Thermo King SB-210, Manual

Page: 141 / 159

141
Refrigeration Diagnosis
R
api
d
cy
c
ling be
tw
e
en c
o
o
l
a
nd h
eat
U
n
it
c
o
ol
s
i
n
h
e
a
t
an
d
de
fr
os
t c
y
c
le
Un
it
h
e
a
ts in
r
e
fr
ig
e
ra
tio
n
c
ycle
H
igh h
ead
p
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s
s
u
re
Lo
w h
ead
p
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s
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re
H
igh s
u
c
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on p
res
s
u
re
L
o
w
su
ctio
n
pr
e
ssu
re
N
o
su
c
ti
o
n pr
es
su
re
Un
it
o
p
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ra
tin
g
in
a
va
cu
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m
R
e
c
e
iv
er
s
igh
t g
las
s
e
m
pt
y
S
u
c
ti
on l
in
e fr
os
ti
ng ba
c
k
U
nab
le
t
o
pu
mp do
wn
s
y
s
te
m
Un
a
b
le
to
p
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ll
va
cu
u
m
in
lo
w
sid
e
Un
a
b
le
to
h
o
ld
v
a
c
u
u
m
in
lo
w
sid
e
No
isy
co
m
p
re
s
s
o
r
Un
it n
o
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fr
ig
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ra
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it
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t hea
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ng or
def
ro
s
ti
n
g
Sy
mp
to
m
Possible Causes
• • • • Overcharge of refrigerant
• • • • • • Shortage of refrigerant
• • • • • No refrigerant
• Air through condenser too hot (ambient)
• Air flow through condenser restricted
• • • Air through condenser too cold (ambient)
• • • Air in refrigerant system
• Condenser fan blades bent or broken
• Air short cycling around evaporator coil
• Air through evaporator restricted
• • • • Evaporator needs defrosting
• • Compressor discharge valves leaking
• • Compressor suction valves leaking
• Too much compressor oil in system
• Faulty oil pump in compressor
• Faulty compressor drive coupling
• Compressor bearing loose or burned out
• • • • • Broken valve plate in compressor
• • Expansion valve power element lost its charge
• • Expansion valve feeler bulb improperly mounted
• • • Expansion valve feeler bulb making poor contact
• • Expansion valve open too much
• • Expansion valve closed too much
• • Expansion valve needle eroded or leaking
• • • Expansion valve partially closed by ice, dirt or wax
• • • Liquid refrigerant entering compressor
• • Restricted line on the low side
• • • • Restricted line on the high side
• • • • Restricted drier
• Defrost damper stays open
• • • Defrost damper stuck closed
• Suction service valve back seated
• • • • • • • • Faulty three-way valve
• • • • • Faulty pilot solenoid