AAON M2-036 - Manual (Page 65)

65
Table 10 - Gas Heater Troubleshooting Continued
LED
Code
System Description Actions
2
Flash
Flame Fault
(No Call for
Heat)
Flame sense failure / flame present
with no call for heat.
1. Check for voltage to gas valve with thermostat
in off position. Valve should not be powered.
2. If valve is not energized, check for gas flow
(manifold pressure reading greater than 0). If gas
flow, turn off main shut-off valve and replace gas
valve.
3
Flash
Ignition
Lockout
Failure to light and or carryover.
Loss of flame or flame signal during
ignition or operation cycle.
Control will initiate up to 3 ignition
re-trials before lockout.
1. Verify gas supply available and operation of
gas valve - manifold pressure at start of ignition
cycle. Check for power to valve terminals LO &
COM while spark is energized.
2. Is spark present? - If not check igniter for debris
between electrodes, cracked ceramic and check
ignition wire for short to ground.
3. Check flame sensor wiring connections to
electrode and control and for any abrasions.
4. Check for cracked ceramic on flame sensor or
grounded sensor rod.
5. Verify that ample air supply and proper venting
of flue gases occurs during operating cycle.
6. Check for circulating air leaks into burner
compartment during operation.
7. Check for re-circulation of flue gases into
combustion air supply.
8. If all conditions satisfactory – replace ignition
control.