Mazda CX-9 Grand Touring 2009 Manual page 1748

BLOWER MOTOR OR ELSEWHERE
Measure the voltage at the following blower motor
8*
terminal.
Terminal B (blower motor operation signal)
Is the voltage approx. 12 V?
INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN OR SHORT CIRCUIT
BETWEEN FRONT BLOWER MOTOR AND FRONT
POWER MOS FET) OR ELSEWHERE
9*
Measure the voltage at the following terminal of front
power MOS FET.
Terminal A (blower motor operation signal)
Is voltage approx. 12 V?
INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN OR SHORT CIRCUIT
BETWEEN FRONT POWER MOS FET AND GROUND)
OR ELSEWHERE
10*
Measure the voltage at the following front power MOS
FET terminal.
Terminal E (blower motor operation signal)
Is the voltage approx. 0 V?
INSPECT FRONT A/C UNIT
Inspect the fan for following:.
Is the fan free of interference with the A/C unit
11
case?
Is the fan free of foreign material and
obstruction?
Is the fan normal?
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.
12*
Measure the voltage at the following front power MOS
FET terminal.
Terminal B (blower motor control signal)
Is voltage approx. 10 V?
INSPECT TO SEE WHETHER MALFUNCTION IS IN
WIRING HARNESS (OPEN CIRCUIT BETWEEN
2008 Mazda CX-9 Grand Touring
2008 HVAC Symptom Troubleshooting (HVAC) - Mazda CX-9
Yes Go to the next step.
Inspect the front blower motor,
No
then go to Step 15.
Yes Go to the next step.
Repair the wiring harness
between the front blower
No
motor and front power MOS
FET, then go to Step 15.
Yes Go to the next step.
Repair the wiring harness
between the front power MOS
No
FET and ground, then go to
Step 15.
Yes Go to the next step.
Remove obstruction, repair or
No replace the fan and front A/C
unit case, then go to Step 15.
Replace the front power MOS
Yes
FET, then go to Step 15.
No Go to the next step.
Yes Go to the next step.