5.0
Maintenance
•
Troubleshooting Guide
LS
Series
40
5.0
Maintenance
Is the blower
obstructed?
Replace circuit board.
Does the ignitor warm
up and glow red?
Is the ignitor
physically
damaged?
Check voltage at ignitor during
ignition sequence (usually 5 to
15 seconds after power to the
heater). Is it 120V?
Is the inlet or the outlet of
the unit obstructed (i.e.,
ice, birds nest, dirt, etc.)?
Turn up thermostat
Does the fan
blower turn on?
Is the power at the
heater 120V?
Find the source of the electrical
problem between panel and heater.
No
Yes
Remove obstruction
and lubricate fan.
No
Yes
Does the switch
light energize?
Yes
Is the light burnt out?
If so, replace.
No
No
Yes
Remove obstruction.
No
No
No
No
Yes
Yes
Replace ignitor.
Does valve light
energize?
Yes
Does the burner
ignite at all?
No
The circuit board and/or wiring
harness may be faulty and
needs to be replaced.
No
Yes
Replace faulty light.
Does valve open?
Yes
Confirm that gas pressure
is within minimum and
maximum inputs as
indicated on the burner
rating plate. Are they ok?
Correct problem.
No
Replace gas valve.
Yes
Yes
Continued on page 42.
No
No
Yes