AMOUNT OF AIR BLOWN FROM REAR VENTS DOES NOT CHANGE [CLIMATE CONTROL SYSTEM]

id0703k2900800

DESCRIPTION
•  Malfunction in rear blower system
POSSIBLE CAUSE
•  R.HEATER 40 A fuse malfunction
•  Rear blower unit malfunction
•  Open or short circuit in wiring harness between rear climate control unit and rear blower relay
•  Rear blower relay malfunction
•  Rear blower motor malfunction
•  Power MOS FET malfunction
•  Rear climate control unit malfunction
•  When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while performing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, inspect make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic Procedure

Step

Inspection

Action
1
INSPECT FUSE
•  Switch the ignition off.
•  Disconnect the negative battery terminal.
•  Remove the R.HEATER 40 A fuse.
•  Is the fuse normal?
Yes
Go to the next step.
No
If the fuse is blown:
•  Refer to the wiring diagram and verify whether or not there is a common connector between R.HEATER 40 A fuse and rear blower motor / rear blower relay terminal.
If there is a common connector:
?  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
?  Repair or replace the malfunctioning part.
If there is no common connector:
?  Repair or replace the wiring harness which has a short to ground.
•  Replace the fuse.
If the fuse is damaged:
•  Replace the fuse.
Then go to Step 15.
2
INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR BLOWER UNIT OR ELSEWHERE
•  Connect the negative battery terminal.
•  Switch the ignition ON (engine off or on).
•  Turn the airflow volume control switch on.
•  Does the rear blower motor rotate?
Yes
Go to the next step.
No
Go to Step 4.
3
INSPECT REAR BLOWER UNIT INTAKE VENT
•  Is rear blower unit intake vent restricted?
Yes
Remove obstruction, then go to Step 15.
No
Inspect if there are any obstruction in the rear A/C unit passage, then go to Step 15.
4*
INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR BLOWER RELAY SYSTEM OR POWER MOS FET
•  Turn the rear airflow volume control switch on.
•  Measure the voltage at the following terminal (wiring harness side).
?  Rear blower motor terminal A (rear blower motor operation signal)
•  Is voltage B+?
Yes
Go to Step 9.
No
Go to the next step.
5*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN FUSE BLOCK AND REAR BLOWER RELAY) OR ELSEWHERE
•  Measure the voltage at the following terminals (wiring harness side).
?  Rear blower relay terminal A (B+ signal)
?  Rear blower relay terminal D (B+ signal)
•  Is the voltage B+?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between rear blower relay terminal and R.HEATER 40 A fuse.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness.
Go to Step 15.
6*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN REAR BLOWER RELAY AND GROUND) OR ELSEWHERE
•  Measure the voltage at the following terminal (wiring harness side).
?  Rear blower relay terminal E (ground)
•  Is the voltage approx. 0 V?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between rear blower relay terminal and front body control module (FBCM) terminal.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness.
Go to Step 15.
7*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN REAR BLOWER RELAY AND REAR BLOWER MOTOR) OR REAR BLOWER RELAY
•  Measure the voltage at the following terminal (wiring harness side).
?  Rear blower relay terminal C (rear blower motor operation signal)
•  Is the voltage B+?
Yes
Go to the next step.
No
Replace the rear blower relay, then go to Step 15.
(See RELAY LOCATION.)
8*
INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR BLOWER MOTOR OR ELSEWHERE
•  Measure the voltage at the following terminal (wiring harness side).
?  Rear blower motor terminal B (rear blower motor operation signal)
•  Is the voltage B+?
Yes
Inspect the rear blower motor, then go to Step 15.
(See REAR BLOWER MOTOR INSPECTION.)
No
Repair the wiring harness for lack of continuity between the rear blower relay and rear blower motor, then go to Step 15.
9*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN REAR BLOWER MOTOR AND POWER MOS FET) OR ELSEWHERE
•  Measure the voltage at the following terminal (wiring harness side).
?  Power MOS FET terminal B (rear blower motor operation signal)
•  Is voltage B+?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between rear blower motor terminal and power MOS FET terminal.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness.
Go to Step 15.
10*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER MOS FET AND GROUND) OR ELSEWHERE
•  Measure the voltage at the following terminal (wiring harness side).
?  Power MOS FET terminal A (ground)
•  Is the voltage approx. 0 V?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between power MOS FET terminal and ground.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness.
Go to Step 15.
11
INSPECT REAR BLOWER UNIT
•  Inspect the fan in rear blower unit.
?  Is the fan free of interference with the rear blower unit case?
?  Is the fan free of foreign matter and obstructions?
•  Is the fan normal?
Yes
Go to the next step.
No
Remove obstruction, repair or replace the fan and rear blower unit case, then go to Step 15.
12*
INSPECT POWER MOS FET
•  Inspect the power MOS FET.
•  Is the power MOS FET normal?
Yes
Go to the next step.
No
Replace the power MOS FET, then go to Step 15.
(See POWER METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR (POWER MOS FET) REMOVAL/INSTALLATION.)
13*
INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER MOS FET AND REAR CLIMATE CONTROL UNIT) OR ELSEWHERE
•  Switch the ignition off.
•  Disconnect the negative battery terminal.
•  Disconnect rear climate control unit connector.
•  Inspect for continuity between the following terminals (wiring harness-side).
?  Power MOS FET terminal C—rear climate control unit terminal H
?  Power MOS FET terminal D—rear climate control unit terminal F
•  Is there continuity?
Yes
Go to the next step.
No
Refer to the wiring diagram and verify whether or not there is a common connector between power MOS FET terminal and rear climate control unit terminal.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness.
Go to Step 15.
14*
INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR CLIMATE CONTROL UNIT OR WIRING HARNESS (SHORT TO GROUND IN WIRING HARNESS BETWEEN POWER MOS FET AND REAR CLIMATE CONTROL UNIT)
•  Inspect for continuity between the following terminals (wiring harness-side) and body ground.
?  Power MOS FET terminal C
?  Power MOS FET terminal D
•  Is there continuity?
Yes
Refer to the wiring diagram and verify whether or not there is a common connector between power MOS FET terminal and rear climate control unit.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has a short to ground.
Go to the next step.
No
Replace the rear climate control unit, then go to the next step.
(See REAR CLIMATE CONTROL UNIT REMOVAL/INSTALLATION.)
15
VERIFY THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR
•  Is air discharged from vent?
Yes
Troubleshooting completed.
Explain repairs to customer.
No
Recheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.