AMOUNT OF AIR BLOWN FROM REAR VENTS DOES NOT CHANGE [FULL-AUTO AIR CONDITIONER]

DESCRIPTION

• Rear blower motor does not operate even if airflow volume control switch is operated (no airflow from vent)

• Rear blower motor operation does not change even if airflow volume control switch is operated (airflow volume from vent does not change)

POSSIBLE CAUSE

• R.HEATER 20 A fuse malfunction

• Rear blower relay malfunction

• Rear A/C unit malfunction

― Clogging

― Interference between blower motor fan and case

• Rear blower motor malfunction

• Power MOS FET malfunction

• Front body control module (FBCM) malfunction

• Rear climate control unit malfunction

• Open circuit or short to ground or short to power supply in wiring harness between the following terminals:

― Rear blower motor terminal A — Power MOS FET terminal B

― Power MOS FET terminal C — Rear climate control unit terminal H

― Power MOS FET terminal D — Rear climate control unit terminal F

• Open circuit or short to power supply in wiring harness between the following terminals:

― Power MOS FET terminal A — body ground

― Rear blower relay terminal A — Front body control module (FBCM) terminal 2Z

• Open circuit or short to ground in wiring harness between the following terminals:

― Rear blower relay terminal C — R.HEATER 20 A fuse

― Rear blower relay terminal E — R.HEATER 20 A fuse

― Rear blower relay terminal D — rear blower motor terminal B

• 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.

