L.B. White AD250 - Manual (Page 23)

T
w
o Times
Air pr
o
ving switc
h
contacts do no
t
close during a call for heat.
Are
air
-pr
o
ving switch
contacts stuck open?
(P
er
form continuity
check
.)
Does
fan mo
tor star
t up
for prepurge
during initial call
for heat?
Is
fan wheel
binding?
Is f
an wheel
loose on mo
to
r
shaf
t?
Ye
s
Ye
s
Ye
s
No
Check f
or binding of
air
-pr
o
ving switch arm
on housing, air
-pr
o
ving
flapper stuck, or out of adjustment. R
epair or
replace as necessar
y.
Ye
s
Ye
s
Check f
or pr
oper clearance of
fan wheel t
o
mo
tor mount. If
good, replace f
an wheel, or
check f
or housing alignment.
Tight
en set scre
w(s) on f
an.
Mak
e sure set scre
w(s) are
tight
ened against flat(s) of
mo
tor shaf
t.
Ye
s
Clean the f
an wheel with
com
pressed air or sof
t brush.
Def
ectiv
e mo
to
r
or capacit
or
.
R
eplace mo
to
r.
Ye
s
R
emo
v
e
obstruction.
Clean as necessar
y.
No
Is f
an wheel
plugged with
dir
t? No
Is there
an obstruction in blo
w
er outlet
pre
v
enting air
-pr
o
ving
switch closure?
Is
pr
oper v
oltage
supplied t
o
mo
to
r
fr
om ignition
module?
No
If im
pr
oper v
oltage is supplied,
contact electrician.
- OR -
If no v
oltage is supplied t
o
mo
to
r,
check wiring, and
connections. If good, replace
ignition contr
ol module. No
Ye
s
Is
pr
oper
v
oltage being
sent t
o
air
-pr
o
ving
switch?
Check f
or 2
4
v
olts fr
om
ignition contr
ol t
erminal PS1
to
air pr
o
ving switch. If absent.
check all electrical wiring. If
wiring is good, but 2
4
v
olts is
absent, replace ignition
contr
ol.
No
23
With mo
tor in operation, check f
or 2
4
v
olts
fr
om t
erminal PS1 and at t
erminal PS2 at
the contr
ol module. If 2
4
v
olts is sent fr
om
PSI, but no
t receiv
ed fr
om the air pr
o
vng
switch at PS2, replace the air pr
o
ving switch.
No No