Mitsubishi Galant (2004+). Manual - part 753

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-151

STEP 15. Measure the resistance at blower motor 
connector C-115 in order to the ground circuit to the 
blower motor.

(1) Disconnect blower motor connector C-115, and measure 

the resistance at the wiring harness side.

(2) Measure the resistance value between terminal 2 and 

ground.

• The measured value should be 2 ohms or less.

Q: Does the measured resistance value correspond with 

this range?
YES :  Go to Step 17.
NO :   Go to Step 16.

STEP 16. Check the wiring harness between blower motor 
connector C-115 (terminal 2) and ground.

Q: Is the wiring harness between blower motor connector 

C-115 (terminal 2) and ground in good condition?
YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-6

.

NO :  Repair the wiring harness. The blower motor should 

operate normally.

STEP 17. Check the blower fan and motor operation.

When battery voltage is applied between the terminals, check 
that the motor operates. Also, check that there is no abnormal 
noise.
Q: Is there any abnormal noise?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-6

.

NO :  Replace the blower relay. The blower motor should 

operate normally.

AC305233BN

CONNECTOR: C-115

HARNESS SIDE

AC209364

CONNECTOR C-115 
(HARNESS SIDE)

IT

AC305233BN

CONNECTOR: C-115

HARNESS SIDE

AC209862

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-152

INSPECTION PROCEDURE 6: Blower Air Amount cannot be Changed.

.

CIRCUIT OPERATION
If the blower motor speed cannot be changed, the 
power transistor circuit is suspected.

.

TROUBLESHOOTING HINTS

• Malfunction of the power transistor

• Malfunction of the front A/C-ECU

• Damaged harness wires or connectors

BLOWER RELAY

BLOWER 
SWITCH

RESISTOR

BLOWER
MOTOR

Blower Switch and Resistor Circuit

AC305233BR

CONNECTORS: C-14, C-103, C-115

C-103

C-115

C-14

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-153

DIAGNOSIS

Required Special Tool:

• MB991223: Test Harness Set

STEP 1. Check resistor connector C-103 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q:  Is resistor connector C-103 in good condition?

YES : Go to Step 2.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

STEP 2. Check the resistor resistance value.

Use an ohmmeter to measure the resistance between the ter-
minals. Check that the measured value is at the standard 
value.

Standard value:

Q: Is the measured value at the standard value?

YES : Go to Step 3.
NO :  Replace the resistor. The blower motor should 

operate normally.

STEP 3. Check blower motor connector C-115 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q:  Is blower motor connector C-115 in good condition?

YES : Go to Step 4.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

AC305233

HARNESS SIDE

BQ

CONNECTOR: C-103

MEASUREMENT TERMINAL

STANDARD VALUE 

Ω

Between terminals 2 and 3 (LO)

2.79

Between terminals 1 and 2 (ML) 1.49

Between terminals 2 and 4 (MH) 0.39

AC307313

1 2

3 4

AC305233BN

CONNECTOR: C-115

HARNESS SIDE

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-154

STEP 4. Check the wiring harness blower switch 
connector C-115 (terminal 1) and resistor connector C-103 
(terminal 2).

Q: Is the wiring harness between blower switch connector 

C-115 (terminal 1) and resistor connector C-103 
(terminal 2) in good condition?
YES : Go to Step 5.
NO :  Repair the wiring harness. The blower motor should 

operate normally.

STEP 5. Check blower switch connector C-14 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.

Q:  Is blower switch connector C-14 in good condition?

YES : Go to Step 6.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

AC305234

CONNECTORS: C-103, C-115

C-103

C-115

HARNESS SIDE

C-103

HARNESS SIDE

C-115

AK

AC305233

HARNESS SIDE

BO

CONNECTOR: C-14