2005 MITSUBISHI LANCER engine

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-25
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.1.
NOTE:
Prior to the wiring harness inspection, check
intermediate connector C-28, 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.
AC303825
Connector: A-31

AH
A-31 (BR)
Harness side
AC303818
Connector: C-139

AJ
Harness side
C-139 (B)
11 12657 8 9 103 421
AC303814
Connector: C-28

AJ
AC303817
Connectors: C-125 , C-126
AH

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 VENTILATION55-26
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-28 and C-135, 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.
AC303825
Connector: A-31

AH
A-31 (BR)
Harness side
AC303817
Connectors: C-125 , C-126
AH

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
AC303814
Connector: C-28

AJ
AC303818
Connector: C-135

AH
C-135 (L)

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-27
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.2.
•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.
AC303817
Connectors: C-123 , C-124
AG

C-123 (Y)
C-123Harness side
C-124 (GR)
46 45 44 43 42 41
57 56 55 54 53 52 515049 48 47
66 65 64 63 62 61 60 59 58
C-124
AC303817
Connectors: C-123 , C-124
AG

C-123 (Y)
C-123Harness side
C-124 (GR)
46 45 44 43 42 41
57 56 55 54 53 52 515049 48 47
66 65 64 63 62 61 60 59 58
C-124
AC303818
Connector: C-139

AJ
Harness side
C-139 (B)
11 12657 8 9 103 421

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-28
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
On-vehicle Service 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 .

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-59
INSPECTION PROCEDURE 11: A/C Compressor power supply system.
A/C
COMPRESSOR
RELAY
A/C
COMPRESSOR
A/C
REFRIGERANT
TEMPERATURE
SWITCH
MAGNETIC
CLUTCH
IGNITION
SWITCH (IG2)
ENGINE-ECU BATTERY
RELAY
BOX
ENGINE-A/T-ECU
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
: M/T
: A/TNOTE
A/C Compressor Circuit

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-65
•Check the A/C compressor power supply line for
open circuit.
Q: Is the check result normal?
YES :
Go to Step 10.
NO : Repair the wiring harness.
STEP 10. Connector check: C-123 engine-ECU
connector or C-122 engine-A/T-ECU
connector
Q: Is the check result normal?
YES :
Go to Step 11.
YES : Go to Step 12.
NO : Repair the connector.
AC303786
Connector: B-114
<4G1-R.H.D.>
AB
Harness side
B-114 (B)
AC303794
Connector: B-114
<4G6-R.H.D.>
AB
Harness side
B-114 (B)
AC303805
Connectors: C-122 , C-123

C-122 (GR)
C-123 (Y)
C-122 Harness side
C-123
AE
AC303817
Connectors: C-122 , C-123
AF

C-122C-122 (GR)
C-123 (Y)
C-123 Harness side

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-66
STEP 11. Check the wiring harness between
C-123 engine-ECU connector terminal No.8 and
B-17X A/C compressor relay connector terminal
No.3.
•Check the A/C compressor relay earth line for
open circuit.
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.
STEP 12. Check the wiring harness between
C-122 engine A/T-ECU connector terminal No.20
and B-17X A/C compressor relay connector
terminal No.3.
•Check the A/C compressor relay earth line for
open or short circuit.
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.
AC304988AB
Connector: B-17X
Front of
vehicle
1
3 2
4
Relay box side
AC303804
Connector: C-123

AH
Harness side
C-123 (Y)
AC303816
Connector: C-123
AM

Harness side
C-123 (Y)
AC304988AB
Connector: B-17X
Front of
vehicle
1
3 2
4
Relay box side
AC303804
Connector: C-122

AG
Harness side
C-122 (GR)
AC303816
Connector: C-122
AL

Harness side
C-122 (GR)

TROUBLESHOOTING
HEATER, AIR CONDITIONER AND VENTILATION55-67
CHECK AT ECU TERMINAL M1552010300527
12
345
678
9 10111213141516
AC300861AC

Terminal No. Check item Checking requirement Normal condition
1 Rear defogger switch Defogger switch: ON 0 V
Defogger switch: OFF System voltage
2 Inside/outside air selection
damper motor (outside air)When the damper is moved to
the inside air recirculation
position0 V
When the damper is moved to
the outside air inside air intake
positionSystem voltage
3 Inside/outside air selection
damper motor (inside air)When the damper is moved to
the inside air recirculation
positionSystem voltage
When the damper is moved to
the outside air inside air intake
position0 V
4 Output to the engine-A/T-ECU
(A/C1)A/C stopped 0 V
•A/C switch: ON
•Blower switch: ONSystem voltage
5 Output to the engine-A/T-ECU
(A/C2)When the A/C is under low load System voltage
When the A/C is under high
load0 V
6 Power supply to the A/C
illuminationLighting switch: ON System voltage
7---
8 Blower switch (lo) blower switch: lo System voltage
9---
10 Power supply to the ignition
switch (IG2)Ignition switch: ON System voltage
11 Earth to the A/C illumination Always 0 V
12 Earth Always 0 V
13 Air thermo sensor (outlet side) Sensor probe temperature 25°C
(1.5k ohm)2.2 V
14, 15 - - -
16 Earth to the air thermo sensor Always 0 V