INSPECTION PROCEDURE 7: A/C outlet air temperature cannot be set


COMMENTS ON TROUBLE SYMPTOM
If the air conditioner outlet temperature cannot be adjusted, the air mixing damper control motor or the heater controller assembly (A/C-ECU) may be faulty.
note It cannot be adjusted while the engine coolant temperature is low.

PROBABLE CAUSES

  • Malfunction of the air mix damper control motor
  • Malfunction of the heater controller assembly (A/C-ECU)

DIAGNOSTIC PROCEDURE

STEP 1. Check the compressor operation
Check that the compressor operates under the following conditions.

  • Engine operation
  • Air volume control dial: Maximum
  • Air conditioner switch: ON
  • Temperature control dial: MAX COOL

Q. Is the check result normal?
Go to Step 2.
Refer to INSPECTION PROCEDURE 6: "The A/C compressor does not work .

STEP 2. M.U.T.-III diagnosis code
Check that the diagnosis code related to the air conditioner is not set.

Q. Is the diagnosis code set?
Carry out the diagnosis code procedures. Refer to .
NO <Single-zone AUTO A/C> : Go to Step 3.
NO <Dual-zone AUTO A/C> : Go to Step 5.

STEP 3. M.U.T.-III actuator test
Carry out the actuator test. (Refer to ).
Item No.17: As air mix damper motor (Select "Damper position setting".)

Q. Is the check result normal?
This diagnosis is complete.
Go to Step 4.

STEP 4. Check of open circuit in IG1, A/DA, A/DA’, A/DB, A/DB’ line between air mixing damper control motor connector and heater controller assembly (A/C-ECU) connector.

Q. Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.

STEP 5. M.U.T.-III actuator test
Carry out the actuator test. (Refer to ).
Item No.16: Dr air mix damper motor (Select "Damper position setting".)

Q. Is the check result normal?
Go to Step 7.
Go to Step 6.

STEP 6. Check of open circuit in IG1, A/DA, A/DA’, A/DB, A/DB’ line between air mixing damper control motor connector (driver’s side) and heater controller assembly (A/C-ECU) connector.

Q. Is the check result normal?
Go to Step 9.
Repair the connector(s) or wiring harness.

STEP 7. M.U.T.-III actuator test
Carry out the actuator test. (Refer to ).
Item No.17: As air mix damper motor (Select "Damper position setting".)

Q. Is the check result normal?
This diagnosis is complete.
Go to Step 8.

STEP 8. Check of open circuit in IG1, A/PA, A/PA’, A/PB, A/PB’ line between air mixing damper control motor connector (passenger’s side) and heater controller assembly (A/C-ECU) connector.

Q. Is the check result normal?
Go to Step 9.
Repair the wiring harness.

STEP 9. Replace the air mixing damper control motor, and recheck the trouble symptom.
Check that A/C outlet air temperature can be adjusted.
note Whenever the motor is replaced, initialise the motor position by using the Actuator Test.

Q. Is the check result normal?
This diagnosis is complete.
Replace the heater controller assembly (A/C-ECU).