Troubleshooting
Ignition Control Diagnostic LED
During normal operation, the LED is shut off. The LED will be on or flashing during a fault condition. If a fault condition is occurring, turn the unit off and on again. If the LED is still flashing, refer to the following troubleshooting section.
LED Indication | Error Mode |
Steady on | Internal control failure |
1 flash | Air flow fault |
2 flashes | Flame with no call for heat |
3 flashes | Ignition lockout |
|
|
Airflow Fault (1 Flash)
An airflow fault may occur for the following reasons:
•An airflow switch continually monitors the combustion airflow during an ignition sequence. During the initial call for heat, if the pressure switch contacts are in the closed position for 30 seconds without an output to the combustion blower, an airflow fault will be declared. The control will remain in this mode with the combustion blower off.
•After the combustion blower output (L1 and IND) is energized and the airflow switch remains open for more than 30 seconds, an airflow fault will be declared. The control will stay in this mode with the combustion blower on, waiting for the airflow switch to close.
•If the airflow signal is lost while the burner is firing, the control will immediately
Once proper airflow is detected, the normal Sequence Of Operation for ignition will follow (see page 4).
Flame Fault (2 Flashes)
If the main valve fails to close completely and maintains a flame, the
Ignition Lockout (3 Flashes)
Possible Cause | Solution |
Manual gas valve not open | Open manual valve |
Air in the gas line | Bleed gas line |
|
|
Supply gas pressure too high or too low | Check that supply pressure is between 6 in. wg and 14 in. wg for |
| natural gas and 11 in. wg and 14 in. wg for LP. |
|
|
Loose wire connections | Check for tight wire connections. |
No spark: |
|
a. Transformer failure | a. Check primary and secondary voltages of transformer. Replace |
| if necessary. |
b. Spark electrode | b. Ensure spark gap is 1⁄8 in. and ceramic insulator is not cracked. |
| Replace if necessary. Electrode is NOT |
c. Spark cable shorted to ground | c. Replace spark cable |
d. Ignition controller not grounded | d. Check that the ignition controller is grounded to the furnace |
| control center. |
High limit control tripped | Check unit airflow and manifold pressure. |
Faulty combination gas valve | If 24 volts is measured between terminals MV and common, but |
| valve remains closed, replace valve. |
|
|
Faulty ignition control | Check diagnostic LED for steady on and for voltage between V1 |
| and V2. If no voltage is present, replace ignition control. |
|
|
7