Mitsubishi Evolution X. Manual - part 1271

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-35

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958. Refer to "How to connect the 

Scan Tool (M.U.T.-III) 

P.55-7

."

(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO :  Repair the CAN bus line. (Refer to GROUP 54C, 

Diagnosis 

P.54C-14

).

STEP 2. Recheck for diagnostic trouble code.
Recheck if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to "ON" position.
(3) Check if the DTC is set.
Q: Is the DTC set?

YES : Go to Step 3. 
NO :  It can be assumed that this malfunction is intermittent. 

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

− How to 

Cope with Intermittent Malfunctions 

P.00-15

.

STEP 3. Check A/C pressure sensor connector A-53 and 
A/C-ECU connector C-22 for loose, corroded or damaged 
terminals, or terminals pushed back in the connector.
Q: Are air A/C pressure sensor connector A-53 and 

A/C-ECU connector C-22 in good condition?
YES : Go to Step 4.
NO :  Repair or replace the connector. Refer to GROUP 

00E, Harness Connector Inspection 

P.00E-2

.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-36

STEP 4. Check the wiring harness between A/C-ECU 
connector C-22 (terminals 20, 16 and 19) and A/C pressure 
sensor connector A-53 (terminals 3, 2 and 1).
NOTE: Also check intermediate connector C-131 and joint con-
nector C-102 for loose, corroded, or damaged terminals, or ter-
minals pushed back in the connector. If intermediate connector 
C-131 and joint connector C-102 is damaged, repair or replace 
the connector as described in GROUP 00E, Harness Connec-
tor Inspection 

P.00E-2

.

Q: Is the wiring harness between A/C-ECU connector C-22 

(terminals 20, 16 and 19) and A/C pressure sensor 
connector A-53 (terminals 3, 2 and 1) in good condition?
YES : Go to Step 5.
NO :  Repair the wiring harness.

STEP 5. Check the A/C pressure sensor operation.
(1) Assemble a gauge manifold on the high pressure service 

valve.

(2) Disconnect the A/C pressure sensor connector and connect 

special tool test harness MB991658 as shown in the 
illustration.

(3) Turn ON the engine and then turn ON the A/C switch.

(4) At this time, check to see that the voltage of A/C pressure 

sensor terminal No. 2 reflects the specifications of the 
figure.
NOTE: The allowance shall be defined as 

±

5%.

Q: Is the A/C pressure sensor operating properly?

YES : Go to Step 6.
NO :  Replace the A/C pressure sensor. Then go to Step 7.

AC609413

A/C pressure sensor

AB

AC307368

A/C 
pressure 
sensor 
side

MB991658

AC

Harness side

AC208297AG

Refrigerant pressure MPa (psi)

Output voltage 

(V)

0

1

2

3

5

4

1 (145)

2 (290)

3 (435)

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-37

STEP 6. Check the refrigerant level.
Use the refrigerant recovery station to remove all of the refrig-
erant, and then calculate the amount of the refrigerant and 
charge it.
Q: Is the refrigerant level correct?

YES : Go to Step 7.
NO :  Correct the refrigerant level (Refer to On-vehicle 

Service 

P.55-114

). Then go to Step 7. 

STEP 7. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect scan tool MB991958 to the data link connector
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?

YES : Return to Step 1.
NO :  The procedure is complete.

DTC B2214: Control Panel Failure

A/C Control Panel Circuit

A/C-ECU

A/C
CONTROL
PANEL

CPU

INTERFACE
CIRCUIT

AC708601

AUTO A/C DIAGNOSIS

TSB Revision

HEATER, AIR CONDITIONING AND VENTILATION

55-38

.

DTC SET CONDITION

DTC B2214 will be set when the A/C-ECU detects the A/C con-
trol panel abnormality.

.

TECHNICAL DESCRIPTION (COMMENT)

Current trouble

• The A/C-ECU, the A/C control panel, or connector(s) or wir-

ing between the two may be defective.

Past trouble

• If DTC B2214 is stored as a past trouble, carry out diagno-

sis with particular emphasis on wiring and connector(s) 
between the A/C-ECU and the A/C control panel. If the con-
nectors and wiring are normal, and obviously the ECU is the 
cause of the trouble, replace the ECU. If in doubt, do not 
replace the ECU.

.

TROUBLESHOOTING HINT

• Malfunction of connector.

• Malfunction of the harness.

• Malfunction of the A/C control panel.

• Malfunction of the A/C-ECU.

DIAGNOSIS

Required Special Tool:

•  MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicle Communication Interface (V.C.I.)

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

AC708951AJ

Connectors: C-22, C-123

C-123

C-22 (B)