CTHN-S
ERIES
I
NSTALLATION
, O
PERATION
AND
S
ERVICE
M
ANUAL
80 of 91
Troubleshooting Flow Chart - Unitary (continued)
Chec
k f
o
r the pr
oper
or
if
ice and air plat
e
inside the
b
ur
ner
.
A
djust the
v
al
v
e
pr
essur
e
.
Is the g
as outlet pr
essur
e
3.5" f
o
r
N
atur
al Gas
(1
0.5" f
or LP)?
P
u
rge Lines
.
Is ther
e g
as outlet
pr
essur
e
a
v
aila
b
le dur
ing
the ignition per
iod?
Measur
e
v
olt
age on
v
al
v
e
te
rm
inals
. Is ther
e
24
V
dur
ing ignition per
iod?
R
eplace g
as
v
al
v
e.
(
N
atur
al P/
N
90032500)
(LP P/
N
90032502)
Is the kno
b
on the g
a
s
v
al
v
e in the on position.
Ar
e the w
ir
es connecting
the ignition module OK?
Tu
rn
v
al
v
e on.
N
o
N
o
Ye
s
Y
e
s
Ye
s
N
o
Ye
s
Ye
s
N
o
N
o
N
o
Ye
s
N
o
Ye
s
W
er
e the g
a
s lines
pur
g
ed of air?
Is the inlet g
a
s pr
essur
e
dur
ing ignition corr
ect?
(
N
atur
al 4.6" min, 5.0 f
o
r
E
V
-1
75, -200,
LP should
b
e 1
1.0" min)
Chec
k g
as line st
op
coc
k.
C
ont
act g
a
s
compan
y.
R
e
place ignition module
.
(P/
N
90434002K)
R
eplace/C
orr
ect w
ir
e
s
.
Ye
s
R
e
place door
.
Does the
b
ur
ner light?
N
o
Ye
s