Haima M3. A/C, Restraint System, Body Accessories, Electrical System. Instruction - part 1

 

Table of Contents

 

 

 

 

Volume III  A/C, Restraint System, Body 

Accessories and Electrical System 

 

Chapter 16   A/C System ························································································· 3A-1 

Chapter 17   Airbags and Restraint System···································································· 3B-1 

Chapter 18   Body and Accessories············································································· 3C-1 

Chapter 19   Electrical System ·················································································· 3D-1 

 

 

A/C System3A-1

 

 

 

Chapter 16 

A/C System 

Table of Contents 

Fault Diagnosis ·································································································· 3A-2 

Introduction ································································································ 3A-2 

Fault Diagnosis Index ···················································································· 3A-2 

Fault Symptom Diagnosis················································································ 3A-3 

Maintenance Warning and Instruction········································································ 3A-17 

Treatment of the refrigerant·············································································· 3A-17 

Storage of the refrigerant················································································· 3A-17 

Treatment of the compressor oil ········································································ 3A-17 

Maintenance Procedures for Refrigeration System························································· 3A-17 

Installing the manifold gauge············································································ 3A-17 

Recovering the refrigerant ··············································································· 3A-18 

Refrigerant filling ························································································· 3A-18 

Adding the refrigerant ···················································································· 3A-20 

Recovering the used R134a refrigerant ································································ 3A-20 

Adding fresh R134a refrigerant ········································································· 3A-20 

Checking the refrigerant·················································································· 3A-21 

Refrigeration System Performance Test································································ 3A-22 

Basic System····································································································· 3A-23 

Structure View ····························································································· 3A-23 

Removal/Installation of HVAC Assembly ····························································· 3A-23 

Disassembly/Assembly of HVAC······································································· 3A-23 

Removal/Installation of Air Flow Mode Main Linkage ············································· 3A-24 

Installation Instruction for Air Flow Mode Main Linkage ·········································· 3A-24 

Removal/Installation of A/C Compressor······························································ 3A-24 

Removal/Installation of Condenser ····································································· 3A-25 

Checking the Condenser ················································································· 3A-25 

Removal/Installation of Refrigeration Pipeline ······················································· 3A-25 

Removal/Installation of Blower Motor································································· 3A-25 

Removal/Installation of Resistor ········································································ 3A-26 

Removal/Installation of Ambient Temperature Sensor ·············································· 3A-26 

Checking the Ambient Temperature Sensor ··························································· 3A-26 

Removal/Installation of Interior Temperature Sensor················································ 3A-26 

Removal/Installation of A/C Controller································································ 3A-27 

 

 

 

A/C System3A-2

 

 

 

Fault Diagnosis 

Introduction 

  Refer to the Section Gl, read and comprehend 

the basic flow of fault diagnosis and conduct 
each step correctly.  

  When performing the fault diagnosis marked 

with (★), please shake the harness and the 
connector to check the connector pin for poor 
contact that causes the intermittent failure.  

 

 

If it is poorly contacted, please check to 
confirm each connector, wire and wiring 
harness are correctly connected without any 
damage.  

  The inspection (steps) parts are illustrated 

according to different line faults. Determine 
the fault symptom based on the following 
table and then troubleshoot the corresponding 
parts. 

 

Fault Diagnosis Index 

SN.

 

Fault Symptom

 

1

 

Insufficient or no air intake based on the air flow mode 

 

2

 

No air intake in each different air flow mode 

No change of the air inflow after the fan speed is changed

 

3

 

No change of the air flow mode

 

4

 

Abnormal/no air circulation

 

5

 

No operation at any temperature setting

 

6

 

Poor refrigeration effect of the A/C

 

7

 

No cool air out

 

8

 

There is noise under A/C operation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A/C System3A-3

 

 

 

Fault Symptom Diagnosis 

 

1

 

Insufficient or no air intake based on the air flow mode

 

Fault Diagnosis Hint: 

①

  VENT mode system fault:  

 Step 1-4 

②

  HEAT mode system fault:  

 Step 5 

③

  DEFROSTER mode system fault: 

 Step 6-8

 

Step

 

Inspection

 

Operation

 

Yes

 

Go to the next step.

 

1

 

Is there any normal 
resistance can be felt when 
operating the air flow mode 
control knob? 
Is it able to be operated to 
each position?

