NO.2 AMOUNT OF AIR BLOWN FROM VENTS DOES NOT CHANGE

B3E070301038W04

Full-auto Air Conditioner

2

Amount of air blown from vents does not change.

DESCRIPTION

• Malfunction in blower system

POSSIBLE CAUSE

• A/C unit malfunction (Steps 3, 4, 12)
• Blower motor malfunction (Steps 5-9)
• Malfunction in power MOS FET system (Steps 10, 11, 13, 14)
• Climate control unit malfunction (Step 15)

• 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 HEATER 40 A FUSE

• Inspect the HEATER 40 A fuse.
• Is it normal?
Yes
Go to the next step.
No
Replace the fuse, then go to Step 15. If the fuse burns out immediately, go to the next step.
2

INSPECT TO SEE WHETHER MALFUNCTION IS IN A/C UNIT OR ELSEWHERE

• Turn the ignition switch to the ON position.
• Recirculate air inside the vehicle.
• Does the blower motor rotate smoothly?
Yes
Go to Step 4.
No
Go to the next step.
3

INSPECT A/C UNIT INTAKE VENT

• Is A/C unit intake vent clogged?
Yes
Remove obstruction, then go to Step 15.
No
Inspect if there are any obstruction in the A/C unit passage, then go to Step 15.
4*

INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER RELAY SYSTEM OR POWER MOS FET SYSTEM

• Turn the ignition switch to ON position.
• Measure the voltage at the following blower motor terminal.
- Terminal B (blower motor operation signal)
• Is voltage approx. 12 V?
Yes
Go to Step 8.
No
Go to the next step.
5*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN FUSE BLOCK AND BLOWER RELAY) OR ELSEWHERE

• Measure the voltage at the following blower relay terminals.
- Terminal B (IG2 signal)
- Terminal A (B+ signal)
• Is the voltage approx. 12 V?
Yes
Go to the next step.
No
Repair the wiring harness between the blower relay and HEATER 40 A fuse, then go to Step 15.
6*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER RELAY AND GROUND) OR ELSEWHERE

• Measure the voltage at the following blower relay terminal.
- Terminal D (GND signal)
• Is the voltage approx. 0 V?
Yes
Go to the next step.
No
Repair the wiring harness between the blower relay and ground, then go to Step 15.
7*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER RELAY AND BLOWER MOTOR) OR BLOWER RELAY

• Measure the voltage at the following blower relay terminal.
- Terminal E (blower motor operation signal)
• Is the voltage approx. 12 V?
Yes
Repair the wiring harness between the blower relay and blower motor, then go to Step 15.
No
Replace the blower relay, then go to Step 15.
8*

INSPECT TO SEE WHETHER MALFUNCTION IS IN BLOWER MOTOR OR ELSEWHERE

• Measure the voltage at the following blower motor terminal.
- Terminal B (blower motor operation signal)
• Is the voltage approx. 12 V?
Yes
Go to the next step.
No
Inspect the blower motor, then go to Step 15.
9*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN BLOWER MOTOR AND POWER MOS FET) OR ELSEWHERE

• Measure the voltage at the following terminal of power MOS FET.
- Terminal B (blower motor operation signal)
• Is voltage approx. 12 V?
Yes
Go to the next step.
No
Repair the wiring harness between the blower motor and power MOS FET, then 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 power MOS FET terminal.
- Terminal A (blower motor operation signal)
• Is the voltage approx. 0 V?
Yes
Go to the next step.
No
Repair the wiring harness between the power MOS FET and ground, then go to Step 15.
11

INSPECT A/C UNIT

• Inspect the fan in A/C unit.
- Is the fan free of interference with the A/C unit case?
- Is the fan free of foreign material and obstruction?
• Is the fan normal?
Yes
Go to the next step.
No
Remove obstruction, repair or replace the fan and A/C unit case, then go to Step 15.
12*

INSPECT TO SEE WHETHER MALFUNCTION IS IN POWER MOS FET OR ELSEWHERE

• Disconnect power MOS FET connector.
• Measure the voltage at the following power MOS FET terminal.
- Terminal B (blower motor control signal)
• Is voltage approx. 10 V?
Yes
Replace the power MOS FET, then go to Step 15.
No
Go to the next step.
13*

INSPECT TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER MOS FET AND CLIMATE CONTROL UNIT) OR ELSEWHERE

• Turn the ignition switch to the LOCK position.
• Disconnect climate control unit connector.
• Inspect for continuity at the following terminals between the power MOS FET and climate control unit.
- Terminal B-F (blower motor control signal)
- Terminal C-D (blower motor feedback signal)
• Is there continuity?
Yes
Go to the next step.
No
Repair the wiring harness between the power MOS FET and climate control unit, then go to Step 15.
14*

INSPECT TO SEE WHETHER MALFUNCTION IS IN CLIMATE CONTROL UNIT OR WIRING HARNESS (SHORT TO GROUND IN WIRING HARNESS BETWEEN POWER MOS FET AND CLIMATE CONTROL UNIT)

• Inspect for continuity at the following terminal between the power MOS FET and ground.
- Terminal B (blower motor control signal)-ground
• Is there continuity?
Yes
Repair the wiring harness between the power MOS FET and ground, then go to the next step.
No
Replace the climate control unit, then go to the next step.
15

CONFIRM 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.