2005 MITSUBISHI LANCER Workshop Manual

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-13
STEP 5. Voltage measurement at the B-114 A/C
compressor connector.
(1) Disconnect the connector, and measure at the
wiring harness side.
(2) Turn the ignition switch to the "ON" position.(3) Disconnect engine-ECU connector C-123, and
earth terminal 8.
(4) Disconnect engine-A/T-ECU connector C-122,
and earth terminal 20.
(5) Measure the voltage between terminal 1 and
body earth.
OK: System voltage
Q: Is the check result normal?
YES :
Go to Step 6.
NO : Refer to Inspection procedure 11 "A/C
compressor power supply system P.55-59."
AC303782
Connector: B-114
<4G1-L.H.D.>
AC
Harness side
B-114 (B)
AC303790
Connector: B-114
<4G6-L.H.D.>
AC
Harness side
B-114 (B)
AC303805
Connectors: C-122 , C-123

C-122 (GR)
C-123 (Y)
C-122 Harness side
C-123
AE
AC305159 Connector C-123
(Harness side)AB
AC305161
Connector C-122
(Harness side)
AB
AC301541EW
Connector B-114
(Harness side)
1

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-14
STEP 6. Connector check: C-139 A/C-ECU
connector
Q: Is the check result normal?
YES :
Go to Step 7.
NO : Repair the connector.
STEP 7. Voltage measurement at C-139 A/C-ECU
connector.
(1) Disconnect the connector, and measure at the
wiring harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Turn the blower switch to the "ON" position.
(4) Measure the voltage between terminal 8 and
body earth.
OK: System voltage
Q: Is the check result normal?
YES :
Go to Step 10.
NO : Go to Step 8.
STEP 8. Connector check: C-109 resistor
connector
Q: Is the check result normal?
YES :
Go to Step 9.
NO : Repair the connector.
STEP 9. Check the wiring harness between C-109
resistor connector terminal No.4 and C-139
A/C-ECU connector terminal No.8.
Q: Is the check result normal?
YES :
The trouble can be an intermittent
malfunction (Refer to GROUP 00, How to
Cope with Intermittent Malfunction P.00-5).
NO : Repair the wiring harness.
AC303802
Connector: C-139

AE
C-139 (B)
Harness side
AC303802
Connector: C-139

AE
C-139 (B)
Harness side
AC301541EX
Connector C-139
(Harness side)
9
1
1574
12
1110
23
13
5
14616
8
AC303804
Connector: C-109

AE
Harness side
AC303804
Connector: C-109

AE
Harness side
AC303802
Connector: C-139

AE
C-139 (B)
Harness side

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-15
STEP 10. Connector check: A-31 dual pressure
switch connector
Q: Is the check result normal?
YES :
Go to Step 11.
NO : Repair the connector.
STEP 11. Check the dual pressure switch
operation.
Refer to P.55-69.
Q: Is the dual pressure switch operating properly?
YES :
Go to Step 12.
NO : Replace the dual pressure switch.
STEP 12. Connector check: C-106 air thermo
sensor connector
Q: Is the check result normal?
YES :
Go to Step 13.
NO : Repair the connector.
STEP 13. Check the wiring harness between
C-106 air thermo sensor connector (terminals 4
and 5) and C-139 A/C-ECU connector (terminals
16 and 13).
•Check the air thermo sensor output and earth line
for open or short circuit.
Q: Is the check result normal?
YES :
Go to Step 14.
NO : Repair the wiring harness.
AC303839
Connector: A-31

AH
Harness side
A-31 (BR)
AC303804
Connector: C-106

AC
C-106
AC303804
Connector: C-106

AC
C-106
AC303802
Connector: C-139

AE
C-139 (B)
Harness side

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-16
STEP 14. Check the wiring harness between A-31
dual pressure switch connector terminal No.1
and C-139 A/C-ECU connector terminal No.4.
NOTE:
Prior to the wiring harness inspection, check
intermediate connector C-114, and repair if
necessary.
•Check the dual pressure switch output line for
open or short circuit.
Q: Is the check result normal?
YES :
Go to Step 15.
NO : Repair the wiring harness.
STEP 15. Connector check: C-125 engine-ECU
connector or C-126 engine-A/T-ECU
connector
Q: Is the check result normal?
YES :
Go to Step 16.
NO : Repair the connector.
AC303839
Connector: A-31