 

No

 

Conduct the steps listed under the No.3 Fault Diagnosis 
Index.

  

Yes

 

Go to the step 5.

  

2

 

Can the air be vented under 
the VENT mode?

 

No

 

Go to the next step.

 

Yes

 

Remove the obstruction and go to the step 9.

 

3

 

Is the air vent blocked?

 

No

 

Go to the next step.

 

Yes

 

Check the pipeline for any blockage, distortion or leakage 
and then go to the step 9.

 

4

 

Is the vent pipeline on the 
instrument panel is properly 
installed? 

 

No

 

Install the pipeline securely in place and then go to the step 
9.

 

Yes

 

Go to the next step.

 

5

 

Can the air be vented under 
the HEAT mode?

 

No

 

Check the air vent for any blockage and then go to the step 
9.

 

Yes

 

It operates normally, so recheck the fault symptom.

 

6

 

Can the air be vented under 
the DEFROSTER mode?

 

No

 

Go to the next step.

 

Yes

 

Remove the obstruction and then go to the step 9.

 

7

 

Is the air vent blocked?

 

No

 

Go to the next step.

 

Yes

 

Check the pipeline for any blockage, distortion or leakage 
and then go to the next step.

 

8

 

Is the defroster pipeline is 
properly installed?

 

No

 

Install the pipeline securely in place and then go to the next 
step.

 

Yes

 

End the fault diagnosis and explain the repair details to the 
customer. 

 

9

 

Can the air be vented?

 

No

 

If the fault reoccurs, recheck the fault symptom and start 
from the step 1.

 

 

 

 

A/C System3A-4

 

 

 

2 

No air intake in each different air flow mode 
No change of the air inflow after the fan speed is changed 

 
Fault Diagnosis Hint: 
①

 

Fault of the blower relay, the blower motor, the resistance or the fan switch 

 Step 

1 

②

 

Fault of the blower unit 

 Step 

2-4 

 

Step Inspection 

Operation 

Yes 

Go to the next step. 

1 

Check the following systems and 
electrical parts: 
blower relay, blower motor, resistance, 
electronic fan switch. 
Are they normal?  

No 

Repair or replace the faulty parts and then go 
to the step 5.  

Yes 

Go to the step 4. 

2 

Turn the ignition switch to ON position 
Turn on the fan switch to enable the 
interior air circulation 
Is the fan of the blower unit rotating 
smoothly? 

No 

Go to the next step. 

Yes 

Go to the next step. 

3 

Check whether the fan of the blower unit 
is normal? 
Is the fan interfering with the fan frame? 
Are there any foreign matters or obstacles 
in the fan? 

No 

Remove the foreign matters, repair or replace 
the fan and the fan frame, and then go to the 
step 5. 

Yes 

Remove the obstacles and go to the next step.

4 

Is the air inlet/vent of the blower unit 
blocked?  

No 

Check the passage between the blower unit 
and the heater unit for any blockage and then 
go to the next step. 

Yes 

End the fault diagnosis and explain the repair 
details to the customer.  

5 

Can the air be vented? 

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

 

 

 

 

 

 
 

 

A/C System3A-5

 

 

 

 

3 

No change of the air flow mode 

 
Fault Diagnosis Hint: 
1) 

Fault of the air flow mode linkage, crank, rod, cable and cable clip. 

 

Step 1, 2 

2) 

Fault of the climate control unit gear rack and the air flow mode cable. 

 Step 

3 

3) 

Fault of one or more heater unit openings. 

 Step 

4,5 

 

Step Inspection 

Operation 

Yes 

Go to the next step. 

1 

Check the air flow mode linkage, crank, rod 
and cable clip.  
Are the linkage and the crank lubricated?  
Are all the linkage, crank and rod installed in 
place?  
Is the cable clip distorted?  
Are the above items normal? 

No 

Apply the grease or install the linkage, 
crank and rod securely in place; repair 
or replace the cable clip and then go to 
the step 6. 

Yes 

Go to the next step. 

2 

Is the air flow mode cable securely fixed? 
Does it match correctly with the air flow mode 
linkage of the heater unit? 

No 

Adjust the air flow model cable or 
install it correctly, and then go to the 
step .6. 

Yes 

Remove the obstruction and then go to 
the step 9. 

