Thermo King T-1000R, Maintenance Manual

Page: 270 / 282

Refrigeration System Diagnosis 15-2
Refrigeration Diagnosis
Ra
pid cyclin
g be
twee
n Cool an
d Heat
U
n
it
cools
in Heat
and D
e
frost c
ycle
U
n
it heat
s in R
e
frig
er
at
ion
(
C
oo
l)
cyc
le
Hig
h
he
ad pr
essur
e
Low he
ad pr
essur
e
N
o
he
ad
p
ress
u
re
Hig
h
su
ctio
n pr
essu
re
Low su
ctio
n pr
essu
re
N
o
su
ctio
n pr
es
su
re
Un
it
op
er
ating
in
a
va
cu
um
Re
ce
ive
r sigh
t gla
s
s emp
ty
S
u
ct
ion
lin
e
fr
ost
ing
b
a
c
k
U
n
a
b
le
to
pu
m
p
do
wn
sy
ste
m
Un
able
to
p
u
ll
va
cuum
in
lo
w
side
U
n
able to
hold vacuum in low s
ide
N
o
is
y compressor
Un
it no
t
re
frig
er
ating
Un
it no
t
h
eating
or d
e
frosting
Symptom
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
• Loose compressor pulley
• 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