Mazda CX-7 2007 Workshop Manual page 1130

STEP
8* INSPECT TO SEE WHETHER MALFUNCTION
IS IN BLOWER MOTOR OR ELSEWHERE
• Measure the voltage at the following blower
motor terminal.
— Terminal A (blower motor operation
signal)
• Is the voltage approx. 12 V?
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 E (blower motor operation
signal)
• Is voltage approx. 12 V?
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?
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?
12* INSPECT TO SEE WHETHER MALFUNCTION
IS IN POWER MOS FET OR ELSEWHERE
• Disconnect power MOS FET connector.
• Turn the airflow volume control dial to 1st
position from OFF.
• Measure the voltage at the following power
MOS FET terminal.
— Terminal B (blower motor control signal)
• Is voltage approx. 10 V?
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— T (blower motor control
signal)
— Terminal E— V (blower motor feedback
signal)
• Is there continuity?
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 A (blower motor control signal)—
ground
• Is there continuity?
15 CONFIRM THAT MALFUNCTION SYMPTOM
DOES NOT RECUR AFTER REPAIR
• Is air discharged from vent?
End Of Sie
07-03–6
SYMPTOM TROUBLESHOOTING
INSPECTION
Yes Go to the next step.
No Inspect the blower motor, then go to Step 15.
Yes Go to the next step.
No Repair the wiring harness between the blower motor and
power MOS FET, then go to Step 15.
Yes Go to the next step.
No Repair the wiring harness between the power MOS FET
and ground, then go to Step 15.
Yes Go to the next step.
No Remove obstruction, repair or replace the fan and A/C unit
case, then go to Step 15.
Yes Replace the power MOS FET, then go to Step 15.
No Go to the next step.
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.
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.
Yes Troubleshooting completed.
Explain repairs to customer.
No Recheck malfunction symptoms, then repeat from Step 1 if
the malfunction recurs.
ACTION