3 

Check the climate control unit. 
Is the gear rack engaged normally?  
Is the air flow mode cable correctly installed 
on the gear rack?  
Are the above items normal? 

No 

Go to the next step. 

Yes 

Remove the obstacles and then go to 
the step 6. 

4 

Are there any obstacles at each opening of the 
heater unit?  

No 

Go to the next step. 

Yes 

Check each opening for any crack or 
damage and then go to the next step. 

5 

Are all the openings of the heater unit correctly
and securely installed? 

No 

Install the openings securely in place 
and then go to the next step. 

Yes 

End the fault diagnosis and explain the 
repair details to the customer. 

6 

Does the air flow mode change?  

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

 

 

 

A/C System3A-6

 

 

 

 

4 Abnormal/no 

air 

circulation 

 
Fault Diagnosis Hint: 
①

 

Fault of the blower unit intake linkage, crank, cable and cable clip 

 Step 

1、2 

②

 

Fault of the intake cable of the climate control unit  

 Step 

3 

③

 

Fault of the blower unit air inlet 

 Step 

4、5 

 

Step Inspection 

Operation 

Yes 

Go to the next step. 

1 

Check the blower unit intake linkage, intake 
crank and cable clip. 
Are the linkage and the crank lubricated? 
Are the linkage and the crank correctly and 
securely installed? 
Is the cable clip distorted?  
Are the above items normal? 

No 

Apply the grease or install the linkage 
and crank correctly and securely in place, 
or replace the cable clip, and then go to 
the step 6. 

Yes 

Go to the next step. 

2 

Is the intake cable correctly and securely 
installed in the position corresponding to the 
intake linkage of the blower unit?  

No 

Adjust the intake cable or install it 
correctly, and then go to the step .6. 

Yes 

Go to the next step. 

3 

Is the intake cable correctly and securely 
installed in the position corresponding to the 
railing of the climate control unit? 

No 

Install the intake cable correctly and 
securely, and then go to the step 6. 

Yes 

Remove the obstacles, and then go to the 
step 6. 

4 

Are there any obstacles at the air inlet of the 
blower unit? 

No 

Go to the next step. 

Yes 

Check the air inlet for any crack or 
damage and then go to the next step. 

5 

Is the air inlet of the blower unit correctly and
securely installed? 

No 

Install the air inlet securely in place and 
then go to the next step. 

Yes 

End the fault diagnosis and explain the 
repair details to the customer. 

6 

Is there any air circulation? 

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

 

 

 

A/C System3A-7

 

 

 

 

5 

No operation at any temperature setting 

Fault Diagnosis Hint: 
④

 

Fault of the air mixing linkage, crank, pull rod, cable and cable clip of the heater unit  

 Step 

2、3 

⑤

 

Fault of the gear rack and air mixing cable of the climate control unit  

 Step 

4 

⑥

 

Fault of the air mixing port of the heater unit 

 Step 

5、6 

 

Step Inspection 

Operation 

Yes

Go to the next step. 

1 

Is the coolant preheated?  

No 

Preheat the engine and then go to the 
step 7. 

Yes

Go to the next step. 

2 

Check the air mixing linkage, crank, pull 
rod and cable clip of the heater unit.  
Are the linkage and the crank lubricated?  
Are the linkage, crank and pull rod securely 
installed in place?  
Is the cable clip distorted? 
Are the above items normal? 

No 

Apply the grease or install the linkage, 
crank and pull rod correctly and 
securely in place, or replace the cable 
clip, and then go to the step 6. 

Yes

Go to the next step. 

3 

Is the air mixing cable correctly installed on 
the position corresponding to the air mixing 
linkage of the heater unit?  

No 

Adjust the air mixing cable or install it 
securely in place, and then go to the 
step 7. 

Yes

Go to the next step. 

4 

Check the climate control unit. 
Is the gear rack correctly engaged?  
Is the air mixing cable securely installed on 
the right position of the frame? 
Are the above items normal? 

No 

Make the gear rack correctly engaged, 
or install the air mixing cable correctly 
in place and then go to the step 7. 

Yes

Remove the obstacles, and then go to 
the step 7. 

5 

Are there any obstacles at the air mixing 
port of the heater unit? 

No 

Go to the next step. 

Yes

Check the air mixing port for any crack 
or damage and then go to the next step.

