Troubleshooting 15
2. Field Maintenance
Possible causes of trouble
Po
w
er
fa
ilu
re
Bl
ow
n
fu
se
o
r v
ar
ist
or
Loo
se
c
onn
ec
�
on
s
Sh
or
te
d
or
b
ro
ke
n
w
ire
s
Sa
fe
ty
d
ev
ic
e
op
en
s
Fa
ul
ty
th
er
m
os
ta
t /
roo
m
te
m
pe
ra
tu
re
se
ns
or
W
ro
ng
se
�
ng
p
la
ce
o
f t
em
pe
ra
tu
re
se
ns
or
Fa
ul
ty
tr
an
sf
or
m
er
Sh
or
te
d
or
o
pe
n
ca
pa
ci
to
r
Fa
ul
ty
m
ag
ne
�
c
co
nt
ac
to
r f
or
c
om
pr
ess
or
Fa
ul
ty
m
ag
ne
�
c
co
nt
ac
to
r f
or
fa
n
Lo
w
v
ol
ta
ge
Fa
ul
ty
st
epp
in
g
m
ot
or
Sh
or
te
d
or
g
ro
und
ed
c
om
pr
ess
or
Sh
or
te
d
or
g
ro
und
ed
fa
n
m
ot
or
Unit will not start
Compressor will not start but fans run
Compressor and condenser (outdoor) fan will not start
Evaporator (indoor) fan will not start
Condenser (Outdoor) fan will not start
Unit runs, but shortly stops
Compressor short-cycles due to overload
High discharge pressure
Low discharge pressure
High suc
�
on pressure
Low suc
�
on pressure
Unit runs con
�
nuously but insu
ffi
cient cooling
Too cool
Compressor is noisy
Horizontal louver can not revolve
Test method / remedy
Te
st
v
ol
ta
ge
In
sp
ec
t f
us
e
ty
pe
&
si
ze
In
sp
ec
t c
onn
ec
�
on
s -
�
gh
te
n
Te
st
c
irc
ui
ts
w
ith
te
st
er
Te
st
c
on
�
nu
ity
o
f s
af
et
y
de
vi
ce
Te
st
c
on
�
nu
ity
o
f t
he
rm
os
ta
t /
se
ns
or
&
w
iri
ng
Pl
ac
e
th
e
te
m
pe
ra
tu
re
se
ns
or
a
t t
he
c
en
tr
al
o
f t
he
a
ir
in
le
t grille
Ch
ec
k
co
nt
ro
l c
irc
ui
t w
ith
te
st
er
Ch
ec
k
ca
pa
ci
to
r w
ith
te
st
er
Te
st
c
on
�
nu
ity
o
f c
oil
&
c
on
ta
ct
s
Te
st
c
on
�
nu
ity
o
f c
oil
&
c
on
ta
ct
s
Te
st
v
ol
ta
ge
Re
pl
ac
e
th
e
st
epp
in
g
m
ot
or
Ch
ec
k
re
sis
ta
nc
e
w
ith
m
ul
�
m
et
er
Ch
ec
k
re
sis
ta
nc
e
w
ith
m
ul
�
m
et
er
Electrical Circuit
