Service manual

All installations and services must be performed by qualified service personnel.
39
Does the circulating air
blower turn off after
thermostat is satisfied
within 4 minutes?
Does burner shut off
when thermostat is
satisfied?
Has the high limit thermostat
or auxiliary high limit
thermostat activated?
Check all wiring for
loose connections.
Yes
Yes
Yes
Yes
No
No
Yes
No No
Check for reduced airflow through
the furnace. This may be caused
by an excessively restrictive duct
system, an inadequate amount of
supply air,especially for furnaces
installed in closets, or extremely
dirty air filters. Also, check and
confirm heat input rate to unit is
within specifications.
Does system run until
thermostat is satisfied?
Check fan timer settings
against those on connection
diagram. Is fan selector
switch set on "manual".
Reset if necessary. Does
fan still fail to turn off?
Replace fan timer.
Yes
Check for short in wire
to thermostat. Replace
thermostat, if necessary.
Troubleshooting Complete.