Mitsubishi Galant (2004+). Manual - part 764

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

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STEP 7. Check powertrain control module connector B-21 
and A/C compressor assembly B-28 for loose, corroded or 
damaged terminals, or terminals pushed back in the 
connector.

Q:  Are powertrain control module connector B-21 and A/C 

compressor assembly B-28 in good condition?
YES : Go to Step 8.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

. Check 

that the air conditioning works normally.

AC305216

B-21 (B)

AC

CONNECTOR: B-21 <2.4L>

HARNESS SIDE

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AC305229

B-21 (B)

AB

HARNESS SIDE

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CONNECTOR: B-21 <3.8 L>

AC305214

B-28 (B)

HARNESS SIDE

AD

CONNECTOR: B-28 <2.4L>

AC305218

B-28 (B)

HARNESS SIDE

AB

CONNECTOR: B-28 <3.8 L>

MANUAL A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55A-196

STEP 8. Measure the voltage at A/C compressor assembly 
connector B-28. 

(1) Disconnect A/C compressor assembly connector B-28 and 

measure the voltage at the relay box side.

AC305214

B-28 (B)

HARNESS SIDE

AD

CONNECTOR: B-28 <2.4L>

AC305218

B-28 (B)

HARNESS SIDE

AB

CONNECTOR: B-28 <3.8 L>

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

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(2) Disconnect powertrain control module connector B-21 and 

ground harness side terminal No.81.

(3) Turn the ignition switch to the "ON" position.

(4) A/C compressor assembly connector B-28 terminal 1 and 

ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 15.
NO :   Go to Step 9.

AC305216

B-21 (B)

AC

CONNECTOR: B-21 <2.4L>

HARNESS SIDE

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AC305229

B-21 (B)

AB

HARNESS SIDE

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CONNECTOR: B-21 <3.8 L>

AC306468

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AC306468

CONNECTOR B-21 
(HARNESS SIDE)

AD

AC209365

CONNECTOR B-28 
(HARNESS SIDE)

GS

MANUAL A/C DIAGNOSIS

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HEATER, AIR CONDITIONING AND VENTILATION

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STEP 9. Measure the voltage at A/C compressor clutch 
relay connector B-18X. 

CAUTION

The top and bottom of the A/C compressor connector are 
difficult to identify. Prior to inspection, confirm the triangle 
mark on the relay box.
(1) Disconnect A/C compressor connector B-18X and measure 

the voltage at the relay box side.

(2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 2 and ground.

• The measured value should be approximately 12 volts 

(battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES :  Go to Step 11.
NO :   Go to Step 10.

STEP 10. Check the wiring harness between A/C 
compressor clutch relay connector B-18X (terminal 2) and 

the ignition switch (IG2).

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 
TRIANGLE MARK

AC209365GT

CONNECTOR B-18X 
(RELAY BOX SIDE)

AC305977AJ

CONNECTOR: B-18X

RELAY BOX SIDE

FRONT OF 
VEHICLE

JUNCTION BLOCK 
TRIANGLE MARK