TK 56433-5-MM-EN
97
Refrigeration Diagnosis
Rapid
cycling
between
cool
and
heat
Unit
cools
in
heat
and
defrost
cycle
Unit
heats
in
refrigeration
cycle
High
head
pressure
Low
head
pressure
High
suction
pressure
Low
suction
pressure
No
suction
pressure
Unit
operating
in
a
vacuum
Receiver
sight
glass
empty
Suction
line
frosting
back
Unable
to
pump
down
system
Unable
to
pull
vacuum
in
low
side
Unable
to
hold
vacuum
in
low
side
Noisy
compressor
Unit
not
refrigerating
Unit
not
heating
or
defrosting
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
•
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