AH
Harness side
A-31 (BR)
AC303802
Connector: C-139

AE
C-139 (B)
Harness side
AC303804
Connector: C-114

AN183
161514121745 8
20196721 2291025
1324 2312 11
AC303805
Connectors: C-125 , C-126
AG

C-126 (GR)
C-125Harness side
C-125 (Y)
C-126
38
46
45 44 43 42 41 40 3937 36 35 34 33 32 3177 76 75 74 73 72 71
78 79 80 81 82 83 84 85 86 87 88 89
90 98 97 96 95 94 93 92 91

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-17
STEP 16. Check the wiring harness between
C-125 engine-ECU connector terminal
No.45 or C-126 engine-A/T-ECU connector
terminal No.83 and A-31 dual pressure switch
connector terminal No.2.NOTE:
Prior to the wiring harness inspection, check
intermediate connector C-114 and C-15, and repair if
necessary.
•Check the communication line for open or short
circuit.
Q: Is the check result normal?
YES :
Go to Step 17.
NO : Repair the wiring harness.
AC303839
Connector: A-31

AH
Harness side
A-31 (BR)
AC303805
Connectors: C-125 , C-126
AG

C-126 (GR)
C-125Harness side
C-125 (Y)
C-126
38
46
45 44 43 42 41 40 3937 36 35 34 33 32 3177 76 75 74 73 72 71
78 79 80 81 82 83 84 85 86 87 88 89
90 98 97 96 95 94 93 92 91
AC303800
Connector: C-15

AE
C-15 (L)
AC303804
Connector: C-104

AB
C-104 (GR)

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-18
STEP 17. Connector check: C-123 engine-ECU
connector or C-124 engine-A/T-ECU
connector
Q: Is the check result normal?
YES :
Go to Step 18.
NO : Repair the connector.
STEP 18. Check the wiring harness between
C-123 engine-ECU connectors terminal No.24
or C-124 engine-A/T-ECU connectors
terminal No.61 and C-139 A/C-ECU
connector terminal No.5.
AC303805
Connectors: C-123 , C-124

C-124 Harness side
C-123
AF
C-124 (GR)
C-123 (Y)
46 45 44 43 42 41
57 56 55 54 53 52 515049 48 47
66 65 64 63 62 61 60 59 58
AC303805
Connectors: C-123 , C-124

C-124 Harness side
C-123
AF
C-124 (GR)
C-123 (Y)
46 45 44 43 42 41
57 56 55 54 53 52 515049 48 47
66 65 64 63 62 61 60 59 58
AC303802
Connector: C-139

AE
C-139 (B)
Harness side

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-19
NOTE:
Prior to the wiring harness inspection, check
intermediate connector C-15, and repair if necessary.
•Check the communication line for open or short
circuit.
Q: Is the check result normal?
YES :
Go to Step 19.
NO : Repair the wiring harness.
STEP 19. Check the magnetic clutch operation.
Refer to P.55-93.
Q: Can the sound of the magnetic clutch (click) be
heard?
YES :
Go to Step 20.
NO : Replace the compressor magnet clutch.
STEP 20. Check the refrigerant temperature
switch.
Refer to P.55-95.
Q: Is the refrigerant temperature switch operating
properly?
YES :
Go to Step 21.
NO : Replace the refrigerant temperature switch.
STEP 21. Check the air thermo sensor.
Refer to P.55-90.
Q: Is the air thermo sensor in good condition?
YES :
Go to Step 22.
NO : Replace the air thermo sensor.
STEP 22. Check the refrigerant level.
Refer to P.55-69.
Q: Is the refrigerant level correct?
YES :
Go to Step 23.
NO : Correct the refrigerant level (Refer to
P.55-70).
STEP 23. Replace the A/C-ECU.
Check that the air conditioner works normally.
Q: Is the check result normal?
YES :
This diagnosis is complete.
NO : Replace the engine-ECU or the
engine-A/T-ECU .
AC303800
Connector: C-15

AE
C-15 (L)

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-20
INSPECTION PROCEDURE 4: When the A/C is Operating, Temperature Inside the Passenger
Compartment does not Decrease (Cool Air is not Emitted).
ENGINE-ECU
A/C-ECUDUAL
PRESSURE
SWITCH
RESISTOR ENGINE-A/T-ECU
HEATER CONTROL PANEL
Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Gray R : Red P : Pink V : Violet
AIR THERMO
SENSOR
NOTEM/T
A/T
A/C-ECU System Circuit