6 

Is the air mixing port of the heater unit 
correctly and securely installed? 

No 

Install the air mixing port correctly and 
securely in place and then go to the 
next step. 

Yes

End the fault diagnosis and explain the 
repair details to the customer. 

7 

Does it operate normally at each 
temperature setting?  

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

A/C System3A-8

 

 

 

 

6 

Poor refrigeration effect of the A/C 

Fault Diagnosis Hint: 
1. 

Fault of the drive belt  

 Step 

2 

2. 

Fault of the blower unit or condenser  

 Step 

4-5 

3. 

Fault of the receiver/dryer or expansion valve  

 Step 

8-9 

4. 

Fault of the refrigeration pipeline  

 Step 

10-11 

5. 

Fault of the A/C compressor system or insufficient compressor oil  

 Step 

15,-16 

6. 

Too much compressor oil or the fault of expansion valve or heater unit linkage or air mixing 

linkage  
 Step 

17-19 

Step Inspection 

Operation 

Yes 

It operates normally (recheck the fault 
symptom) 

1 

Perform the refrigeration system 
performance test. 
Refer to the maintenance procedures of the 
refrigeration system to perform the 
performance test. 
Does it operate normally?  

No 

Go to the next step. 

Yes 

Go to the next step. 

2 

Is the drive belt normal? 
Refer to Checking the Drive Belt, Drive 
Belt, Section B.  

No 

Adjust or replace the drive belt and 
then go to the step 20. 
Refer to Adjusting the Drive Belt, 
Drive Belt, Section B. 

Yes 

Go to the next step. 

3 

Check the refrigerant pressure at the 
high/low pressure end. Is the pressure 
within the limit? 

No 

Go to the step 6. 

Yes 

Remove the obstruction and then go to 
the step 20. 
(In the evaporator unit, if the air does 
not arrive at the evaporator, the heat 
exchange cannot generate and the 
refrigerant pressure shall rise; 
therefore, the obstruction should be 
removed timely) 

4 

Is the blower air inlet blocked? 

No 

Go to the next step. 

Yes 

Adjust the refrigerant to the specified 
volume and then go to the step 20. 
(excessive refrigerant) 

5 

Does the condenser operate normally?  
Refer to Checking the Condenser, Basic 
System.  

No 

Replace the condenser or repair and 
clean the condenser cooling fin, and 
then go to the step 20. 

Yes 

Go to the next step. 

6 

Is the refrigerant pressure both at the high 
end and low end below the standard?  

No 

Go to the step 14. 

Yes 

Go to the next step.  

7 

When the A/C compressor is turned on, 
can the pressure at the high end increase 
immediately to the specified value and 
then decrease and become stable? (Is there 

No 

Go to the step 10. 

 

A/C System3A-9

 

 

 

any negative pressure at the low pressure 
end?) 

Yes 

Go to the next step. 

8 

Turn off the A/C switch to stop the A/C for 
10min. 
Start the engine. 
Turn on both the A/C switch and the fan 
switch. 
Is there still fault when the A/C 
compressor is turned on?  

No 

Replace the receiver/dryer and then go 
to the step 20. 
(It is necessary to replace it because 
there is water mixed into the 
receiver/dryer.) 

Yes 

Replace the expansion valve and then 
go to the step 20. (The replacement is 
necessary, because the valve is closed 
too much) 

9 

Is thermal sensing tube of the expansion 
valve in the evaporator unit installed 
correctly and securely? 

No 

Install thermal sensing tube of the 
expansion valve in the evaporator unit 
correctly and securely and then go to 
the step 20.  

Yes 

Go to the next step. 

10 

Check the refrigeration pipeline. 
Is the conduit damaged or fissured? 
Is there any greasy dirt on the conduit 
connector? (By visual inspection) 
Is there any leakage on the conduit 
connector?  
Is there any leakage at the connection pipe 
of the condenser? 
Is there any leakage at the connection pipe 
of the receiver/dryer? 
Is there any leakage at the connection pipe 
of the A/C compressor? 
Is there any leakage at the connection pipe 
of the evaporator unit?  
Perform the air leak detection by using the 
air leak detector.  
Are the above items normal? 

No 

If the conduit or A/C parts are 
damaged or fissured, replace them and 
then go to the step 20; if not, go to the 
step 13. 

