Mazda CX-7 2007 Workshop Manual page 1129

NO.2 AMOUNT OF AIR BLOWN FROM VENTS DOES NOT CHANGE
End Of Sie
Full-auto Air Conditioner
2 Amount of air blown from vents does not change.
• Malfunction in blower system
DESCRIPTION
• A/C unit malfunction
• Blower motor malfunction
POSSIBLE
• Malfunction in power MOS FET system
CAUSE
• Climate control unit malfunction
• 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.
Diagnostic procedure
STEP
1 INSPECT HEATER BLOWER 40 A FUSE
• Inspect the HEATER BLOWER 40 A fuse.
• Is it normal?
2 INSPECT TO SEE WHETHER MALFUNCTION
IS IN A/C UNIT OR ELSEWHERE
• Turn the ignition switch to the ON position.
• Turn the airflow volume control dial to ON
position.
• Recirculate air inside the vehicle.
• Does the blower motor rotate smoothly?
3 INSPECT A/C UNIT INTAKE VENT
• Is A/C unit intake vent clogged?
4* INSPECT TO SEE WHETHER MALFUNCTION
IS IN BLOWER RELAY SYSTEM OR POWER
MOS FET SYSTEM
• Turn the ignition switch to ON position.
• Turn the airflow volume control dial to OFF
position.
• Measure the voltage at the following blower
motor terminal.
— Terminal A (blower motor operation
signal)
• Is voltage approx. 12 V?
5* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN FUSE BLOCK AND
BLOWER RELAY) OR ELSEWHERE
• Measure the voltage at the following blower
relay terminals.
— Terminal B (IG2 signal)
— Terminal A (B+ signal)
• Is the voltage approx. 12 V?
6* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN BLOWER RELAY
AND GROUND) OR ELSEWHERE
• Measure the voltage at the following blower
relay terminal.
— Terminal D (GND signal)
• Is the voltage approx. 0 V?
7* INSPECT TO SEE WHETHER MALFUNCTION
IS IN WIRING HARNESS (LACK OF
CONTINUITY BETWEEN BLOWER RELAY
AND BLOWER MOTOR) OR BLOWER RELAY
• Measure the voltage at the following blower
relay terminal.
— Terminal C (blower motor operation
signal)
• Is the voltage approx. 12 V?
SYMPTOM TROUBLESHOOTING
INSPECTION
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.
Yes Go to Step 4.
No Go to the next step.
Yes Remove obstruction, then go to Step 15.
No Inspect if there are any obstruction in the A/C unit passage,
then go to Step 15.
Yes Go to Step 8.
No Go to the next step.
Yes Go to the next step.
No Repair the wiring harness between the blower relay and
HEATER BLOWER 40 A fuse, then go to Step 15.
Yes Go to the next step.
No Repair the wiring harness between the blower relay and
ground, then go to Step 15.
Yes Repair the wiring harness between the blower relay and
blower motor, then go to Step 15.
No Replace the blower relay, then go to Step 15.
id070300800500
ACTION
07-03–5
07-03