Lennox 80MGF Series Manual page 13

Troubleshooting
The EGC control board is equipped with two diagnostic green
LEDs to indicate the mode of failure. The LED lights are
marked DIAG #1 and DIAG #2. The codes are given in table
4. On the EGC−1 only, the last failure code is stored in
memory and may be retrieved by depressing and holding
the memory recall button. When this button is depressed,
the LEDs will signal the last failure code in memory. Power
must be restored to the control (depress blower interlock
switch) within one minute of blower access panel removal in
order to retain memory. To clear the memory of the stored
failure code, remove main power and short the jumper next
to the diagnostic button for five seconds.
* NOTE: EGC−1 board will have terminal (#15) for
ACB low speed.
* * NOTE: EGC−1 board will have terminal
(#16) for ACB Heat speed.
DIAGNOSTIC MODULE
EGC−2 INTEGRATED CON-
7
6
5
4
DIAGNOSTIC LEDS
BLOWER TIME
ADJUSTMENT
JUMPER
THERMOSTAT
TERMINAL STRIP
(DETACHABLE)
EDGE
CONNECTION
24VAC
RED DIAGNOSTIC BUTTON
PLUG P20
(EGC−1 only. Depress button and hold
for display of last failure code.)
DIAG #2
Simultaneous Simultaneous
Flash
On
Flash
Alternate
Alternate Flash
Flash
Off
Flash
Continuous
Continuous On
On
TROL
8 9 10 11 12 13
1 4 7
2 8
5
3 6 9
FIGURE 8
Page 13
TABLE 4
EGC DIAGNOSTIC CODES
DIAG #1 DIagnostic Condition
Power ON". Normal Operation. In-
creased flash rate indicates there
Flash
is a heating demand.
Primary or Secondary
Flash Limit Switch Open.
Auto-Reset Switch.
Pressure Switch Watchguard,
pressure switch opened during
Off
operation or condensate
drain blocked.
Watchguard, burners
failed to ignite.
Flame sensed without
Flash
valve energized.
Roll-out Switch Open.
On
Manual-Reset Switch.
Circuit board self-check failure or
ignition/blower control
is wired incorrectly.
*
* *
14 15
16
3 2
DIAGNOSTIC CODE ERASE JUMPER
(Remove power to control and short pins for
10 seconds to erase previous code.)
1