Mitsubishi Galant. Manual — part 720

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-6

STEP 3. Check the A/C compressor relay continuity.

Q: Is the A/C compressor relay in good condition?

YES : Go to Step 4.
NO : Replace. Then go to Step 11.

STEP 4. Check the magnetic clutch operation.
Connect the battery (+) terminal to the compressor magnetic
clutch connector terminal 1; <2.4L engine>/terminal 4; <3.0L
engine>, and ground the battery (-) terminal to the body of the
compressor.

Q: Can the sound of the magnetic clutch (click) be heard?

YES : Go to Step 5.
NO : Replace. Then go to Step 11.

BATTERY
VOLTAGE

TERMINAL NO.
TO BE
CONNECTED TO
BATTERY

TERMINAL NO.
TO BE
CONDUCTED

SUPPLIED

1-3

4-5

NOT SUPPLIED

-

1-3

AC001366 AB

A/C COMPRESSOR RELAY

AC001367

1 2

3 4

AB

<2.4L ENGINE>

<3.0L ENGINE>

MAGNETIC CLUTCH
CONNECTOR

MAGNETIC CLUTCH
CONNECTOR

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-7

STEP 5. Check the dual pressure switch operation.
(1) Remove the dual pressure switch connector and connect

the high/low pressure side terminals located on the harness
side as shown in the illustration.

(2) Install a gauge manifold to the high-pressure side service

valve of the refrigerant line. (Refer to

P.55-22

.)

(3) When the high/low pressure sides of the dual pressure

switch are at operation pressure (ON) and the resistance is
less than two ohm between the respective terminals, then
the condition is normal. If open loop, replace the switch.

Q: Is the dual pressure switch operating properly?

YES : Go to Step 6.
NO : Replace the switch. Then go to Step 11.

STEP 6. Check the A/C switch continuity.

Q: Is the A/C switch continuity in good condition?

YES : Go to Step 7.
NO : Replace. Then go to Step 11.

STEP 7. Check the blower switch continuity.

Q: Is the blower switch continuity in good condition?

YES : Go to Step 8.
NO : Replace. Then go to Step 11.

ITEMS

SWITCH POSITION

OFF

→

→

→

→

ON

ON

→

→

→

→

OFF

Low-pressure side kPa
(psi)

221 (32.1)

196 (28.4)

High-pressure side kPa
(psi)

2,354 (341.4)

2,942 (426.7)

A003021

HIGH/LOW
PRESSURE SIDE

LOW-PRESSURE
SIDE

HIGH-PRESSURE
SIDE

ON

OFF

ON

OFF

AB

SWITCH
POSITION

TESTER
CONNECTION
(CONNECTOR B)

SPECIFIED
CONDITION

Off

-

No continuity

On

5-6-7

Continuity

AC001370

OFF

ON

BLOWER
SWITCH
ASSEMBLY

AB

SWITCH
POSITION

TESTER
CONNECTION
(CONNECTOR A)

SPECIFIED
CONDITION

0 (OFF)

-

No continuity

1 (LO)

3-5

Continuity

2 (ML)

1-3

Continuity

3 (MH)

3-6

Continuity

4 (HI)

3-4

Continuity

AC001371

BLOWER SWITCH
ASSEMBLY

AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-8

STEP 8. Check the refrigerant-temperature switch
operation.
When the A/C is off, check that there is less than 2

Ω

between

the refrigerant-temperature switch terminals.

Q: Is the refrigerant-temperature switch in good condition?

YES : Go to Step 9.
NO : If the switch has an open circuit, replace the switch.

Then go to Step 11.

STEP 9. Measure the automatic compressor controller
terminal voltage.
Refer to

P.55-17

.

Q: Is the automatic compressor controller terminal voltage

good?
YES : Go to Step 10.
NO : Replace. Then go to Step 11.

STEP 10. Measure the engine control module <M/T>/the
powertrain control module <A/T> terminal voltage.
Refer to GROUP 13A, Diagnosis

−

Check at The Engine

Control Module (ECM) <M/T> or Powertrain Control Module
(PCM) <A/T> <2.4L engine>

P.13A-417

Refer to GROUP 13B, Diagnosis

−

Check at The Powertrain

Control Module (PCM) <A/T> <3.0L engine>

P.13B-499

Q: Is the terminal voltage in good condition?

YES : Go to Step 11.
NO : Replace. Then go to Step 11.

STEP 11. Check symptoms.

Q: Is the A/C operating properly?

YES : This diagnosis is complete. (If no malfunctions are not

found in all steps, an intermittent malfunction is
suspected. Refer to Introduction, How to Use
Troubleshooting/Inspection Service Points

−

How to

Cope with Intermittent Malfunction

P.00-8

.)

NO : Go to Step 1.

AC001372

REFRIGERANT
TEMPERATURE
SWITCH TERMINALS

AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-9

INSPECTION PROCEDURE 2: WHEN THE AIR OUTLET CHANGEOVER CONTROL KNOB IS MOVED
TO DEFROSTER OR DEFROSTER/FOOT POSITION, THE A/C OR THE INSIDE/OUTSIDE AIR
CHANGEOVER DAMPER MOTOR DOES NOT OPERATE.

DIAGNOSIS

STEP 1. Check the defroster switch continuity.

Q: Is the defroster switch in good condition?

YES : Go to Step 2.
NO : Replace. Then go to Step 2.

STEP 2. Check each A/C part.
Refer to Inspection Procedure 1.

Q: Is the A/C operating properly?

YES : This diagnosis is complete. (If no malfunctions are not

found in all steps, an intermittent malfunction is
suspected. Refer to Introduction, How to Use
Troubleshooting/Inspection Service Points

−

How to

Cope with Intermittent Malfunction

P.00-8

.)

NO : Go to Step 1.

INSPECTION PROCEDURE 3: WHEN THE A/C IS OPERATING, TEMPERATURE INSIDE THE
PASSENGER COMPARTMENT DOES NOT DECREASE (COOL AIR NOT EMITTED).

DIAGNOSIS

STEP 1. Check for refrigerant leaks.

Q: Is the refrigerant leaking?

YES : Repair. Then go to Step 6.
NO : Go to Step 2.

AIR OUTLET
CHANGEOVER
CONTROL KNOB
POSITION

TESTER
CONNECTION

SPECIFIED
CONDITION

DEFROSTER,
DEFROSTER/
FOOT

2-3

Continuity

OTHER POSITION 1-3

Continuity

AC001373

HEATER
CONTROL
ASSEMBLY

AB