SERVICE AND TECHNICAL SUPPORT MANUAL
Gas Furnace: (F/G)9MXT
Specifications subject to change without notice.
23
440 04 4321 02
Figure 16 (CONT.) Troubleshooting Guide
1 +
2
B
LO
WE
R
ON AF
TE
R
PO
WE
R
UP
–
(
11
5V
O
R
24V
)
–
No
rm
al o
p
e
rati
on.
B
lower
r
u
ns f
o
r
90
se
c
o
n
d
s
,
if
u
n
it is
p
ow
er
ed
u
p
duri
ng a
c
a
ll
fo
r hea
t
(R
-
W
/
W
1 closed
)
or whe
n
(R
-
W
/
W
1 o
p
ens
)
duri
ng
the
bl
o
w
e
r o
n
-dela
y
p
erio
d.
6 + 1
IG
N
IT
I
ON LOCK
OU
T
–
S
y
s
te
m fa
iled
to
ignite
g
a
s a
nd
p
rove
flam
e i
n
4
attem
p
ts. C
o
n
trol
w
ill
a
u
to
-re
s
e
t a
ft
e
r 3
hou
rs.
R
ef
er
to s
tat
us c
o
d
e
#
6
.
5 A
B
NO
R
MA
L
F
L
A
M
E
-P
R
OV
I
N
G
SI
G
N
AL
F
lam
e is
p
ro
v
ed
while
gas
valv
e is
de
-
ene
rgi
zed.
I
ndu
cer
w
ill
r
un
until
fa
ult is
clear
e
d
. C
heck
fo
r:
-
S
tuck
o
p
e
n
or l
eak
y
ga
s val
ve.
2 P
RESS
U
RE
SW
IT
CH
DI
D
NO
T
OP
E
N
–
Check
fo
r:
- Obst
ruct
ed
p
ress
ur
e tu
be.
-
P
re
s
su
re
sw
it
ch
s
tu
c
k c
lo
s
ed
.
3 LO
W
-H
E
A
T
P
RE
SS
U
RE
SW
IT
CH
DI
D
NO
T
CLO
SE
O
R
RE
OP
E
N
ED
–
I
f o
p
en
s
duri
ng blo
wer on
-de
la
y
p
er
io
d
,
b
low
er
w
ill
com
e o
n
f
o
r t
h
e
se
le
cte
d b
lo
w
e
r
off-
del
a
y
.
I
f o
p
en
lon
ge
r t
h
a
n
5 m
in
u
te
s in
duc
er
shuts
o
ff fo
r 1
5
m
in
u
te
s
b
e
fo
re
ret
ry
.
Check
fo
r:
- P
ro
p
er v
e
n
t si
z
in
g
.
-
A
ir leak
b
e
tw
e
e
n
vesti
bul
e a
n
d
blo
we
r
com
p
a
rtm
ent
.
-
Lo
w
i
n
let
ga
s
p
ress
ur
e
(
if
L
G
P
S
us
ed
)
.
-
D
iscon
nec
ted
o
r o
b
str
uct
ed
p
ressu
re
tubi
ng.
-
D
efec
tive or
m
is
w
ir
e
d
p
ress
ur
e s
w
it
ch
e
s
-
E
x
c
e
ssiv
e
w
in
d
.
- P
lu
g
g
ed
con
de
nsa
te
dr
ain
-
W
ater in
ve
nt
p
i
p
in
g
,
p
ossi
ble s
a
g
g
in
g
p
i
p
e
-
R
estri
cte
d
ve
nt.
-
D
efec
tive
I
nd
uc
er m
o
to
r.
-
Lo
w
i
n
d
u
ce
r vol
tag
e
(
11
5 VAC
)
4 L
I
M
IT
C
IR
CU
IT
FA
U
L
T
–
I
n
dica
te
s th
e
lim
it
,
flam
e r
o
llo
ut
is o
p
en.
B
lo
wer w
ill
r
un
for 4
m
in. or un
til
o
p
en
s
w
itc
h r
e
m
a
k
e
s
which
eve
r is l
ong
er
.
I
f o
p
en
lon
ge
r t
h
a
n
3
mi
n
,
co
d
e
c
h
a
n
g
e
s t
o
lock
ou
t #
7
.
