365 

 
No. 267 Air conditioning has abnormal sound   

Malfunction 

t

Cause Solution 

(1)The driving belt has not been tensioned. It will be prolonged in the process of usage and 
thus cause the abnormal sound; the belt shall be re-tensioned in case of this situation 
occurs;  

(2).The pulley and the tensioner bearing break down with rumbling sound during the 
operation; a harsh feeling is showed when rotating the pulley by hand: replace the bearing, 
check the tensioner and the pulley, replace them in case they are out of service.   

(3)The abnormal sound may be caused by the looseness of the mounting bolt between the 
engine and the compressor bracket as well as untightening of the bolt when mounting the 
compressor bracket; the bolt shall be checked and retightened to ensure its reliable 
connection;  

(4).The compressor is oil shortage that causes the piston seizure, the piston scraping and 
also the abnormal sound: the refrigeration oil shall be added;   

(5).Too much or too little refrigerant, which causes the malfunction or the liquid impact of the 
compressor; the refrigerant must be refilled;   

(6).Failure of compressor electromagnetic clutch; replace the electromagnetic clutch or the 
compressor assembly;   

(7).Undersupply of the sedan generator battery that causes the insufficiency in the 
compressor electromagnetic clutch coil suction resultant; the electromagnetic clutch is in 
nearly sucking condition, which may cause the abnormal sound; the generator battery shall 
be checked or replaced;   

The compressor 
has abnormal 
sound 

(8).The pulley is un-tightened: tightening the fastening screw;   

(1).The abnormal sound is generated owing to the mismatch of the thermo expansion valve 
structure with the system; it normally occurred when opening or closing the air conditioning; 
here opening of the thermo expansion valve can be lowered (clockwise fasten the set screw 
by half turn to 3/4 turn; over low fastening has no effect and over high fastening will influence 
the performance); replace the thermo expansion valve if the above method is invalid;   

(2)Performance of the thermo expansion valve does not mate with the system. The thermo 
expansion valve will have an abnormal sound under certain operation mode if the capacity of 
the thermo expansion valve is too large; replace into a thermo expansion valve of suitable 
capacity.  

(3).Resonance of the thermo expansion valve will be caused if the thermo expansion valve 
structure does not mate with the system; the thermo expansion valve shall be replaced under 
this condition;   

The thermo 
expansion valve 
has abnormal 
sound 

(4). It is caused by the quality problem of the thermo expansion valve such as ultra low of the 
spring force; the thermo expansion valve shall be replaced;   

(1) abnormal sound of the blower, imbalance of the blower fan blade, abnormal sound 
caused by excessive wear of the blower motor: replace the blower;   

(2) Looseness of the clamp or the knock during the operation: tighten the clamping stirrup, 
eliminate the friction or the vibration between the hoses and other parts;   

(3) There has chatter in the pressure line caused by overfilling of the refrigerant; surplus 
refrigerant shall be discharged;   

 
The 
compressor 
has abnormal 
sound during 
the operation 

The air 
conditioning has 
other abnormal 
sound 

(4) There has hissing sound at inlet of the thermo expansion valve caused by inadequate 
filling of the refrigerant; the refrigerant shall be supplied;   

 
 

 

 

366 

Abnormal noise of the auto air conditioning reversing servomotor of generation II Vision and 
Leading; replace the servomotor 

 

 

 

No. 268 The air conditioning has no heating supply or the heating air is not warm   

Malfunction 

t

Cause Solution 

Malfunction of the blower switch  1) Malfunction of the blower switch: replace the blower switch;   

2). Air leak of the heating radiator shell or the blower shell: tighten the connection 
screw and replace the sealing gasket;   

Air leak of the heating radiator 
shell or the blower shell 
The cooling fin of the hot-water 
pipe inside the heating radiator is 
squeezed and deformed. 

3). Cooling fin of the hot-water pipe inside the heating radiator is squeezed and 
deformed, which blocks the wind passing through the heater: straighten the 
cooling fin with a nipper pliers; it shall be replaced by a new heater in case that 
the cooling fin is unable to be straightened.   

