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


BHE070301038W04

Full-auto Air Conditioner

2

Amount of air blown from vents does not change.

DESCRIPTION

• Malfunction in blower system.

POSSIBLE CAUSE

• Blower motor malfunction (Steps 3, 4, 12)
• Blower unit malfunction (Steps 5-9)
• Power transistor system malfunction (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, check to make sure connectors, terminals and wiring harnesses are connected correctly and undamaged.

Diagnostic procedure

STEP

INSPECTION

ACTION

1

INSPECT A/C 7.5 A FUSE

• Inspect A/C 7.5 A fuse.
• Is it normal?
Yes
Go to next step.
No
Replace fuse, then go to Step 15. If fuse burns out immediately, go to next step.
2

CHECK TO SEE WHETHER MALFUNCTION IS IN BLOWER UNIT OR ELSEWHERE

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

INSPECT BLOWER UNIT INTAKE VENT

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

CHECK TO SEE WHETHER MALFUNCTION IS IN BLOWER RELAY SYSTEM OR POWER TRANSISTOR SYSTEM

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

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

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

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

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

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

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

CHECK TO SEE WHETHER MALFUNCTION IS IN BLOWER MOTOR OR ELSEWHERE

• Test voltage at the following terminal of blower motor.
– Terminal A (blower motor operation signal)
• Is voltage approx. 12 V?
Yes
Go to next step.
No
Inspect blower motor, then go to Step 15. (See BLOWER MOTOR INSPECTION.)
9*

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

• Test voltage at the following terminal of power transistor.
– Terminal B (blower motor operation signal)
• Is voltage approx. 12 V?
Yes
Go to next step.
No
Repair wiring harness between blower motor and power transistor, then go to Step 15.
10*

CHECK TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER TRANSISTOR AND GROUND) OR ELSEWHERE

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

INSPECT BLOWER UNIT

• Inspect fan in blower unit.
– Is fan free of interference with blower unit case?
– Is fan free of foreign material and obstruction?
• Is voltage approx. 0 V?
Yes
Go to next step.
No
Remove obstruction, repair or replace fan and blower unit case, then go to Step 15.
12*

CHECK TO SEE WHETHER MALFUNCTION IS IN POWER TRANSISTOR OR ELSEWHERE

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

CHECK TO SEE WHETHER MALFUNCTION IS IN WIRING HARNESS (LACK OF CONTINUITY BETWEEN POWER TRANSISTOR AND A/C AMPLIFIER) OR ELSEWHERE

• Turn ignition switch to LOCK position.
• Disconnect A/C amplifier connector.
• Inspect for continuity at the following terminals between power transistor and A/C amplifier.
– Terminal D-1A (24-pin, blower motor control signal)
– Terminal C-1B (24-pin, blower motor feedback signal)
• Is there continuity?
Yes
Go to next step.
No
Repair wiring harness between power transistor and A/C amplifier, then go to Step 15.
14*

CHECK TO SEE WHETHER MALFUNCTION IS IN A/C AMPLIFIER OR WIRING HARNESS (SHORT TO GROUND BETWEEN POWER TRANSISTOR AND A/C AMPLIFIER) OR ELSEWHERE

• Inspect for continuity at the following terminal between power transistor and ground.
– Terminal A (24-pin, blower motor control signal)-ground
• Is there continuity?
Yes
Repair wiring harness between power transistor and ground, then go to next step.
No
Replace A/C amplifier, then go to next step.
15

VERIFY THAT MALFUNCTION SYMPTOM OCCURS AFTER REPAIR

• Is air discharged from vent?
Yes
Troubleshooting completed.
Explain repairs to customer.
No
Recheck malfunction symptoms, then repeat from Step 1 if malfunction recurs.