Mazda CX-9 Grand Touring. Manual — part 437

DIAGNOSTIC PROCEDURE

NO.1 INSUFFICIENT AIR (OR NO AIR) BLOWN FROM FRONT VENTS DIAGNOSTIC
PROCEDURE

POSSIBLE CAUSE



Malfunction in front VENT mode system



Malfunction in front HEAT mode system



Malfunction in front DEFROSTER mode system

STEP

INSPECTION

ACTION

1

INSPECT FRONT AIRFLOW MODE
ACTUATOR



Is it okay?

Yes Go to the next step.

No

Repair or replace malfunctioning part

in accordance with inspection result.

2

INSPECT TO SEE WHETHER MALFUNCTION
IS IN FRONT VENT MODE OR OTHER MODES



Does air blow out when in the front VENT
mode?

Yes Go to Step 5.

No

Go to the next step.

3

INSPECT FRONT VENT



Is the front vent clogged?

Yes Remove obstruction, then go to Step 9.

No

Go to the next step.

4

VERIFY THAT DUCT IN DASHBOARD IS
INSTALLED



Is the duct in the dashboard properly installed?

Yes

Inspect the duct for clogging,
deformation and air leakage, then go
to Step 9.

No

Install the duct securely in the proper

position, then go to Step 9.

5

INSPECT TO SEE WHETHER MALFUNCTION
IS IN FRONT HEAT MODE OR FRONT
DEFROSTER MODE



Does air blow out when in the front HEAT
mode?

Yes Go to the next step.

No

Inspect the vent for clogging, then go

to Step 9.

6

INSPECT FRONT DEFROSTER MODE



Does air blow out when in the front
DEFROSTER mode?

Yes

Operation is normal. Recheck
malfunction symptoms.

No

Go to the next step.

7

INSPECT FRONT VENT



Is the vent clogged?

Yes Remove obstruction, then go to Step 9.

No

Go to the next step.

8

VERIFY THAT DEFROSTER DUCT IS
INSTALLED



Is the defroster duct properly installed?

Yes

Inspect the duct for clogging,
deformation, and air leakage, then go
to the next step.

No

Install the duct securely in proper

position, then go to the next step.

2008 Mazda CX-9 Grand Touring

2008 HVAC Symptom Troubleshooting (HVAC) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:14:50 AM

Page 4

© 2005 Mitchell Repair Information Company, LLC.

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

NO.2 AMOUNT OF AIR BLOWN FROM FRONT VENTS DOES NOT CHANGE DESCRIPTION
AND POSSIBLE CAUSE



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

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

9

VERIFY REPAIR



Does air blow out?

Yes

Troubleshooting completed. Explain
repairs to customer.

No

Recheck malfunction symptoms, then

repeat from Step 1 if the malfunction

recurs.

2

Amount of air blown from front vents does not change.

DESCRIPTION



Malfunction in front blower system



Amount of air blown front vents does not change when switching front climate
control unit airflow control dial.

POSSIBLE

CAUSE



Front A/C unit malfunction



Front blower motor malfunction



Malfunction in front power MOS FET system



Front climate control unit malfunction

STEP

INSPECTION

ACTION

1

INSPECT HEATER BLOWER 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.



Turn the fan switch to ON position.



Recirculate air inside the vehicle.



Does the front blower motor operate normal speed?

Yes Go to the next step.

No

Go to Step 4.

Yes

Remove obstruction, then go to

2008 Mazda CX-9 Grand Touring

2008 HVAC Symptom Troubleshooting (HVAC) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:14:50 AM

Page 5

© 2005 Mitchell Repair Information Company, LLC.

3

INSPECT FRONT A/C UNIT INTAKE VENT



Is front A/C unit intake vent clogged?

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
FRONT BLOWER RELAY SYSTEM OR FRONT
POWER MOS FET SYSTEM



Turn the ignition switch to ON position.



Turn the fan switch to OFF position.



Measure the voltage at the following front 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 (OPEN CIRCUIT BETWEEN FUSE
BLOCK AND FRONT BLOWER RELAY) OR
ELSEWHERE



Measure the voltage at the following front blower relay
terminals.



Terminal B (IG2 signal)



Terminal E (B+ signal)



Is the voltage approx. 12 V?

Yes Go to the next step.

No

Repair the wiring harness

between the front blower relay

and A/C 7.5A HEATER 50 A

fuse, then go to Step 15.

6*

INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN CIRCUIT BETWEEN
FRONT BLOWER RELAY AND GROUND) OR
ELSEWHERE



Measure the voltage at the following front 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 front blower relay

and ground, then go to Step 15.

7*

INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN OR SHORT CIRCUIT
BETWEEN FRONT BLOWER RELAY AND FRONT
BLOWER MOTOR) OR BLOWER RELAY



Measure the voltage at the following front blower relay
terminal.



Terminal A (blower motor operation signal)



Is the voltage approx. 12 V?

Yes

Repair the wiring harness
between the front blower relay
and blower motor, then go to
Step 15.

No

Replace the front blower relay,

then go to Step 15.

INSPECT TO SEE WHETHER MALFUNCTION IS IN

2008 Mazda CX-9 Grand Touring

2008 HVAC Symptom Troubleshooting (HVAC) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:14:50 AM

Page 6

© 2005 Mitchell Repair Information Company, LLC.

8*

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 front blower motor,

then go to Step 15.

9*

INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN OR SHORT CIRCUIT
BETWEEN FRONT BLOWER MOTOR AND FRONT
POWER MOS FET) OR ELSEWHERE



Measure the voltage at the following terminal of front
power MOS FET.



Terminal A (blower motor operation signal)



Is voltage approx. 12 V?

Yes Go to the next step.

No

Repair the wiring harness

between the front blower

motor and front power MOS

FET, then go to Step 15.

10*

INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN OR SHORT CIRCUIT
BETWEEN FRONT POWER MOS FET AND GROUND)
OR ELSEWHERE



Measure the voltage at the following front power MOS
FET terminal.



Terminal E (blower motor operation signal)



Is the voltage approx. 0 V?

Yes Go to the next step.

No

Repair the wiring harness

between the front power MOS

FET and ground, then go to

Step 15.

11

INSPECT FRONT A/C UNIT



Inspect the fan for following:.



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 front A/C

unit case, then go to Step 15.

12*

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



Disconnect front power MOS FET connector.



Turn the fun switch to 1st position from off.



Measure the voltage at the following front power MOS
FET terminal.



Terminal B (blower motor control signal)



Is voltage approx. 10 V?

Yes

Replace the front power MOS
FET, then go to Step 15.

No

Go to the next step.

INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN CIRCUIT BETWEEN

Yes Go to the next step.

2008 Mazda CX-9 Grand Touring

2008 HVAC Symptom Troubleshooting (HVAC) - Mazda CX-9

Microsoft

Sunday, November 15, 2009 10:14:50 AM

Page 7

© 2005 Mitchell Repair Information Company, LLC.