Ingersoll-Rand M952V060BD36AB, Service Facts

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32
Service Facts
M952-SF-4
Cycle power to
furnace and call
for heat
Ignition occurs and
FAN ON delay
begins
Does fan come
on after ~45
seconds?
Does blower
wheel turn
freely?
Disconnect
electrical power to
furnace
YES
Check set screw
position and motor
bearings. Correct
or replace as
needed.
Check operation
NO
YES
Is 120 VAC
measured at IFC
between CIR-H and
CIR-N?
NO
Repair wiring harness.
Check operation
Are filter &
blower wheel
clean?
YES
Replace filter and
clean blower
wheel.
Check operation
NO
Is external
static pressure
greater than
nameplate?
YES
Correct application
or duct issues.
Check operation
YES
Is heat rise
within
specification?
See Service
Facts
NO
Is return air
temperature
above 85 F?
NO
Return air
temperature is
above max limit
YES
Check for loose
insulation or other
objects within
furnace air stream
NO
Is outlet
manifold gas
pressure within
specifications?
YES
Correct gas
pressure
Check operation
NO
Is temperature at
high limit above
the switch setting?
YES
Replace high limit
switch
NO
YES
Is temperature at
reverse flow
switch above
specifications?
Replace reverse
flow switch
NO
Check for excessive
reverse flow during an off
cycle
YES
DEFINITION
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
left jumpered when not
troubleshooting.
Make sure any temperature
measuring devices
(thermocouples, dial
thermometers) used to
estimate limit temperature
are within ¼ inch of limit
measurement point
See next page for
additional 4 flash
faults
4 Flash Fault LED
NO
YES
NO
Does motor
continue to run
during the entire
heating cycle?
YES
High voltage should
always be present.
Check wiring.
See ECM motor check out in
Service Facts.
YES
NO
Note:
Furnace will need to be checked
in both 1
st
& 2
nd
stage operation.
Is 120 VAC measured
at motor between
terminals
4 (WH/7) & 5 (BK/8)?
Down Flow Models Only
Reverse flow switch
checkout