Step	Inspection		Action
1	VERIFY REAR BLOWER MOTOR OPERATION • Switch the ignition ON (engine off or on). • Set the airflow volume control dial to 1 or more. • Set the air intake mode to REC. • Does the rear blower motor in the rear A/C unit rotate smoothly?	Yes	Go to the next step.
1		No	Go to Step 3.
2	INSPECT REAR A/C UNIT FOR CLOGGING • Is there clogging in the vent of the rear A/C unit?	Yes	Remove the obstruction, then go to Step 15.
2		No	Verify that there is no obstruction in the air duct between the front A/C unit and the rear A/C unit, there is no air filter clogging, and the evaporator is not frosted (frozen), then go to Step 15.
3^*	INSPECT VOLTAGE AT REAR BLOWER MOTOR TERMINAL • Switch the ignition ON (engine off or on). • Set the airflow volume control dial to 5 or more. • Measure the voltage at the following terminals (wiring harness-side): ― Rear blower motor terminal B • Is voltage B+?	Yes	Go to Step 9.
3^*		No	Go to the next step.
4	INSPECT FUSE • Inspect R.HEATER 20 A fuse • Is the fuse normal?	Yes	Go to the next step.
4		No	If the fuse is blown: • Refer to the wiring diagram and verify whether or not there is a common connector between R.HEATER 20 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. Go to Step 15.
5^*	INSPECT VOLTAGE AT REAR BLOWER RELAY TERMINAL • Measure the voltage at the following terminal. ― Rear blower relay terminal C ― Rear blower relay terminal E • Is voltage B+?	Yes	Go to the next step.
5^*		No	Refer to the wiring diagram and verify whether or not there is a common connector between R.HEATER 20 A fuse terminal and 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 open circuit. Go to Step 15.
6^*	INSPECT VOLTAGE AT REAR BLOWER RELAY TERMINAL • Measure the voltage at the following terminal. ― Rear blower relay terminal A • Is the voltage approx. 0 V?	Yes	Go to Step 8.
6^*		No	Go to the next step.
7^*	INSPECT VOLTAGE AT FRONT BODY CONTROL MODULE (FBCM) TERMINAL • Measure the voltage at the following terminal. ― Front body control module (FBCM) terminal 2Z • Is the voltage approx. 0 V?	Yes	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 for a open circuit or short to power supply. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has a open circuit or short to power supply. Go to Step 15.
7^*		No	Replace the front body control module (FBCM). (See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION.) Go to Step 15.
8^*	INSPECT VOLTAGE AT REAR BLOWER RELAY TERMINAL • Measure the voltage at the following terminal. ― Rear blower relay terminal D • Is voltage B+?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between rear blower relay terminal and rear blower motor 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 open circuit. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has a open circuit. Go to Step 15.
8^*		No	Replace the rear blower relay, then go to Step 15. (See RELAY LOCATION.)
9	INSPECT REAR BLOWER MOTOR. • Inspect the rear blower motor. (See REAR BLOWER MOTOR INSPECTION.) • Is the rear blower motor normal?	Yes	Go to the next step.
9		No	Replace the rear blower motor, then go to Step 15. (See REAR BLOWER MOTOR REMOVAL/INSTALLATION.)
10	INSPECT POWER MOS FET • Inspect the power MOS FET. (See POWER METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR (POWER MOS FET) INSPECTION.) • Is the power MOS FET normal?	Yes	Go to the next step.
10		No	Replace the power MOS FET, then go to Step 15. (See POWER METAL OXIDE SEMICONDUCTOR FIELD EFFECT TRANSISTOR (POWER MOS FET) REMOVAL/INSTALLATION.)
11	VERIFY THAT THERE IS NO OBSTRUCTION IN REAR BLOWER MOTOR FAN ROTATION • Inspect the rear blower motor fan in the rear A/C unit. ― Is the fan free of interference with the blower unit case? ― Is the fan free of foreign matter and obstructions? • Is the fan normal?	Yes	Go to the next step.
11		No	Remove the obstruction or repair/replace the rear blower motor fan, rear A/C unit, then go to Step 15. (See REAR A/C UNIT REMOVAL/INSTALLATION.) (See REAR A/C UNIT DISASSEMBLY/ASSEMBLY.)
12^*	INSPECT POWER MOS FET CIRCUIT FOR SHORT TO GROUND • Switch the ignition off. • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Disconnect the power MOS FET connector and rear climate control unit connector. • Inspect for continuity between the body ground and following terminals (wiring harness-side): ― Power MOS FET terminal B ― 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 the following terminals: • Power MOS FET — rear climate control unit • Power MOS FET — rear blower motor 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 Step 15.
12^*		No	Go to the next step.
13^*	INSPECT POWER MOS FET CIRCUIT FOR OPEN CIRCUIT • Power MOS FET and rear climate control unit connectors are disconnected. • Inspect for continuity between the following terminals (wiring harness-side): ― Power MOS FET terminal A — GND ― Power MOS FET terminal B — rear blower motor terminal A ― 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.
13^*		No	Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: • Power MOS FET — GND • Power MOS FET — rear blower motor • Power MOS FET — 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 open circuit. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has an open circuit. Go to Step 15.
14^*	INSPECT POWER MOS FET CIRCUIT FOR SHORT TO POWER SUPPLY • Verify that Power MOS FET connector and rear climate control unit connector is disconnected. • Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION.) • Switch the ignition ON (engine off or on). • Measure the voltage at the following terminal (wiring harness side). ― Power MOS FET terminal A ― Power MOS FET terminal B ― Power MOS FET terminal C ― Power MOS FET terminal D • Is the voltage approx. 0 V?	Yes	Replace the rear climate control unit, go to the next step. (See REAR CLIMATE CONTROL UNIT REMOVAL/INSTALLATION.)
14^*		No	Refer to the wiring diagram and verify whether or not there is a common connector between the following terminals: • Power MOS FET — GND • Power MOS FET — rear blower motor • Power MOS FET — 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 power supply. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has a short to power supply. Go to the next step.
15	VERIFY THAT MALFUNCTION SYMPTOM DOES NOT RECUR AFTER REPAIR • Is air discharged from vent?	Yes	Troubleshooting completed. Explain repairs to customer.
15		No	Recheck malfunction symptoms, then repeat from Step 1 if the malfunction recurs.