Submittal Sheet

7800 SERIES S7800A2142 KEYBOARD DISPLAY MODULE
32-00110—05 22
Fault 31
*Low Fire Sw. Off*
Low Fire Interlock Switch
failure to close during RUN
(Device specific).
1. Check wiring and correct any errors.
2. Reset and sequence the relay module.
3. Use either the manual motor position to drive the motor to
the Low Fire position, or use the Run/Test Switch option, if
available. Sequence to Run drive to Low Fire and place the
switch in the Test position. Adjust the Low Fire Switch while
in this state to make sure it is closing properly.
4. While in Run, drive to Low Fire state, measure the voltage
between terminal 18 and L2(N). Line voltage should be
present. If not, the switch adjustment is incorrect and/or
the switch is defective and needs replacement.
5. Reset and sequence the relay module. If line voltage was
present between the Low Fire Switch and terminal 18, and
the fault persists, replace the relay module.
Fault 32
*Airflow Switch*
Combustion Airflow Interlock
fault.
1. Check wiring and correct any errors.
2. Inspect the fan; make sure there is no blockage of the air
intake and it is supplying air.
3. Make sure the Airflow Interlock Switches are working prop-
erly and all switch contacts are free from contaminants.
4. Reset and sequence the relay module to PREPURGE. Place
the Run/Test Switch in the Test position, if available. Mea-
sure the voltage between terminals 7 and L2(N). Line volt-
age should be present.
5. If steps 1 through 4 are correct and the fault persists,
replace the relay module.
Fault 33
*Pre-Ignition ILK*
Pre-Ignition Interlock fault. 1. Check wiring and correct any errors.
2. Inspect the Pre-Ignition Interlock switches and make sure
they function properly.
3. Check fuel valve operation. Valve must close within five
seconds.
4. Reset and sequence the relay module.
5. During STANDBY or PREPURGE, measure the voltage
between terminal 20 and L2(N). Line voltage should be
present. If not, the Pre-Ignition Interlock switches can be
defective and need replacing.
6. If the fault persists, replace the relay module.
Fault 34
*Control On*
CTL input was energized at
the wrong time for the relay
module. This fault implies a
field wiring error.
1. Check wiring and correct any errors.
2. Reset and sequence the relay module.
3. If fault persists, replace the relay module.
Fault 35
*Call Service*
Safety relay was off when it
should be on or the internal
fuse has blown.
1. Reset and sequence the relay module. If fault repeats,
replace relay module, but be sure to test for excessive loads
on appropriate terminals described by fault code.
2. If fault does not repeat on next cycle, check for electrical
noise being coupled into the relay module through the
loads on appropriate terminals described by the fault code.
3. Possibly check for bouncing running on Lockout Interlock.
4. If fault persists, replace the relay module.
Fault 36
*Call Service*
Main valve terminal was off
when it should be on, or the
internal fuse has blown.
Fault 37
*Call Service*
Pilot (ignition) valve terminal
was off when it should be on,
or the internal fuse has
blown.
Fault 38
*Call Service*
Ignition terminal was off
when it should be on, or the
internal fuse has blown.
Fault 39
*Call Service*
V2S valve terminal (usually
terminal 21) was off when it
should be on, or the internal
fuse has blown.
Fault 40
*Call Service*
Safety relay was on when it
should be off.
Table 5. Fault Message Summary. (Continued)
Fault Code System Failure Recommended Troubleshooting