NO.7 AMOUNT OF AIR FROM REAR VENTS DOES NOT CHANGE

id070300901500

7 | Amount of air from rear vents does not change
DESCRIPTION | • Malfunction in rear blower motor system • Amount of air blowing rear vents does not change when switching front and/or rear climate control unit airflow volume control dial.
POSSIBLE CAUSE | • Rear A/C unit malfunction • Rear blower motor malfunction • Rear power MOS FET malfunction • Rear climate control unit malfunction

• When performing an asterisked (*) troubleshooting inspection, shake the wiring harness and connectors while doing the inspection to discover whether poor contact points are the cause of any intermittent malfunctions. If there is a problem, inspect to make sure connectors, terminals and wiring harness are connected correctly and undamaged.

Diagnostic procedure

STEP | INSPECTION | ACTION
--- | --- | ---
1 | INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR A/C UNIT OR ELSEWHERE • Turn the ignition switch to the ON position. • Turn the rear fan switch the ON position. • Does the blower motor rotate smoothly? | Yes | Go to the next step.
No | Go to Step 3.
2 | INSPECT REAR A/C UNIT INTAKE VENT • Is the rear A/C unit intake vent clogged? | Yes | Remove obstruction, then go to Step 13.
No | Inspect if there are any obstructions in the rear A/C unit passage, then go to Step 13.
3* | INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR BLOWER RELAY SYSTEM OR REAR POWER MOS FET • Turn the ignition switch to ON position. • Turn the rear fan switch to OFF position. • Measure the voltage at the following rear blower motor terminal. ― Terminal B (rear blower motor operation signal) • Is the voltage normal (B+)? | Yes | Go to the Step 7.
No | Go to the next step.
4* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN OR SHORT CIRCUIT BETWEEN FUSE BLOCK AND REAR BLOWER RELAY) OR ELSEWHERE • Measure the voltage at the following rear relay terminals. ― Terminal A (IG2 signal) ― Terminal D (B+ signal) • Is the voltage approx. 12 V? | Yes | Go to the next step.
No | If the terminal A voltage is not normal, repair or replace wiring harness between A/C 7.5 A fuse and rear blower relay. If the terminal D voltage is not normal, repair or replace wiring harness between R.HEATER 40 A fuse and rear blower relay. Then go to Step 13.
5* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN CIRCIT BETWEEN REAR BLOWER RELAY AND GROUND) OR ELSEWHERE • Measure the voltage at the following rear blower relay terminal. ― Terminal B (GND signal) • Is the voltage approx. 0 V? | Yes | Go to the next step.
No | Repair or replace for open circuit between rear blower relay and GND, then go to Step 13.
6* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN OR SHORT CIRCUIT BETWEEN REAR BLOWER RELAY AND REAR BLOWER MOTOR) OR ELSEWHERE • Measure the voltage at the following rear blower relay terminal. ― Terminal B (blower motor operation signal) • Is the voltage approx. 12 V? | Yes | Repair or replace for open or short circuit between rear blower relay and rear blower motor, then go to Step 13.
No | Replace the rear blower relay, then go to Step 13.
7* | INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR BLOWER MOTOR OR ELSEWHERE • Measure the voltage at the following rear blower motor terminal. ― Terminal A (blower motor operation signal) • Is the voltage approx. 12 V? | Yes | Go to the next step.
No | Replace the rear blower motor, then go to Step 13.
8* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN OR SHORT CIRCUIT BETWEEN REAR BLOWER MOTOR AND REAR POWER MOS FET) OR ELSEWHERE • Measure the voltage at the following rear power MOS FET terminal. ― Terminal B (blower motor operation signal) • Is the voltage approx. 12 V? | Yes | Go to the next step.
No | Repair or replace for open or short circuit between rear blower motor and rear power MOS FET, then go to Step 13.
9* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN CIRCUIT BETWEEN REAR POWER MOS FET AND GROUND) OR ELSEWHERE • Is there continuity at the following terminals? ― Terminal (wiring harness-side connector) A—GND | Yes | Go to the next step.
No | Repair or replace for open circuit between rear power MOS FET and GND, then go to Step 13.
10 | INSPECT REAR A/C UNIT • Inspect the fan in rear A/C unit. ― Is the fan free of interference with the rear A/C unit case? ― Is the fan free of foreign material and obstructions? • Is the fan normal? | Yes | Go to the next step.
No | Remove obstruction, repair or replace the fan blower unit case, then go to Step 13.
11* | INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (OPEN CIRCUIT BETWEEN REAR POWER MOS FET AND CLIMATE CONTROL UNIT) OR ELSEWHERE • Turn the ignition switch to OFF position. • Disconnect the front climate control unit connector (24-pin). • Is there continuity following terminals at harness-side connector. ― Terminal D (rear power MOS FET) and terminal 1R (front climate control unit) ― Terminal C (rear power MOS FET) and terminal 1T (front climate control unit) | Yes | Replace the rear power MOS FET, then go to the next step.
No | Repair or replace for open circuit between the rear power MOS FET and the front climate control unit, then go to Step 13.
12 | INSPECT TO SEE WHETHER MALFUNCTION IS IN REAR POWER MOS FET OR ELSEWHERE • Is the air discharged from rear vent after replace the rear power MOS FET? | Yes | Troubleshooting completed. Explain repairs to customer.
No | Replace the front climate control unit, then go to the next step.
13 | VERIFY REPAIR • Is the air discharged from rear vent? | Yes | Troubleshooting completed. Explain repairs to customer.
No | Recheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.