Mitsubishi Galant. Manual — part 721

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-10

STEP 2. 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 there is
continuity between the respective terminals.

Q: When the high/low pressure sides of the dual pressure

switch are at operation pressure (ON), is there
continuity between the respective terminals?
YES : Go to Step 3.
NO : Replace the switch. Then go to Step 6.

STEP 3. Check the refrigerant-temperature switch
operation.

Q: When the A/C is off, check that there is continuity

between the refrigerant-temperature switch terminals. Is
the circuit open loop?
YES : Replace the switch. Then go to Step 6.
NO : If less than two ohm, go to Step 4.

STEP 4. Measure the automatic compressor controller
terminal voltage.
Refer to

P.55-17

.

Q: Is the automatic compressor controller terminal voltage

in good condition?
YES : Go to Step 5.
NO : Replace. Then go to Step 6.

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

AC001372

REFRIGERANT
TEMPERATURE
SWITCH TERMINALS

AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-11

STEP 5. Measure the engine control module <M/T>/the
powertrain control module <A/T> terminal voltage.
(1) 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

(2) Refer to GROUP 13B, Diagnosis

−

Check at The

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

P.13A-417

Q: Is the voltage in good condition?

YES : Go to Step 6.
NO : Replace. Then go to Step 6.

STEP 6. Check symptoms.

Q: Is the cool air discharged?

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 4: BLOWER FAN AND MOTOR DOES NOT TURN.

DIAGNOSIS

STEP 1. Check the blower relay continuity.

Q: Is the blower relay continuity in good condition?

YES : Go to Step 2.
NO : Replace. Then go to Step 5.

BATTERY
VOLTAGE

TERMINAL NO.
TO BE
CONNECTED TO
BATTERY

TERMINAL NO.
TO BE
CONDUCTED

SUPPLIED

1-3

2-5

NOT SUPPLIED

-

1-3

AC003706 AB

BLOWER RELAY

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-12

STEP 2. Check the blower fan and motor operation.
When battery voltage is applied between the terminals, check
that the motor operates.

Q: Is there any abnormal noise?

YES : Go to Step 3.
NO : Replace. Then go to Step 5.

STEP 3. Check the blower switch continuity.

Q: Is the blower switch continuity in good condition?

YES : Go to Step 4.
NO : Replace. Then go to Step 5.

STEP 4. Check the resistor resistance value.
Use an ohmmeter to measure the resistance between the
terminals as indicated below. 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 5.
NO : Replace. Then go to Step 5.

AC001377AB

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

MEASUREMENT TERMINAL

STANDARD VALUE

Ω

Ω

Ω

Ω

Between terminals 3 and 2 (LO)

2.3

Between terminals 3 and 4 (ML)

1.1

Between terminals 3 and 1 (MH)

0.4

AC001379AB

MANUAL A/C DIAGNOSIS

TSB Revision

HEATING AND AIR CONDITIONING

55-13

STEP 5. Check symptoms.

Q: Is the blower fan and motor turned?

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 5: BLOWER FAN AND MOTOR DOES NOT STOP TURNING.

DIAGNOSIS

STEP 1. Check the harness wire between the blower fan
and motor connector C-11, the resistor connector C-14,
and the blower switch connector C-53.

Q: Is the harness wire between the blower fan and motor

connector C-11, the resistor connector C-14, and the
blower switch connector C-53 in good condition?
YES : Go to Step 2.
NO : Repair it. Then go to Step 4.

AC003733

CONNECTORS: C-11, C-14, C-53

AB

C-11

C-14

C-53