T
w
o Times
D
if
fe
re
n
ti
a
l
a
ir
p
re
s
s
u
re
s
w
it
c
h
c
o
n
ta
c
ts
h
a
v
e
n
o
t
c
lo
s
e
d
.
In
d
ic
a
te
s
n
o
a
ir
p
ro
v
in
g
i
n
f
a
n
s
e
c
ti
o
n
o
f
h
e
a
te
r
Is
pressure switch
stuck open? Check
continuity
.
Ye
s
No
Is
fa
n loose on
mo
to
r shaf
t?
Ye
s
Tight
e
n f
a
n blade set scre
w
Is
pr
oper
v
o
ltage supplied
to
f
a
n mo
to
r?
No
Ye
s
Def
e
ctiv
e mo
to
r.
R
e
place mo
to
r
Is
ignition module
receiving pr
oper
vo
lt
a
g
e
?
No
Def
e
ctiv
e ignition module.
R
e
place module.
Ye
s
Def
e
ctiv
e wiring or
connections t
o
mo
to
r.
R
e
pair or replace
wiring and connections
No
Pr
o
v
ide pr
oper v
o
ltage.
Check electrical supply
,
cir
c
uit break
e
rs
, etc.
Is
pr
oper
v
o
ltage supplied
to
h
e
a
te
r?
Ye
s
No
R
e
d
L
E
D
F
la
s
h
in
g
One Time
D
if
fe
re
n
ti
a
l
a
ir
p
e
s
s
u
re
s
w
it
c
h
c
o
n
ta
c
ts
a
re
c
lo
s
e
d
b
e
fo
re
f
a
n
m
o
to
r
s
ta
rt
s
.
Is pressure switch
stuck closed?
Check continuity
.
Ye
s
No
R
e
place air
-pr
o
v
ing switch
Def
e
ctiv
e wire or loose
connection
to
air pressure switch. R
e
pair
as needed
Ensure copper or clear pressure switch
tubes are no
t plugged or kink
ed.
Check dif
ferential air pressure orif
ices.
If plugged, clean with air pressure.
Pressure switch out of calibration,
replace pressure switch.
25
Is
burner bo
x
gask
eting t
o
rn, or
missing?
No
Ye
s
R
e
place burner bo
x
gask
eting. ensure pr
oper
sealing of all burner bo
x
com
p
ar
tments.
No
