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
  • Damaged wiring harness or connectors
  • Malfunction of the heater controller assembly (A/C-ECU)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test.
Carry out the actuator test (Refer to ).
Item No.16: Dr air mixing damper <Single-zone auto A/C, Dual-zone auto A/C>
Item No.17: Ps air mixing damper <Dual-zone auto A/C>

Q. Is the check result normal?
Go to Step 2.
NO <Item No.16 indicates a malfunction> : Go to Step 4.
NO <Item No.17 indicates a malfunction> : Go to Step 6.

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 ).
Go to Step 3.

STEP 3. Check the operation of the heater controller assembly (A/C-ECU).
Check that the temperature set switch can operate.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Refer to inspection procedure 9 "heater control panel assembly (A/C-ECU) power supply system" .

STEP 4. Check of open circuit in air mixing damper control motor line between air mixing damper control motor connector and heater controller assembly (A/C-ECU) connector AM1, AM2, AM4, AM3 and AC+B terminals.

Q. Is the check result normal?
Go to Step 5.
Repair or replace the connector(s) or wiring harness.

STEP 5. Replace the air mix damper control motor (driver’s side) (Refer to ), and recheck the trouble symptom.
Check that the air outlets can be changed.
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) (Refer to ).

STEP 6. Check of open circuit air mixing damper control motor in line between air mixing damper control motor connector and heater controller assembly (A/C-ECU) connector AM1P, AM2P, AM4P, AM3P and AC+B terminals.

Q. Is the check result normal?
Go to Step 7.
Repair or replace the connector(s) or wiring harness.

STEP 7. Replace the air mix damper control motor (front passenger’s side) (Refer to ), and recheck the trouble symptom.
Check that the air outlets can be changed.
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) (Refer to ).