Air Conditioning System (For Automatic Air Conditioning System) Diagnosis System

Air conditioning system data and the Diagnostic Trouble Codes (DTCs) can be read through the Data Link Connector 3 (DLC3) of the vehicle. When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform troubleshooting.

Check the DLC3 (COROLLA_ZRE142 RM000000UZ20CBX.html).

By operating each of the air conditioning control switches as shown in the diagram below, it is possible to enter the diagnostic check mode.

Turn the ignition switch off.

Turn the ignition switch to ON while pressing the A/C control assembly "AUTO" switch and "R/F" switch simultaneously. Hold both switches until the indicator check screen appears.

The indicator check is automatically performed when panel diagnosis is activated. Check that the indicators light up and go off at 1 second intervals 4 times in succession.

HINT:

1. The sensor check automatically starts when the indicator check is completed.
   
2. Press the "OFF" switch to cancel the check mode.
   

Start the engine and warm it up.

Perform the indicator check.

HINT:

After the indicator check is completed, the system enters the DTC check mode automatically.

Read the DTC displayed on the panel.

NOTICE:

1. In the sensor check mode, which is automatically entered after indicator check mode, troubleshooting may be partially performed. Be sure to perform the actuator and sensor checks again.
   
2. If the check is performed in a dark place, DTC 21 may be displayed even though the system is normal.
   

HINT:

Refer to the DTC chart (Diagnostic Trouble Code chart) for details of the codes (Link).

1. When there are no problems, DTC 00 is output.
   
2. As an example, the illustration shows that DTC 21 is output.
   

If the steps are difficult to read because they change automatically, push the "DEF" switch to display the steps one at a time so that they can be read easily. The items are displayed step by step each time the "DEF" switch is pushed.

1. Push the "OFF" switch to finish panel diagnosis.
   
2. Push the "R/F" switch to enter the actuator check mode.
   

Clear the DTC

1. During the sensor check, press the "DEF" switch and "REAR DEF" switch at the same time.
   

Start the engine and warm it up.

Perform the indicator check.

Push the "R/F" switch to perform the actuator check.

HINT:

Be sure to perform the actuator check after starting the engine.

As the actuator check is repeated from steps 1 to 10 at 1 second intervals, check the temperature and air flow visually and by hand.

HINT:

1. The display blinks at 1 second intervals in the step operation.
   
2. As an example, the illustration shows that display code 5 is output.
   
3. Push the "OFF" switch to finish panel diagnosis.
   
4. Push the "AUTO" switch to enter the sensor check mode.
   

If the steps are difficult to read because they change automatically, push the "DEF" switch to display the steps one at a time so that they can be read easily. The items are displayed step by step each time the "DEF" switch is pushed.

HINT:

1. Push the "OFF" switch to finish panel diagnosis.
   
2. Push the "R/F" switch to enter the sensor check mode.