Honeywell 7800 Series Product Data page 16

7800 SERIES S7800B DISPLAY MODULE
Table 4. Fault Message and Recommended Troubleshooting (continued) .
Fault Code
Fault 28 Pilot flame failure.
Pilot Flame Fail
Fault 29 Lockout interlock fault.
Lockout ILK
Fault 30 Running interlock fault.
Running ILK
Fault 31 Low fire interlock switch
Low Fire Sw. Off failure to close during Run.
Fault 32 Combustion airflow
Airflow Switch interlock fault.
Fault 33 Preignition interlock fault.
Preignition ILK
65-0219—1
System Failure
1. Check pilot valve wiring and operation. Correct any errors.
2. Check fuel supply.
3. Check pilot pressure and repeat pilot turn down test.
4. Check ignition transformer electrode, flame de-tector, flame
detector sighting, and flame amplifier.
5. If steps 1 through 4 are correct and the fault per-sists, replace the
relay module.
1. Check wiring, correct any errors.
2. Inspect the fan, assure that there is no blockage of the air intake
and that it is supplying air.
3. Assure that the Lockout Interlock switches are functioning properly
and that their contacts are free from contaminants.
4. Reset and sequence the 7800 to Prepurge (place the Run/Test
Switch into the Test position, if available). Measure the voltage
between terminal 7 and G (ground). 120 Vac should be present.
5. If steps 1 through 4 are correct and the fault per-sists, replace the
relay module.
1. Inspect the running interlocks (including the air flow switch) and its
connections.
2. Assure that the running interlocks (including the air flow switch) are
functioning properly and the con- tacts are free from contaminates.
3. Reset and sequence the 7800 to prepurge (place the Run/Test
Switch into the Test position, if available). Measure the voltage
between terminal 7 and G (ground). 120 Vac should be present.
4. If steps 1-3 are correct and the fault persists, re-place the relay
module.
1. Check wiring, correct any errors.
2. Reset and sequence the 7800.
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 in the Test position.
Adjust the Low Fire Switch while in this state to assure that it is
closing properly.
4. While in Run drive to Low Fire state, measure the voltage between
terminal 19 and G (ground). 120 Vac should be present. If not, the
switch adjustment is incorrect and/or the switch is defective and
needs replacement.
5. Reset and sequence the 7800. If 120 Vac was present between the
Low Fire Switch and terminal 19 and the fault still persists, replace
the relay module.
1. Check wiring, correct any errors.
2. Inspect the fan, assure that there is no blockage of the air intake
and that it is supplying air.
3. Assure that the Airflow Interlock switches are functioning properly
and that their contacts are free from contaminants.
4. Reset and sequence the 7800 to Prepurge (place the Run/Test
switch into the Test position, if available). Measure the voltage
between terminal 7 and G (ground). 120 Vac should be present.
5. If steps 1 through 4 are correct and the fault per-sists, replace the
relay module.
1. Check wiring, correct any errors.
2. Inspect the Preignition Interlock switches and assure that they
function properly.
3. Check fuel valve operation. Valve must close within five seconds.
4. Reset and sequence the 7800. During Standby or Prepurge,
measure the voltage between terminal 20 and G (ground). 120 Vac
should be present. If not, the Preignition Interlock switches may be
defective and need replacement.
5. If the fault persists, replace the relay module.
Recommended Troubleshooting
16
(continued)