Thermo King 002008, Manual

Page: 117 / 155

117
Refrigeration Diagnosis
R
a
pid
c
y
c
li
ng be
twe
e
n C
ool
and H
eat
Uni
t c
ool
s
in
H
e
a
t
an
d D
e
fros
t
cy
cl
e
U
n
it
h
e
a
ts
in
R
e
fr
ig
er
a
ti
o
n
cy
cl
e
H
igh he
ad pre
ssu
re
Low he
ad pre
ssu
re
No he
ad pre
ssu
re
H
igh su
cti
on pr
ess
ure
Low su
cti
on pr
ess
ure
No su
ct
ion
pr
ess
ure
U
n
it
op
era
ti
ng
in
a
vac
uum
Re
cei
ve
r si
ght
g
la
ss e
m
p
ty
S
u
cti
o
n
l
in
e
fr
ost
in
g
b
ack
Una
b
le
to pump
do
wn sy
st
em
U
n
ab
le
t
o
p
u
ll v
a
c
u
u
m
i
n
lo
w
si
d
e
U
n
ab
le
t
o
h
o
ld
v
a
c
u
um
in
l
o
w
s
id
e
N
o
is
y
compre
ss
or
U
n
it n
o
t
re
fr
ig
e
ra
tin
g
U
n
it
no
t hea
ti
ng or de
fro
s
ti
ng
Sy
mpt
o
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
• Damper open
• • • Damper stuck closed
• Discharge service valve back seated