Thermo King SLXi Spectrum, Maintenance Manual

Page: 318 / 342

Refrigeration System Diagnosis 14-2
ALL MODELS EXCEPT TCI AND SPECTRUM
Un
it ope
rati
n
g
w
ith reduced
hea
tin
g capa
ci
ty/
D
F
Un
it Operatin
g
with
red
uced refrigeration
capacity
Rapid cyclin
g
betwe
e
n Co
ol and Hea
t
U
n
it
co
ols
in
Heat a
n
d Defros
t
cy
cle
Un
it heats
in Refrigeration
cycle
High head
pre
ssure
Low head
pressure
No h
ead
pressu
re
High su
ction
p
ressure
Low suc
tion
p
ressure
No suction pressure Un
it
ope
rati
n
g
i
n
v
a
cu
um
Re
ceiver sight
glass empty
Suction line
frosting back
Un
ab
le t
o
p
u
m
p
do
w
n
s
y
st
em
Un
ab
le t
o
p
u
ll vacuum in compressor
Un
ab
le t
o
h
o
ld vacuum in compressor
Noisy compressor Un
it not
refrigerating
Un
it
not
hea
tin
g o
r d
efros
ti
ng
SY
MPT
O
M
POSSIBLE CAUSE
• • • • 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 worn 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