Sterling TD User Manual
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Table 8B - Tubular Duct Furnace Troubleshooting with LED Indicator Assistance
No Cycling or appliance power or thermostat call for heat
since appliance failure has occured.
Line voltage power can cause product damage, severe
injury or death. Only a trained experienced service
technician should perform this trouble-shooting.
1. Check the system thermostat to make sure it is calling
for heat. (Do not cycle the thermostat on and off at this
time.)
Not
Applicable
Not
Applicable
1.
Line voltage on terminals 120 and C on
transformer.
2.
Low voltage (24V) on terminals 24 and C
on
transformer.
3.
5 Amp fuse on circuit board.
1. Common side of transformer grounded to
chassis.
2. Loose spark ignitor.
1. Gas supply off or gas supply pressure too
low.
2. Flame sense rod contaminated or loose
wire.
3. Gas valve switch is off or wires are not
connected.
4. Broken or cracked porcelain on fl ame probe
or spark ignitor.
1. Obstructions or restrictions in appliance air
intake or fl ue outlet are preventing proper
combustion airfl ow.
2. Moisture or debris in tubing that connects
pressure switch and draft inducer.
3.
Airfl ow switch jumpered or miswired.
1. Open manual reset rollout switch.
2.
Gas pressure too high, over fi re condition.
3.
Incorrect airfl ow due to blockage or motor
not
operating.
1. Flame probe miswired or shortened.
1. Thermostat is interfering with control board.
Control OK, no call for heat.
Control OK, call for heat present.
Internal control fault, or no power.
Control internal failure or bad ground.
In lockout from failed ignitions or fl ame losses.
Pressure Switch open with inducer on or
closed with inducer off.
Limit or rollout switch is open.
Flame sensed while gas valve is off.
On-board microprocessors disagree.
LED STATUS
INDICATES
CHECK/REPAIR
Slow Flash
Fast Flash
Steady Off
Steady On
2 Flashes
3 Flashes
4 Flashes
5 Flashes
6 Flashes
2. Remove the appliance burner compartment door. Do
not interrupt power to the control board by opening
any electrically interlocked panels.
3. Observe the LED indicator on the control board (a
greem LED labeled “OK” indicates system faults); check
and repair system as noted in the chart to the right.
*NOTICE: Air fl ow proving switch and power ventor
hose barbs must be free of any dust or debris at all
times. Periodically check these openings and/or if
any problems occur.