141
Fault
Possible cause
Fault phenomenon
Elimination method
R
ef
rig
er
at
io
n
fu
nc
tio
n
of
ai
r-
co
nd
iti
on
in
g
sy
st
em
do
es
no
tw
or
k
Refrigerant leak in the system
No pressure indication
Identify other causes
Refill with refrigerant
Electrical
devices
(compressor/evaporating
fan/condensate fan) work properly
or not
Normal pressure indication
Replace defective devices
Compressor
does
not
work
Loose or broken
belt
Normal pressure indication
Replace the belt or adjust it
to a value within prescribed
limit
No
pull-in
of
clutch/
circuit
problem
Repair or replace defective
parts
Circuit fault
Loose
plug
connector
The controlled electrical device does not work
Blown fuse
The electric device does not work
Failure
of
temperature
controlled switch
Compressor does not work
Damaged
pressure switch
Compressor does not work
Damaged relay
The controlled electrical device does not work
Damaged
refrigeration
switch
Devices other than evaporating fan do not work
Damaged
air
volume switch
No electrical device works
Other
circuit
damage
The controlled electrical device does not work
Plugged expansion valve
Low pressure (negative pressure), frosted outlet
of expansion valve
Clean the air-conditioning
system and replace drying
bottle or expansion valve
Plugged drying bottle
Low pressure is on the low side and beyond the
normal range, or is negative pressure
Noticeable temperature difference between
pipes on both sides of drying bottle, frost
formation on drying bottle
In
ad
eq
ua
te
re
fri
ge
ra
tio
n
Damaged or not well connected
air outlet
Low air speed at air outlet
Repair the air outlet
Heater valve for heat exchanger is
not closed or leaks water
Heat means the valve is not closed
Close water valve or make
replacement
Inadequate refrigerant
Both high pressure and low pressure are on the
high side
Check leaking positions,
add the right amount of
refrigerant
Surplus refrigerant
Both high pressure and low pressure are on the
high side, and there is no air bubble in level
glass
Let out the right amount of
refrigerant
Non-condensable gas within the
system
Both high pressure and low pressure are on the
high side
Filth blockage of air inlet of
evaporator/filth blockage within
core body
Too much earth and thick dirt on surface/objects
clogging air inlet
Clear away the filth
Failure of condensate fan
Zero current or no fan operation with damaged
fan blades
Check the circuit and
motor, make repair or
replacement
Filth blockage on condenser
surface
Too much earth and thick filth on surface
Flush with water
Condenser inlet air temperature is
too high, or the dissipation of
discharged
hot
air
is
not
satisfactory
Air inlet is above 40
℃
/air inlet is clogged
Keep air inlet able to take
in enough air and natural
wind
Loose belt
Harsh noise
Adjust the belt
Clogged expansion valve
Low pressure indicates negative pressure/frost
forms on evaporator
Replace expansion valve,
vacuumize again and add
refrigerant
Damaged expansion valve
No temperature difference between inlet and
outlet of expansion valve
Replace expansion valve,
vacuumize again and add
refrigerant
Clogged drying bottle
Low pressure is on the low side and beyond the
normal range, or is negative pressure
Replace drying bottle,
vacuumize again and add
refrigerant
Noticeable temperature difference between
pipes on both sides of drying bottle
