Specification Sheet

7800 SERIESS7800A2142 4Line LCD Keyboard Display Module
320011007 20
Fault Code System Failure
Fault 19
*Main Flame
Ignition*
Flame was lost during
MFEP or the first 10
seconds of the RUN
state.
Inspect the main fuel valve(s) and connection(s).
Make sure that the fuel pressure is high enough to supply fuel
to the combustion chamber.
Make sure the flame detector is positioned to obtain the
required flame signal strength; reset and recycle.
Fault 20
*Low Fire
Switch Off*
Low Fire Interlock
switch failure to close
during PREPURGE.
Check wiring and correct any errors.
Reset and sequence the relay module.
Use either the manual motor potentiometer to drive the motor
to the Low Fire position or use the Run/Test Switch option, if
available. Sequence to Prepurge drive to Low Fire and place in
the Test position. Adjust the Low Fire Switch to make sure that
it closes properly.
Measure the voltage between terminal 18 and G (ground)
while in the Prepurge drive to Low Fire state. Line supply
voltage should be present. If not, the switch adjustment is
incorrect and/or the switch is defective and needs replacing.
Reset and sequence the relay module. If line supply voltage
was present between the Low Fire Switch and terminal 18,
and the fault still persists, replace the relay module.
Fault 21
*Running
ILK*
Running Interlock fault
during PREPURGE.
Check wiring; correct any errors.
Inspect the fan; make sure there is no blockage of the air
intake and that it is supplying air.
Make sure the Interlock Switches are working properly and
that all switch contacts are free of contaminants.
Reset and sequence the relay module to PREPURGE (place
the
Run/Test Switch in the Test position, if available). Measure
the voltage between terminals 7 and G (ground). Line voltage
should be present.
If steps 1 through 4 are correct and the fault persists, replace
the relay module.
Fault 22
*Lockout
ILK*
Lockout Interlock fault
during PREPURGE.
-
Fault 23 *Air-
flow Switch*
Combustion airflow
interlock fault during
PREPURGE.
-
Fault 24 *In-
ternal fault*
The flame interlock
(relay module) was on
when it should be off.
Check for F leadwire routing. Make sure routing is in its con-
duit and isolated from noise-producing circuits.
Fault 25 *In-
ternal fault*
The flame interlock
(relay module) was off
when it should be on.
Fault 26
*Man-Open
Sw. Off*
The Manual Open
Valve Switch was off
when it should be on
(RM7838B only).
Check wiring and correct any errors.
Make sure that the Manual Open Valve Switch is fully open.
Make sure that the Manual Open Valve Switch is functioning
properly and that the switch contacts are free from contam-
inants.
Reset and sequence the relay module.
Make sure that the Manual Open Valve Switch provides an
electrical path when closed. Verify that the relay module is
receiving power at terminal 17.
If steps 1 through 5 are correct and the fault persists, replace
the relay module.