Yes 

Adjust the compressor oil and the 
refrigerant to the specified volume and 
then go to the step 20. 

11 

Is there any leakage at the connections of 
the pipeline of the evaporator unit?  

No 

If the pipeline is damaged or fissured, 
replace it, and then go to the step 20; if 
not, go to the next step. 

Yes 

Tighten the connector to the specified 
torque, adjust the compressor oil and 
the refrigerant to the specified volume 
and then go to the step 20. 

12 

Does the pipeline connector of the 
evaporator core in the evaporator unit 
become loose? 

No 

Replace the O-ring on the conduit, 
adjust the compressor oil and the 
refrigerant to the specified volume and 
then go to the step 20. 

Yes 

Tighten the connector to the specified 
torque, adjust the compressor oil and 
the refrigerant to the specified volume 
and then go to the step 20. 

13 

Does the conduit connector become loose? 

No 

Replace the O-ring on the conduit, 
adjust the compressor oil and the 
refrigerant to the specified volume and 
then go to the step 20. 

 

A/C System3A-10

 

 

 

Yes 

Go to the next step (if nearly no 
increase of pressure) 

14 

Is there nearly no increase of pressure at 
the high pressure end of the A/C 
refrigeration system?  

No 

Go to the step 17  

Yes 

Go back to the step 3. 

15 

Is there any increase of pressure at the high 
pressure end under the high speed 
operation of the engine? 

No 

Go to the next step. 

Yes 

End the fault diagnosis and explain to 
the customer that the fault is caused by 
insufficient compressor oil. 

16 

Is there any increase of pressure at the high 
pressure end when the compressor oil is 
added to the specified volume? 

No 

Replace the A/C compressor and then 
go to the step 20 (A/C compressor 
fault) 

Yes 

Go to the step 19. 

17 

Is the refrigerant pressure relatively high 
only at the low pressure end?  

No 

Go to the next step. 

Yes 

Adjust the compressor oil to the 
specified volume and then go to the 
step 20. (A/C compressor oil volume 
exceeds the specified) 

18 

Are the air mixing linkage, crank and pull 
rod of the heater control unit installed 
correctly? 

No 

Repair or install the linkage, crank and 
pull rod and then go to the step 20. 

Yes 

Repair the expansion valve and then go 
to the next step. (The replacement is 
necessary, because the expansion valve 
is opened too much) 

19 

Is thermal sensing tube of the expansion 
valve in the evaporator unit installed 
correctly and securely?  

No 

Install thermal sensing tube securely 
and then go to the next step. 

Yes 

End the fault diagnosis and explain the 
repair details to the customer. 

20 

Can the cool air be vented?  
(Is the result of the refrigeration system 
performance test normal?) 

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

A/C System3A-11

 

 

 

 

7 

No cool air out 

Fault Diagnosis Hint: 
①

 

Fault of the A/C switch indicator lamp Step 3-5 

②

 

Fault of PCM A/C turn-off control system and the cooling system 

 

Step 6, 22 

③

 

Fault of the A/C amplifier, A/C switch, potentiometer 

 Step 

8-14 

④

 

PCM(A/C signal) system fault  

 Step 

15,16 

⑤

 

Fault of the refrigerant pressure switch and the cooling system 

 Step 

17-19 

⑥

 

PCM (IG1 signal) system fault  

 Step 

20,21 

⑦

 

Compressor system fault 

 Step 

23,24 

⑧

 

A/C relay system fault 

 Step 

25-27 

 
Step Inspection 

Operation 

Yes

Go to the next step. 

1 

Can the cool air vented?  

No 

Conduct the step 1 listed in the Fault 
Diagnosis Index 1 and 2. 

Yes

Conduct the step 1 listed in the Fault 
Diagnosis Index 6. 

2 

Start the engine.  
Turn on both the A/C switch and the fan 
switch simultaneously. 
Does the A/C compressor operate normally?

No 

Go to the next step. 

Yes

Go to the step 6. 

3 

Does the A/C switch indicator lamp come 
on? 

No 

Go to the next step. 

Yes

Go to the next step. 

*4 

Turn the ignition switch to the ON position. 
Test the voltage (IG2) signal of the Pin C of 
the A/C switch.  
Is the voltage about 12V? 