Hot air outlet is blocked by the 
heating radiator felt gasket 

4). Hot air outlet is blocked by the heater felt gasket: readjust the felt gasket 
position;  

The water valve switch is in 
wrong open position 

Reopen it in correct position;   

The air 
conditioning 
has no 
heating 
supply or 
the heating 
air is not 
warm 

Improper adjustment to the mix 
air throttle 

5). Improper adjustment to the mix air throttle: re-adjust the air throttle;   

The air conditioning has abnormal sound 

Abnormal noise of the 
compressor 

Other abnormal sounds of the air 
conditioning 

Abnormal noise of the 

thermo 

expansion

 valve 

Overhaul or replace 

Overhaul or replace 

Replace 

Normal 

Abnormal 

Abnormal 

Abnormal 

Normal 

 
 

 

 

367 

 

The air conditioning has no heating supply or 
the heating air is not warm 

The blower switch is out of 
service 

The heating radiator shell or the 
blower shell is air leakage 

The cooling fin of the hot-water pipe 
inside the heating radiator is 
squeezed and deformed. 

Hot air outlet is blocked by the heating radiator felt 
gasket 

The mix air throttle is in improper 
adjustment 

Overhaul or replace 

Overhaul or replace 

Overhaul or replace 

Adjust 

Adjust 

Normal 

Normal 

Normal 

Normal 

Malfunction

Air leakage

Deformation

Block

Improper adjustment

 
 

 

 

368 

 

No. 269 A/C compressor fails to start   

Malfunction 

symptom 

Cause Solution 

Fuse, electric appliance 
element and relay are 
malfunction 

relative fuse is blown, the electric appliance element is of poor contact, the relay 
coil is broken: check the service condition of each electric appliance element and 
replace damaged one;   

The belt is over loose 

Readjust or replace the belt 

Failure of low voltage 
switch 

Low temperature protection switch takes effect; when the environment 
temperature is lower than 15oC, the low temperature protection switch will 
automatically cut out the circuit controlling the compressor: check if the 
environment temperature is lower than 15oC and if the low temperature protection 
switch is in normal operation;   

Water temperature is too 
high 

Check and eliminate the failure of ultra high in water temperature;   

The idle speed is too low  Eliminate it per the preclusion method of too low idle speed of engine;   

The temperature 
controller is failure 

Performance parameter of the temperature controller is over proofed while the 
temperature inside the car is ultra high, but the temperature controller is incapable 
of being switched on to operate the compressor: replace the temperature 
controller;  

The thermo sensitive 
resistance is damaged 

The thermo sensitive resistance is damaged and incapable of sensing the 
temperature correctly: check and replace the thermo sensitive resistance;   

High pressure switch 

The high pressure switch takes the protection effect so that the compressor fails to 
start; check if the high pressure is too high and the system is blocked;   

The electromagnetic 
clutch can not be sucked 
together 

The electromagnetic clutch can not be sucked together and is incapable of being 
operated along with the compressor: check if the clearance of the electromagnetic 
clutch is too large, replace the electromagnetic clutch;   

The electromagnetic 
clutch can’t work 

The electromagnetic clutch can’t work: check if the electromagnetic clutch coil is 
broken, replace the electromagnetic clutch;   

The refrigerant is leaking  The refrigerant is leaked to the set value of low pressure switch, the low pressure 

protection switch takes effect so that the compressor fails to start: check the 
system leaking position and eliminate it;   

The compressor bearing 
is damaged or oil 
shortage 

The compressor bearing is damaged or oil shortage: replace the compressor and 
fill up the refrigeration oil as required;   

Cylinder sticking of 
compressor  

Cylinder sticking of compressor; there may have foreign materials inside the 
cylinder or the piston position maybe changed after long-term abrasion that causes 
the seizure or the oil shortage: remove the compressor for replacement;   

A/c compressor 
assembly fails to 
start when the 
a/c is in 
operation 

Malfunction of ECU 
interior short circuit 
control 

Replace the ECU assembly