I
f o
p
en
less t
han
3 m
in
. st
atus
co
de
#4
con
tin
u
e
s
to fla
sh
until
blo
wer
sh
uts
off.
Fl
am
e
roll
o
u
t s
w
it
ch
re
qui
res m
a
nu
al r
e
se
t.
Check
fo
r:
-
Loo
se blo
wer whe
el.
-
D
efec
tive
s
w
itch
o
r co
nn
ectio
ns.
-
D
irt
y
filt
er
o
r r
e
str
ic
te
d d
u
ct s
y
ste
m
.
-
I
m
p
ro
p
er
g
a
s in
p
ut
a
d
justm
e
n
t
-
I
m
p
ro
p
er
lim
it s
w
itc
h o
r n
o
lim
it g
a
sk
et.
Un
p
lu
g ig
nit
er
har
ne
ss f
rom
co
nt
rol
and
re
p
eat
com
p
on
ent
tes
t. C
heck
fo
r 1
1
5
V
bet
wee
n
co
nn
ect
or P
2
(
H
SI
)
an
d
N
E
U
TR
AL
-L
2
o
n
t
he c
ont
rol
.
W
as 115
V
p
res
en
t
fo
r
the 15 sec
on
d
p
eri
od?
Check
co
nn
ectio
ns
and
r
e
tr
y
.
I
f cu
rr
ent
i
s
n
ear
t
y
p
ical v
a
lu
e
(
4.
0
-6
.
0
A
D
C
nom
in
al
)
an
d
bur
ne
rs
w
ill
not
sta
y
o
n
,
re
p
eat
ch
eck
in hi
gh
-he
at.
I
f
bur
ne
rs
w
ill s
till n
o
t st
a
y
on
re
p
lace
co
ntr
ol.
I
f b
u
rn
e
rs
o
p
e
rat
e in
hi
gh
-h
ea
t th
en
sw
it
ch t
o
l
o
w
-h
e
a
t
,
c
h
eck
m
a
nifol
d
p
ress
ur
e.
I
f OK
,
check
bu
rn
er
car
ry
o
v
e
r a
nd
flam
e se
ns
or l
o
cati
on.
Clean
flam
e
se
nso
r
w
it
h
fin
e st
eel
wool
and
r
e
che
ck
curr
en
t. N
o
m
inal
cur
re
nt i
s
4.
0
to 6.
0
A
D
C.
I
s
cu
rre
nt
ne
ar
ty
p
ic
al v
a
lue
?
R
e
p
la
ce elect
ro
de.
W
ill
m
a
in bur
ner
s ig
nite
an
d st
a
y
on
?
R
e
p
la
ce f
u
rn
ac
e c
o
nt
rol.
Fi
x
e
d.
YE
S
YE
S
NO
NO
R
e
p
la
ce f
u
rn
ac
e c
o
nt
rol.
Check
fo
r co
nti
nuit
y
i
n
t
h
e
har
nes
s
a
n
d i
gnit
er.
R
e
p
lac
e
def
ective
com
p
on
ent
.
R
eco
nn
ect t
he
R
th
erm
os
tat
lea
d
and
s
e
t
th
e
rm
o
sta
t to
ca
ll
fo
r h
e
a
t.
Co
nn
ect
voltm
ete
r acr
oss gas valv
e
co
nn
ecti
ons
.
D
oes
gas
valv
e r
e
c
e
ive
24V
?
D
oes gas
valv
e o
p
en
an
d a
llow
ga
s
to
flo
w
?
D
o th
e m
a
in
b
u
rner
s ig
nite
?
D
o th
e m
a
in
b
u
rner
s st
a
y
o
n?
A
llo
w blo
wer
to
com
e
on
an
d
re
p
eat
tes
t t
o
ch
eck
for
interm
itt
e
n
t o
p
e
rati
on.
Che
ck
co
nn
ectio
ns.
I
f OK
,
re
p
lace
co
ntr
ol.
Check
fo
r:
-
I
na
deq
ua
te fl
am
e c
a
rr
y
ov
er
or rou
gh
igni
tion
.
- Lo
w
i
n
let
ga
s
p
ress
ur
e.
- Pro
p
er firin
g
ra
te
.
R
e
p
e
a
t c
a
ll f
o
r
he
at
and
ch
eck
flam
e
sens
or c
u
rr
e
n
t
duri
ng
trial
fo
r ig
nitio
n
p
eri
od.
