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INSPECTION PROCEDURE 13: A/C outlet air temperature cannot be set <Vehicles with Single-zone AUTO A/C>
 
 
 
 
TECHNICAL DESCRIPTION (COMMENT)
If the air conditioning outlet temperature cannot be adjusted, the air mixing damper control motor or the A/C controller assembly (A/C-ECU) may be faulty.
noteIt cannot be adjusted while the engine coolant temperature is low.
 
 
 
TROUBLESHOOTING HINT
  • Malfunction of the air mixing damper control motor
  • Malfunction of the A/C compressor assembly
  • Malfunction of the upper case assembly (integrated air mixing damper)
  • Damaged wiring harness or connectors
  • Malfunction of the A/C controller assembly (A/C-ECU)
 
 
 
DIAGNOSIS
STEP 1. Check the compressor operation
Check that the compressor operates under the following conditions.
  • Engine operation
  • Air volume control dial: Maximum
  • Air conditioning switch: ON
  • Temperature control dial: MAX COOL
Is the check result normal?
Go to Step 2.
Refer to inspection procedure "The A/C compressor does not work" .
 
STEP 2. M.U.T.-IIISE actuator test
Carry out the actuator test.
Item No.5: Driver's side air mixing damper position reset
OK: After reset, is the air mixing damper change possible?
Is the check result normal?
This diagnosis is complete.
Go to Step 3.
 
STEP 3. Measure the voltage at the air mixing damper control motor connector.
(1) Disconnect the connector and measure at the wiring harness side.
(2) Voltage between air mixing damper control motor connector IG1 terminal and body ground.
OK: The voltage should measure approximately 12 volts (battery positive voltage)
Is the check result normal?
Go to Step 6.
Go to Step 4.
 
STEP 4. Check of open circuit short to ground, and damage in IG1 line between air mixing damper control motor connector, body ground and A/C controller assembly (A/C-ECU) connector.
Is the check result normal?
Go to Step 5.
Repair or replace the wiring harness or connector(s).
 
STEP 5. Recheck the trouble symptom.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the A/C controller assembly (A/C-ECU).
 
STEP 6. Check of open circuit short to ground, and damage in DA, DB, DA' and DB' line between air mixing damper control motor connector and A/C controller assembly (A/C-ECU) connector.
Is the check result normal?
Go to Step 7.
Repair or replace the wiring harness or connector(s).
 
STEP 7. Check the operation of the air mixing damper.
(1) Remove the air mixing damper control motor.
(2) Insert an hexagonal wrench to the axis of the air mixing damper and turn it by hand to check whether the air mixing damper works normally.
OK: The air mixing damper turns smoothly without tight spots within the range of approximately 80 degrees.
Is the check result normal?
Go to Step 8.
Replace the upper case assembly.
 
STEP 8. Recheck the trouble symptom.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
Replace the air mixing damper control motor. Then go to Step 9.
 
STEP 9. Recheck the trouble symptom.
Is the check result normal?
This diagnosis is complete.
Replace the A/C controller assembly (A/C-ECU).