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between 90° − 110° at the instant the blower is de−ener-
gized. (Longer delay times allow for lower air temperature,
shorter delay times allow for higher air temperature). See
figure 7.
Board 100973−0
only has a 45 second fan off
delay after cooling demand is satisfied. This delay timing is
factory set and non adjustable.
The ignition control boards are equipped with two LED
lights for troubleshooting. The diagnostic codes are listed
in table 11.
FAN-OFF TIME ADJUSTMENT
To adjust fan−off timing, reposition jumper across pins to
achieve desired setting.
FIGURE 7
TABLE 11
DIAGNOSTIC CODES
Make sure to Identify LED’S Correctly.
Refer to figures 3 and 5 for control board layout.
LED #1
DS #1
AN #1
LED #2
DS #2
AN #2
DESCRIPTION
SIMULTANEOUS
SLOW FLASH
SIMULTANEOUS
SLOW FLASH
Power on − Normal operation.
Also signaled during cooling and continuous fan.
SIMULTANEOUS
FAST FLASH
SIMULTANEOUS
FAST FLASH
Normal operation − signaled when heating demand initiated at thermostat.
SLOW FLASH
ON
Primary or secondary limit switch open. Limit must close within 3 minutes or unit
goes into 1 hour Watchguard.
OFF
SLOW FLASH
Prove switch open.
OR: Blocked inlet/exhaust vent;
OR: Prove switch closed prior to activation of combustion air inducer.
ALTERNATING
SLOW FLASH
ALTERNATING
SLOW FLASH
Watchguard −− burners failed to ignite.
SLOW FLASH
OFF
Flame sensed without gas valve energized.
ON
SLOW FLASH
Rollout switch open. OR: 24V pin connector improperly attached.
ON
ON
ON
OFF
Circuit board failure or control wired incorrectly.
OFF
ON
y
FAST FLASH
SLOW FLASH
Main power polarity reversed. Switch line and neutral.
SLOW FLASH
FAST FLASH
Low flame signal. See Table 18 for flame sense.
ALTERNATING
FAST FLASH
ALTERNATING
FAST FLASH
The following conditions are sensed
Improper main ground (Control 56L84, 10M93, 32M88, 69M08) during ignitor
warm up period ONLY, improper main ground continuously (Control 78M47)
OR: Broken ignitor (Control 56L84, 10M93, 32M88, 69M08)
OR: Open ignitor circuit (Control 56L84, 10M93, 32M88, 69M08)
OR: Line voltage below 75V (Control 56L84, 10M93, 32M88, 69M08)
90V (Control 78M47 & 100973−01)
NOTE − Slow flash rate equals 1 Hz (one flash per second). Fast flash rate equals 3 Hz (three flashes per second).
FIGURE 8
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
DEMAND
CAI
GAS VALVE
ON
OFF
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ
ÉÉ
ÉÉÉÉÉÉÉÉÉÉ
IGNITOR*
15 Sec.
Pre −Purge
20 sec.
Ignitor Warm−up
*4 Sec.Trial
for Ignition
Post
Purge
5 SEC
Blower on time will be 45 seconds after gas valve is energized. Blower off time will depend on OFF TIME" Setting.
INDOOR BLOWER
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ
Blower On"
Delay
End of
Heat Demand
Blower
Off
Time
* Control 78M47 & 100973−01 will energize ignitor the first 3 seconds of the 4 second trial
56L84, 1 second, 32M88, 69M08 entire trial (4 sec)
