Page 824 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-123
STEP 2. Measure the voltage at A/C-ECU connector C-16.
(1) Disconnect A/C-ECU connector C-16 and measure the
voltage at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 28 and ground.
The measured value should be approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approx. 12 volts?
YES : Go to Step 4.
NO : Go to Step 3.
STEP 3. Check the wiring harness between A/C-ECU
connector C-16 (terminal 28) and the ignition switch (IG2).
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AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-124
NOTE: Also check junction block connectors C-211 and C-215
for loose, corroded, or damaged terminals, or terminals pushed
back in the connector. If junction block connector C-211 or
C-215 is damaged, repair or replace the connector as
described in GROUP 00E, Harness Connector Inspection
P.00E-2.
Q: Is the wiring harness between A/C-ECU connector C-16
(terminal 28) and the ignition switch (IG2) in good
condition?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
STEP 4. Measure the voltage at A/C-ECU connector C-16.
(1) Disconnect A/C-ECU connector C-16 and measure the
voltage at the harness side.
(2) Turn the ignition switch to the "ACC" position.
(3) Measure the voltage between terminal 36 and ground.
The measured value should be approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approx. 12 volts?
YES : Go to Step 6.
NO : Go to Step 5.
Page 826 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-125
STEP 5. Check the wiring harness between A/C-ECU
connector C-16 (terminal 36) and the ignition switch (ACC).
NOTE: Also check intermediate connector C-29 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-29 is damaged, repair or
replace the connector as described in GROUP 00E, Harness
Connector Inspection P.00E-2.
Q: Is the wiring harness between A/C-ECU connector C-16
(terminal 36) and the ignition switch (ACC) in good
condition?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
Page 827 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-126
STEP 6. Measure the voltage at A/C-ECU connector C-15.
(1) Disconnect A/C-ECU connector C-16 and measure the
voltage at the harness side.
(2) Measure the voltage between terminal 3 and ground.
The measured value should be approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approx. 12 volts?
YES : Go to Step 8.
NO : Go to Step 7.
STEP 7. Check the wiring harness between A/C-ECU
connector C-15 (terminal 3) and the battery.
Page 828 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-127
NOTE: Also check intermediate connector C-29 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-29 is damaged, repair or
replace the connector as described in GROUP 00E, Harness
Connector Inspection P.00E-2.
Q: Is the wiring harness between A/C-ECU connector C-16
(terminal 3) and the battery in good condition?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
STEP 8. Measure the resistance at A/C-ECU connector
C-16.
(1) Disconnect A/C-ECU connector C-16, and measure at the
wiring harness side.
(2) Measure the resistance between terminal 27 and ground.
The measured value should be 2 ohms or less.
Q: Does the measured resistance value correspond with
this range?
YES : Replace the A/C-ECU, and check that the air
conditioning works normally.
NO : Go to Step 9.
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AUTO A/C DIAGNOSIS
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STEP 9. Check the wiring harness between A/C-ECU
connector C-16 (terminal 27) and the ground.
Q: Is the wiring harness between A/C-ECU connector C-16
(terminal 27) and ground in good condition?
YES : It can be assumed that this malfunction is intermittent.
Refer to GROUP 00, How to Use
Troubleshooting/Inspection Service Points
How to
Cope with Intermittent Malfunctions P.00-14. check
that the air conditioning works normally.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
INSPECTION PROCEDURE 12: When Sunlight Intensity Changes, Air Outlet Temperature Does Not
Change.
.
CIRCUIT OPERATION
When the blower air temperature cannot be changed
even if the preset temperature is changed, the sen-
sors may be defective.
.
TROUBLESHOOTING HINTS
Improper amount of refrigerant
Malfunction of the A/C pressure sensor
Malfunction of the photo sensor
Malfunction of the A/C-ECU
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector.
Refer to component locations GROUP-70
Refer to configuration diagrams GROUP-80
Refer to circuit diagrams GROUP-90
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AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-132
STEP 5. Check the wiring harness between photo sensor
connector C-04 (terminals 3, 4) and A/C-ECU connector
C-15 (terminal 19), C-16 (terminal 25).
Q: Is the wiring harness between photo sensor connector
C-04 (terminals 3, 4) and A/C-ECU connector C-15
(terminal 19), C-16 (terminal 25) in good condition?
YES : Go to Step 6.
NO : Repair the wiring harness. Check that the air
conditioning works normally.
STEP 6. Replace the photo sensor.
Q: Does the A/C operate normally?
YES : No action is necessary and testing is complete.
NO : Replace the A/C-ECU. Check that the air conditioning
works normally.
STEP 7. Check the refrigerant level.
Use the refrigerant recovery station to remove all of the refrig-
erant, and then calculate the amount of the refrigerant and
charge it.
Q: Is the refrigerant level correct?
YES : Refer to GROUP 55A, Symptom Chart P.55-68.
NO : Correct the refrigerant level. Check that the air
conditioning works normally. (Refer to GROUP 55A
On-vehicle Service P.55-141).
Page 853 of 1500