2005 MITSUBISHI 380 Workshop Manual

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-100
STEP 17. Replace the power transistor.
Q: Does the blower motor operate normally?
YES : No action is necessary and testing is complete.
NO : Replace the A/C-ECU. Check that the air conditioning
works normally.
INSPECTION PROCEDURE 6: Front 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
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90
DIAGNOSIS
Required Special Tool:
MB991223: Test Harness Set
STEP 1. Check blower power transistor connector C-104
for loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is power transistor connector C-104 in good condition?
YES : Go to Step 2.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2.The
blower motor should operate normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-101
STEP 2. Measure the resistance at power transistor
connector C-104.
(1) Disconnect power transistor connector C-104, 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 4.
NO : Go to Step 3.
STEP 3. Check the wiring harness between power
transistor connector C-104 (terminal 2) and ground.
Q: Is the wiring harness between power transistor
connector C-104 (terminal 2) and ground in good
condition?
YES : The blower motor should operate normally.
NO : Repair the wiring harness. The blower motor should
operate normally.
STEP 4. 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 5.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2.The
blower motor should operate normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-102
STEP 5. Check the wiring harness between power
transistor connector C-104 (terminal 4) and blower motor
connector C-115 (terminal 2).
Q: Is the wiring harness between power transistor
connector C-104 (terminal 4) and blower motor
connector C-115 (terminal 2) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. The blower motor should
operate normally.
STEP 6. Check A/C-ECU connector C-15 for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is A/C-ECU connector C-15 in good condition?
YES : Go to Step 7.
NO : Repair or replace the connector. Refer to GROUP
00E, Harness Connector Inspection P.00E-2.The
blower motor should operate normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-103
STEP 7. Check the wiring harness between power
transistor connector C-104 (terminals 1 and 3) and
A/C-ECU connector C-15 (terminals 17 and 18).
Q: Are the wiring harness between power transistor
connector C-104 (terminals 1 and 3) and A/C-ECU
connector C-15 (terminals 17 and 18) in good condition?
YES : Go to Step 8.
NO : Repair the wiring harness. The blower motor should
operate normally.
STEP 8. Replace the power transistor.
Q: Does the blower motor operate normally?
YES : 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.00-14.
NO : Replace the A/C-ECU. Check that the air conditioning
works normally.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-104
INSPECTION PROCEDURE 7: The A/C Indicator Flashes.
.
TECHNICAL DESCRIPTION (COMMENT)
If the A/C indicator flashes, inadequate refrigerant
quantity, the ambient air temperature sensor circuit
or the A/C pressure sensor circuit is suspected.
.
TROUBLESHOOTING HINTS
Malfunction of the A/C pressure sensor
Malfunction of the ambient air temperature sen-
sor
Malfunction of the A/C-ECU
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90
DIAGNOSIS
Required Special Tools:
MB991223: Test Harness Set
: Scan Tool (MUT-III Sub Assembly)
MB991824: Vehicle Communication Interface (V.C.I.)
MB991827: MUT-III USB Cable
MB991910: MUT-III Main Harness A (Vehicles with CAN
communication system)
STEP 1. Using scan tool , read the diagnostic trouble code.
Check if an A/C-ECU DTC is set.
(1) Connect scan tool 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 check result satisfactory?
YES : Go to Step 2.
NO : Refer to DIAGNOSTIC TROUBLE CODE CHART
P.55-9.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-105
STEP 2. Using scan tool , check data list item 61: A/C
pressure sensor.
To prevent damage to scan tool , always turn the ignition
switch to the "LOCK" (OFF) position before connecting or
disconnecting scan tool .
(1) Connect scan tool to the data link connector.
(2) Assemble a manifold gauge onto the high pressure service
valve.
(3) Turn ON the engine and then turn ON the air conditioner
switch.
(4) Set scan tool to the data reading mode for item 61: A/C
pressure sensor.
Check that the refrigerant pressure matches the dis-
played value on the scan tool.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor within the specified range?
YES : Go to Step 7.
NO : Go to Step 3.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-106
STEP 3. Check A/C pressure sensor connector A-30 for
loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is A/C pressure sensor connector A-30 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.

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-107
STEP 4. Check the A/C pressure sensor.
(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 air conditioner
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 in good condition?
YES : Go to Step 5.
NO : Replace the A/C pressure sensor. Check that the air
conditioning works normally.