I
s t
h
e
D
C
c
u
rr
en
t b
e
lo
w
0
.5
A
?
YE
S
YE
S
YE
S
YE
S
YE
S
NO
NO
NO
NO
NO
NO
6
IG
N
IT
I
ON P
R
OV
I
N
G
FA
I
LU
RE
–
I
f f
lame
i
s
not s
e
n
s
ed
d
u
rin
g t
he
trial
fo
r ig
nitio
n
p
eri
od
,
th
e c
ont
rol
w
ill
re
p
e
at t
he i
gniti
o
n
seq
uen
ce
3 m
o
re
tim
es
be
fo
re l
o
ck
out
#
6 +
1 occ
urs
.
I
f flam
e
sig
nal is
lost
du
rin
g t
he
blo
w
e
r on-
del
a
y
p
eri
o
d
,
blo
wer
w
ill
c
o
m
e
o
n
for t
h
e
sel
ecte
d
blo
wer
off-
del
a
y
.
C
h
e
ck
th
e fo
llo
w
ing
b
e
fo
re
goin
g
to
t
he
ne
xt st
e
p
.
-
G
as v
a
lve
tu
rn
ed
off.
-
Man
ual
sh
ut-
off v
a
lve
o
p
en
?
-
G
re
en/
Y
e
llo
w wi
re
M
U
ST
be
c
o
n
nect
ed
to
f
u
rn
ace
sh
eet
m
e
ta
l.
-
Flam
e s
e
n
s
or
m
u
st
not
be
gr
ou
nd
ed.
9
H
IG
H-
H
E
A
T
P
RE
SS
U
RE
SW
IT
CH O
R
RE
LA
Y
DI
D
NO
T
CLO
SE
O
R
RE
OP
E
N
ED
- C
heck
fo
r:
-
C
o
nt
rol rel
a
y
m
a
y
be de
fectiv
e.
-
G
a
s
v
a
lve
is m
is
w
ir
ed.
-
R
efe
r t
o
st
atus
co
de
#3.
1
0
POL
A
RI
T
Y
–
Che
ck
for c
o
rr
ec
t lin
e
volta
ge
p
ol
arit
y
.
I
f u
n
its
are
t
w
in
ne
d
,
check
fo
r
p
ro
p
e
r lo
w
-volt
ag
e
(
24V
)
tra
nsfo
rm
er
p
h
asin
g.
7 L
I
M
IT
C
IR
CU
IT
LOCKOU
T
–
L
o
ck
out
occu
rs if
th
e lim
it or
flam
e
r
o
ll
out
is o
p
en
long
e
r tha
n
3
m
inut
e
s
.
Co
ntr
ol w
ill aut
o-
rese
t a
fte
r 3
ho
urs
.
R
efe
r t
o
st
atus
co
d
e
#4.
8
G
A
S
H
E
A
TI
N
G
L
O
CKOU
T
–
Co
ntr
ol
w
ill
NO
T
aut
o
res
et.
T
ur
n o
ff
p
o
w
e
r a
nd
wait
5 m
inut
es t
o
r
e
tr
y
. C
heck
f
o
r:
-
S
tu
ck
close
d g
a
s v
a
lve
r
e
la
y
on
con
tr
ol.
-
Mis
w
ir
e
o
r s
hor
t t
o
g
a
s v
a
lve
w
ire
.
YE
S
Check
th
at
gas
valv
e el
ectri
c
sw
it
ch is
tu
rn
ed
on.
R
e
p
lac
e
valv
e.
T
o det
e
rm
in
e
w
h
et
her
th
e
p
ro
blem
is i
n
the gas
valv
e
,
i
g
nit
er
,
or
flam
e
sen
so
r t
he
s
y
stem
c
an be o
p
er
ate
d in
com
p
one
nt
test m
o
de.
T
o c
h
eck
th
e ig
nite
r
,
rem
ov
e
the
R
th
er
m
o
s
tat
co
nne
ctio
n fr
om
th
e
cont
rol
,
r
e
set
p
o
wer
,
st
art
the
com
p
on
e
n
t
test.
D
o
es t
h
e i
g
nit
er
glo
w o
ran
ge
/w
hit
e
b
y
th
e
end
of
th
e 1
5
s
e
co
nd
warm
-u
p
p
eri
od
?
NO
YE
S