No 

Repair the harness between the fuse 
box and the A/C switch and then go to 
the step 28. 

Yes

Check the A/C switch and then go to 
the step 28. 

*5 

Turn on both the A/C switch and the fan 
switch simultaneously. 
Test the voltage (A/C signal) of the Pin A of 
the A/C switch. 
Is the voltage about 12V? 

No 

Repair the harness between the A/C 
switch box and the fan switch and then 
go to the step 28. 

Yes

Conduct the corresponding inspection. 

6 

Check the DTC of the PCM on-board 
diagnostic system. Is the DTC displayed as 
follows: 
(ZM, FP and ZL) DTOs 
0117,0118,0122,0123,0335 
Refer to the Checking the DTC, Fault 
Diagnosis System, Section F. 

No 

Go to the next step. 

Yes

Go to the step 15 

*7 

Turn the ignition switch to the LOCK 
position. 
Disconnect the refrigerant pressure switch.  
Turn the ignition switch to the ON position.
Set the fan speed at the position 1. 
Test the refrigerant pressure switch 

No 

Connect the refrigerant pressure switch 
connector and then go to the next step. 

 

A/C System3A-12

 

 

 

connector (at the wiring harness side) 
The voltage of the following pin: 
·Pin A (A/C signal) 
Is the voltage about 12V when the A/C 
switch is turned off? Is the voltage is 0V 
when the A/C switch is turned on? 

Yes

Stop the short circuit and then go the 
next step. 

*8 

Turn the ignition switch to the LOCK 
position. 
Disconnect the A/C amplifier connector.  
Start the engine 
Turn on both the A/C switch and the fan 
switch simultaneously. 
Is there any cool air vented out when the Pin 
B and C of the A/C amplifier connector is 
short circuited? 

No 

Stop the short circuit and then go to the 
step 13. 

Yes

Go to the next step. 

*9 

Turn the ignition switch to the ON position.
Test if the voltage of the Pin C (IG2 signal) 
of the A/C amplifier connector is about 
12V. 

No 

Repair the harness between the fuse 
box and the A/C amplifier and then go 
to the step 28. 

Yes

Repair the harness between the 
refrigerant pressure switch box and the 
A/C amplifier and then go to the step 
28. 

*10 

Test if the voltage of the Pin B (A/C signal) 
of the A/C amplifier connector is about 
12V. 

No 

Go to the next step.  

Yes

Go to the next step. 

11 

Is the potentiometer normal? 
Refer to Checking the Potentiometer, 
Control System. 

No 

Replace the potentiometer and then go 
to the step 28. 

Yes

Repair the harness between the A/C 
amplifier and the potentiometer and 
then go to the step 28. 

12 

Is the amplifier normal? 
Refer to Checking the A/C Amplifier, 
Control System. 

No 

Replace the A/C amplifier and then go 
to the step 28. 

Yes

Go to the next step. 

*13 

Turn the ignition switch to the LOCK 
position. 
Check the continuity between the Pin B 
(A/C signal) of the A/C amplifier connector 
and the following refrigerant pressure 
switch connector pin (A/C signal). 
Are they in continuity? 

No 

Repair the wiring harness between the 
refrigerant pressure switch box and the 
A/C amplifier and then go to the step 
28. 

Yes

Check the wiring harness between the 
A/C amplifier and the A/C breaker and 
then go to the step 28. 

*14 

Turn the ignition switch to the ON position.
Turn on the A/C switch。 
Turn off the fan switch. 
Is the Pin B (A/C signal) of the A/C switch 
connector about 12V?  

No 

Check the A/C switch and then go to 
the step 28. 

Yes

Go to the step 17 

*15 

Is the voltage of the Pin B (A/C signal) of 
the refrigerant pressure switch connector 
about 12V? 

No 

Go to the next step. 

Yes

Repair the wiring harness between the 
PCM and the refrigerant pressure 
switch and then go to the step 28. 

*16 

Is the voltage of the Pin 1P (A/C signal) of 
the PCM connector (22-core) about 12V? 

No 

Check the PCM and then go to the step 
28. 

17 

Is there any cool air out when the following 

Yes

Go to the next step. 

 

A/C System3A-13

 

 

 

pins of the refrigerant pressure switch 
connector are short circuited?  
Pins A-B (A/C signal) 

No 

Stop the short circuit and reconnect the 
refrigerant pressure switch connector, 
and then go to the step 20. 

