Lennox 80MGF Series Manual page 14

TABLE 5
BLOWER CONTROL A15 TERMINAL DESIGNATIONS
Terminal
Designation Type
(See fig. 8)
R Screw Strip
G Screw Strip
W Screw Strip
Y Screw Strip
C Screw Strip
1 1/4" Spade
2 1/4" Spade
3 1/4" Spade
4, 5, 6 1/4" Spade
7 1/4" Spade
8 1/4" Spade
9 1/4" Spade
10 1/4" Spade
11 1/4" Spade
12, 13 1/4" Spade
14 1/4" Spade
15 1/4" Spade
16 1/4" Spade
TABLE 6
EGC CONTROL JACK/PLUG 20 TERMINAL DESIGNATIONS
Pin #
1
2
3
4 Pressure Switch Return
5 Hi Limit Return / Pressure Switch Out
6
7
8
9
DANGER
Shock hazard.
Disconnect power before servicing. Control 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.
Function
24VAC to Thermostat (Red)
Manual Fan Input from Thermostat
(Green)
Heat Demand Input from Thermostat
(White)
Cool Demand Input from Thermostat
(Yellow)
Common Ground to Thermostat
24VAC Hot from Transformer
24VAC Return to Transformer
24VAC Ground
120VAC Return − 120VAC Common
120VAC Return − 120VAC Common
Input
Combustion Blower (Line Voltage)
Heat Only Accessory (Line Voltage)
120VAC Hot to Transformer
120VAC Hot Input
Accessories (Line Voltage)
ACB Cool Speed (Line Voltage)
EGC−1 ACB Low Cont. Speed
(Line Voltage)
EGC−2 ACB Heat Speed
(Line Voltage)
ACB Heat Speed (Line Voltage)
Function
Rollout Switch Out
Spare
Gas Valve Common
Flame Sensor
Gas Valve Out
High Limit Out
Rollout Switch Return
5−Flame Sensor (−11 models)
A flame sensor is located on the left side of the burner sup-
port. See figure 9. The sensor is mounted on a bracket in
the burner support and the tip protrudes into the flame en-
velope of the left−most burner. The sensor is fastened to
burner supports and can be removed for service without
removing any part of the burners. During operation, flame
is sensed by current passed through the flame and sens-
ing electrode. The SureLight control allows the gas valve
to remain open as long as flame signal is sensed.
NORMAL FLAME SIGNAL u 0.7 MICROAMPS
LOW FLAME SIGNAL
MINIMUM FLAME SIGNAL v 0.15 MICROAMPS
1/4 in. 7 mm
 1/32 in. 0.79
BURNER
SIDE VIEW
NOTE − The 80MGF furnace contains electronic com-
ponents that are polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.
6− SureLight Ignition System A3
(−11 models)
All 80MGF−11 model units are equipped with the Lennox
SureLight ignition system. The system consists of ignition
control board (figure 11 with control terminal designa-
tions in table 10) and ignitor (figure 12). The board and ig-
nitor work in combination to ensure furnace ignition and
ignitor durability. The SureLight integrated board controls
all major furnace operations. The board also features two
LED lights for troubleshooting and two accessory termi-
nals rated at (4) four amps. See table 9 for troubleshoot-
ing diagnostic codes. Table 7 and 8 show jack plug termi-
nal designations. Units equipped with the SureLight
board can be used with either electronic or electro−me-
chanical thermostats without modification. The SureLight
ignitor is made of durable silicon−nitride. Ignitor longevity
is also enhanced by voltage ramping by the control board.
The board finds the lowest ignitor temperature which will
successfully light the burner, thus increasing the life of the
ignitor.
Page 14
v 0.7 MICROAMPS
11/16 in. 18 mm
 1/32 in. 0.79
mm
3/16 in.
4.7 mm
FLAME
SENSOR
END VIEW
FIGURE 9
mm