock hazard.
Disconnect power before servicing. Integrated
Control Board is not field repairable. If control is
inoperable, simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
4. Integrated Control Board (A92)
Board 18M99
G60DFV units are equipped with the Lennox two−stage,
variable speed integrated SureLight control board. The
system consists of a ignition / blower control board (figure
4 with control terminal designations in tables 1 through 4)
and ignitor (figure 12). The board and ignitor work in com-
bination to ensure furnace ignition and ignitor durability.
The SureLight integrated board controls all major furnace
operations. The board features two LED lights, DS1 and
DS2 for troubleshooting and four LED lights (DS3, DS6,
DS7 and DS8) to show furnace status. The board also has
two accessory terminals rated at (1) one amp each. See
table 5 for status code and table 6 for troubleshooting
diagnostic codes.
Electronic Ignition
At the beginning of each heating cycle, the SureLight con-
trol monitors the first stage and second stage combustion
air inducer prove switch. The control will not begin the heat-
ing cycle if the first stage prove switch is closed (by−
passed). Likewise the control will not begin the second
stage heating cycle if the second stage prove switch is
closed, and will allow first stage heat only. However if the
second stage prove switch closes during the first stage pre−
purge, the control WILL respond to second stage heat call.
Once the first stage prove switch is determined to be open,
the combustion air inducer is energized on low (first stage)
heat speed. When the differential in the prove switch is
great enough, the prove switch closes and a 15−second
pre−purge begins. If the switch is not proven within 2−1/2
minutes, the control goes into Watchguard−Pressure
Switch mode for a 5−minute re−set period.
