L.B. White AW250(building controller) - Manual (Page 23)

23
Two Times Air proving switch do not 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
fan wheel loose
on mo
to
r
shaf
t?
Ye
s
Ye
s Ye
s
No
Check f
or binding of
flapper on housing. R
epair or replace as
necessar
y.
Ye
s
Ye
s
Check f
or pr
oper clearance
of f
an wheel t
o
mo
to
r
mount. If good, check f
o
r
housing alignment. If necessar
y replace f
an.
Tight
en f
an set scre
ws
securely t
o
flats of mo
to
r
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
.
Ye
s
R
emo
v
e
obstruction.
Clean as necessar
y.
No
Is
fan wheel
plugged with
dir
t? No
Is
there an
obstruction
in blo
w
er outlet
pre
v
enting air switch
closure?
No
Is
line 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, or replace ignition
contr
ol module.
No
Ye
s
Are
2
4
v
olts
sent t
o
air
pr
o
ving
switch?
Check wiring betw
een ignition
contr
ol module t
erminal PSI and
and air pr
o
ving switch. R
epair or
replace as necessar
y.
If wiring is
good replace ignition contr
ol.
No
No
With mo
tor in operation, check f
or 2
4
v
olts
fr
om t
erminal PSI and at t
erminal PSO 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
PSO, replace the air pr
o
ving switch.