Trane S8V2A040M3PC Installation, Operation And Maintenance Manual page 65

Limit switches are safety devices
that will open when an abnormal
high temperature has been sensed.
REMOVE ALL JUMPER WIRING TO
SWITCHES!
Under no circumstances, shall these
switches be le jumpered when not
troubleshoo ng.
Verify filters and blower wheels are
clean
S8V2-SVX001-1A-EN
4.0 Fault Code
Main Thermal Limit
Make a call for 1 stage heat
Is 24 VAC
measured across
main thermal
Is external sta c
pressure greater
YES
than nameplate?
Correct applica on or
duct issues.
Check opera on
Is heat rise
specifica on?
See Nameplate
Is outlet
manifold gas
NO
pressure within
specifica ons?
Correct gas pressure
Check opera on
limit?
YES
Return air
temperature is
above max limit
YES
NO
Is return air
within
NO temperature
above 85 F?
YES
Is temperature at
YES high limit above the
switch se ng?
Replace high limit
switch
T T r r o o u u b b l l e e s s h h o o o o t t i i n n g g
Furnace will need to be checked
nd
in both 1 & 2 stage opera on.
Check for loose
insula on or other
NO
objects within
furnace air stream
YES
Make sure any temperature
measuring devices
(thermocouples, dial
thermometers) used to
es mate limit temperature are
NO
within ¼ inch of limit disc
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