Section 477 (Air Conditioning System - Diagnosis): Pre-Check

If compressor lock occurs during A/C operation, the A/C switch indicator on the A/C control assembly starts blinking.

When this occurs, check for compressor lock (DTC 1422/22) using diagnosis trouble code check, and then proceed to inspect the circuit or the component.

Compressor lock sensor circuit. --> (See DTC B1422/22 COMPRESSOR LOCK SENSOR CIRCUIT )

Fig 1: A/C Compressor Lock Blinking Pattern

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By operating each of the A/C control switches as shown in the diagram below, it is possible to enter the diagnosis check mode.

Fig 2: List Of Operation Methods

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1. Turn the ignition switch to ON while pressing the A/C control AUTO switch and R/F switch simultaneously.
   Fig 3: Identifying Indicator Check (w/o Lexus Navigation System)

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   Fig 4: Identifying Indicator Check (w/Lexus Navigation System)

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2. Check that all indicators light up and go off at 1 second intervals of 4 times in succession.
3. Check that the buzzer sounds when the indicators light up.

   HINT:

   • After the indicator check ends, the diagnostic trouble code check begins automatically.
   • Press the OFF switch when cancelling the check mode.
     Fig 5: Identifying Blinking Pattern

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1. Perform an indicator check. After the indicator check is completed, the system enters the DTC check mode automatically.
2. Read the code displayed on the panel. Refer to the list of codes in DIAGNOSTIC TROUBLE CODE CHART  when reading the trouble codes. (Trouble codes are output at the driver side temperature display.)

   If the slower display is desired, press the driver side UP switch and change it to step operation. Every time the UP switch is pressed, the display changes by 1 step.

   Fig 6: Identifying DTC Check (w/o Lexus Navigation System)

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   Fig 7: Identifying DTC Check (w/ Lexus Navigation System)

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   HINT:

   • If the buzzer sounds when a trouble code is being read, it means the trouble indicated by that trouble code continues to occur.
   • If the buzzer does not sound when a trouble code is being read, it means the trouble indicated by that trouble code occurred earlier (such as poor connector contacts, etc.).
     Fig 8: Identifying DTC Check (w/o Lexus Navigation System)

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     Fig 9: Identifying DTC Check (w/ Lexus Navigation System)

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1. Hook up the LEXUS hand-held tester to the DLC3.
2. Read the DTC following the prompts on the tester screen. Please refer to the LEXUS hand-held tester operator's manual for further details.
   Fig 10: Checking Using Lexus Hand-Held Tester

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Clear DTC memory by one of the following operations:

1. During sensor check, press the "Rr DEF" switch while pressing the "Front DEF" switch.
   Fig 11: Clearing DTC (w/o Lexus Navigation System)

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   Fig 12: Clearing DTC (w/ Lexus Navigation System)

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2. Pull out the A/C fuse in the driver side J/B for 30 seconds, or longer to clear the DTC memory.
3. After reinserting the fuse, check that the normal code is output.
   Fig 13: Pulling Out A/C Fuse In Driver Side J/B

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Step motor initializing procedure (Automatic initializing).

1. The battery is connected and ignition switch is turned to ON for the first time, the initializing function of the step motors is activated. In this case, the "FRONT DEF" indicator blinks.
   Fig 14: Identifying Step Motor Initializing Procedure (w/o Lexus Navigation System)

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   Fig 15: Identifying Step Motor Initializing Procedure (w/ Lexus Navigation System)

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2. If mode indication is different from the actual air outlet in actuator check, turn the ignition switch to ON or START while pressing "Rr DEF" and "OFF" switches simultaneously. Step motor initialization occurs and the "DEF" indicator blinks.
   Fig 16: Rear Def Indicator Switch (1 Of 2)

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   Fig 17: Rear Def Indicator Switch (2 Of 2)

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If the step motor is continuously operating for many hours, the step motor is forced to stop and the "AUTO" indicator blinks. In this case, the step motor automatically restores after cooling for approx. 7 minutes.

Fig 18: Locating Auto Indicator Blinks (Without Navigation System)

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Fig 19: Locating Auto Indicator Blinks (With Navigation System)

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1. After entering the sensor check mode, press the R/F switch.
2. Since each damper, motor and relay automatically operates at 1 sec. intervals beginning in order from 0 in the temperature display, check the temperature and air flow visually and by hand.

   If the slower display is desired, press the driver UP switch and change it to step operation. Each time the driver UP switch is pressed, the display changes by 1 step.

   Fig 20: Identifying R/F Switch (Without Navigation System)

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   Fig 21: Identifying R/F Switch (With Navigation System)

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   HINT:

   • The buzzer sounds when the display trouble code changes.
   • Code are displayed in order from the smaller to the larger numbers.
   • To cancel the check mode, press the OFF switch.
     Fig 22: Identifying Up Switch (Without Navigation System)

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   Fig 23: Identifying Up Switch (With Navigation System)

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   Fig 24: Identifying Blower Condition Chart

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The vehicle's ECM uses the ISO 9141-2 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

Fig 25: Identifying Dlc3 Terminal Connector

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HINT:

According to the DATA LIST displayed by LEXUS hand-held tester, you can read the value of the switch, sensor, actuator and so on without parts removal. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time.

1. Connect the LEXUS hand-held tester to the DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, read the "DATA LIST".
   ITEM SPECIFICATION
   
   

   Item	Measurement Item/ Display (Range)	Normal Condition	Diagnostic Note
   A/C SIG	A/C SW Status/ ON or OFF	A/C SW Push: ON A/C SW Release: OFF	<--
   A/C MAG CLUTCH	A/C magnet clutch status/ ON or OFF	A/C SW Push: ON A/C SW Release: OFF	<--

HINT:

Performing the ACTIVE TEST using LEXUS hand-held tester allows the relay, VSV, actuator and so on to operate without parts removal. Performing the ACTIVE TEST as a first step of troubleshooting is one of the method to shorten the labor time.

It is possible to display the DATA LIST during the ACTIVE TEST.

1. Connect the LEXUS hand-held tester to the DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, read the "ACTIVE TEST".
   DIAGNOSTIC ITEM TEST
   
   

   Item	Test Details	Diagnostic Note
   A/C MAG CLUTCH	Control the A/C magnet clutch ON/OFF	-