AAON M2-036 - Manual (Page 64)

64
Table 9 - Gas Heater Troubleshooting
LED
Code
System Description Actions
None No Power to
T1
On call for heat nothing happens 1. Check for open fuse or circuit breaker.
2. Check for poor wiring connection.
3. Check for failed 24V transformer.
Open Limit
Switch
Thermostat call for heat. No power
across terminals V1 / V2 control.
1. Check for proper operation of circulating air
supply system and for air filter blockage.
2. Check manifold pressure when limit cools and
closes. Natural gas 3.5” w.c / LP gas 10.0” w.c.
3. Low combustion blower air output. Flue gas
temp exceeds 550ºF. Inspect for debris
accumulation, proper wheel attachment, and
proper voltage to blower.
Steady
On
Internal
Control Fault
(No Operation)
24VAC across Terminal 24VAC /
V2-Gnd when Thermostat calling for
heat
Control fault – Replace ignition control.
1
Flash
Combustion
Air Flow Fault
Pressure switch contacts in closed
position for 30 seconds with no
output to Combustion blower.
Remains in this mode with
combustion blower off.
1. Check for short in wiring to pressure switch.
2. Check pressure switch for closed contacts (with
leads disconnected).
3. Replace pressure switch
Open pressure switch or flame
rollout switch when inducer (IND
terminal) is energized. If switch
remains open for more than 30
seconds after combustion blower is
energized, control will remain in this
mode with IND terminal (blower)
energized.
1. Failed Combustion blower.
2. Check connections and air tube from draft
inducer to air switch for leaks.
3. Check rollout switch manual reset - depress
reset.
4. Check supply tube from draft inducer housing
to pressure switches for condensate - drain line
and re-connect.
5. Check pressure switch for condensate
accumulation
6. Replace pressure switch