Yes

Stop the short circuit and reconnect the 
refrigerant pressure switch connector, 
and then go to the step 20. 

18 

Is the refrigerant pressure normal?  
Refer to Checking the Refrigerant Filling, 
Refrigeration System Maintenance 
Procedure. 

No 

Go to the next step. 

Yes

Check the refrigerant pressure switch 
and then go to the step 28. 

19 

Is the refrigerant metering normal? 
Refer to Checking the Refrigerant Filling, 
Refrigeration System Maintenance 
Procedure. 

No 

Adjust the refrigerant to the specified 
value and then go to the step 28. 

Yes

Stop the short circuit and then go the 
next step.  

*20 

Does the electromagnetic clutch operate 
when the Pin B (IG1 signal) of the A/C 
relay connector is grounded?  

No 

Go to the step 22 

Yes

Go to the next step. 

*21 

Turn off the A/C switch. 
Is the voltage of the Pin 1S (IG1) of the 
PCM connector (22-core) about 12V? 

No 

Repair the wiring harness between A/C 
relay and the PCM and then go to the 
step 28. 

Yes

Check the operation of the refrigerant 
system. Refer to Checking the Control 
of the CONDENSER fan, Cooling Fan 
Control, System Inspection, Section F. 

*22 

Check the following input signal 
components: 
engine coolant temperature sensor, 
transmission gear switch, neutral switch, 
power steering switch, crank angle position 
sensor, accelerator pedal position sensor and 
PCM wiring harness (A/C – cutoff control) 
Are they normal? 

No 

Replace the input signal components 
and then go to the step 28. 

Yes

Go to the next step. 

*23 

Is the voltage of the Pin A (A/C control 
signal) of the electromagnetic clutch 
thermal protector about 12V? 

No 

Go to the step 25 

Yes

Replace thermal protector and then go 
to the step 28. 

*24 

Is the electromagnetic clutch normal? 
Refer to Checking the Electromagnetic 
Clutch, Control System. 

No 

Replace the electromagnetic clutch coil 
and then go to the step 28. 

Yes

Go to the next step. 

*25 

Is the A/C relay power fuse normal? 

No 

Check whether the circuit with a blown 
fuse is short circuited to the ground. 
Repair or replace accordingly. Install a 
fuse of the appropriate rating. 

Yes

Go to the next step. 

*26 

Turn the ignition switch to the ON position.
Is the voltage of the following pins of the 
A/C relay unit about 12V? 
Pin A (IG1 signal) 
Pin C (A/C control signal) 

No 

Repair the harness between the A/C 
relay and the fuse box and then go to 
the step 28. 

Yes

Repair the harness between the A/C 
relay and thermal protector and then go 
to the next step. 

*27 

Is the voltage of the Pin D (A/C control 
signal) of the A/C relay unit about 12V?  

No 

Check the A/C relay and then go to the 
next step. 

Yes

End the fault diagnosis and explain the 
repair details to the customer. 

*28 

Is there any cool air out? (Is the result of the 
refrigeration system performance test 
normal?) 

No 

If the fault reoccurs, recheck the fault 
symptom and start from the step 1. 

 

 

A/C System3A-14

 

 

 

 

 

8 

There is noise under A/C operation. 

Fault Diagnosis Hint: 
1. 

Operating noise of the electromagnetic clutch  

 Step 

4 

2. 

Noise from the A/C compressor blades  

 Step 

5-13 

3. 

Noise from the A/C compressor slipping  

 Step 

14-17 

4. 

Interference noise of the hose or refrigeration pipeline 

 Step 

18 

Step Inspection 

Operation 

Yes Go to the step 5 

1 

Is there any tinkle, crackle, beep and 
buzzer? (Is the noise from the A/C 
compressor blades?) 

No

Go to the next step. 

Yes Go to the step 14 

2 

Is there any grating and whir? (Is the noise 
from the A/C compressor slipping)? 

No

Go to the next step. 

Yes Go to the step 18 

3 

Is there any clash and chatter (babble)? 

No

Go to the next step. 

Yes

Adjust the clearance between the 
electromagnetic clutch pressure plate and the 
compressor belt pulley and then go to the 
step 19. 
Refer to Adjusting the Electromagnetic 
Clutch, Control System. 

4 

Is there any click sound? (the operating 
noise of the electromagnetic clutch) 

No

The condition is normal (recheck the fault 
symptom) 

Yes Go to the next step. 

5 

Does the noise last for more than 3s after 
the A/C compressor is turned on?  

No

The condition is normal (the noise only 
occurs in 2~3s after the A/C compressor is 
turned on) 

Yes Go to the next step. 

6 

Is the idle speed normal? 
·Refer to the Idle Speed Adjustment, Engine
Adjustment, Section F. 

No

Adjust the idle speed and then go to the step 
19. 

Yes Go to the step 10 

7 

Is the refrigerant volume normal? 
·Refer to Checking the Refrigerant Filling, 
Refrigeration System Maintenance 
Procedure.  

No

Go to the next step. 

Yes Go to the next step. 

8 

Check the refrigerant pipeline. 
Is there any damage and crack of the 
pipeline? 
Is there any greasy dirt at the pipeline 
connection? (By visual inspection) 
Is there any leakage at the pipeline 
connection?  
Is there any leakage at the connection pipe 
of the condenser? 
Is there any leakage at the connection pipe 
of the receiver/dryer? 
Is there any leakage at the connection pipe 

No

If the pipeline or A/C parts are damaged or 
fissured, replace them, and then go to the 
step 19. If there is air leakage, repair or 
replace the connector, replace the 
receiver/dryer and then go to the step 19. 

 

A/C System3A-15

 

 

 

of the A/C compressor? 
Is there any leakage at the connection pipe 
of the evaporator unit? 
Perform the air leak detection by using the 
air leak detector. 
Are the above items normal? 

Yes

Adjust the refrigerant to the specified 
volume and then go to the step 19. 

9 

Is there any leakage at the connections of 
the pipeline of the evaporator unit? 

No

If the pipeline or A/C parts are damaged or 
fissured, replace them, and then go to the 
step 19. If there is air leakage, repair or 
replace the connector, replace the 
receiver/dryer and then go to the step 19. 

Yes Go to the next step. 

10 

Add the 20ml{20cc.0.8fl oz} compressor 
oil. 
Can any noise be heard under the high 
operation of the engine?  

No

End the fault diagnosis and explain the 
repair details to the customer. 

Yes Go to the next step. 

11 

Drain the compressor oil. 
Is there any metallic particulate pollutant?

No

Replace the A/C compressor and then go to 
the step 19. 

Yes

Replace the entire A/C system (except for 
the heater) and then go to the step 19. 

12 

Is the compressor oil whitened or be mixed 
with water? 

No

Go to the next step. 

Yes

Replace the A/C compressor and the 
receiver/dryer (because the A/C compressor 
may be worn and the receiver/dryer may be 
blocked, it is necessary to replace them) and 
then go to the step 19. 

13 

Is there any click sound? (the operating 
noise of the electromagnetic clutch) 

No

The condition is normal and recheck the 
fault symptom. 

Yes

Replace the A/C compressor, and then go to 
the step 19.(A/C compressor drain valve is 
kept open) 

.14 

Can you hear any noise right after the A/C 
compressor stops?  

No

Go to the next step. 

Yes Go to the next step. 

15 

Is the drive belt normal? 
Refer to Checking the Drive Belt, Drive 
Belt, Section B. 

No

Adjust or replace the drive belt and then go 
to the step 19. 

Yes

Remove the sundries and greasy dirt or 
replace the drive belt, and then go to the step 
19. 

16 

Is the drive belt worn? Is there any attached 
sundries? Is there any greasy dirt? 

No

Go to the next step. 

Yes

Replace the A/C compressor (except for the 
electromagnetic clutch pressure plate, the 
belt pulley and the coil) and then go to the 
step 19. 

17 

Is the electromagnetic clutch normal? 
Refer to Checking the Electromagnetic 
Clutch, Control System. 

No

Replace the electromagnetic clutch and then 
go to the step 19. 

Yes

Visually check the A/C compressor and 
replace relevant parts when necessary, and 
then go to the next step. 

18 

Is the noise from the A/C compressor? 

No

If the noise is caused by the refrigerant 
pipeline, repair the loosened or missed clips 
and tighten the screws, and then go the next