INSPECTION
PROCEDURE 1: Cool air does not come
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If cool air does not exit from the air outlets when the blower switch is on with the engine
running, the A/C compressor and the A/C pressure sensor circuits may be defective.
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- The refrigerant quantity is inadequate.
- Damaged harness wires and connectors
- Malfunction of the blower relay
- Malfunction of the blower
- Malfunction of the temperature controller <Cooler>
- Malfunction of the fin thermo sensor
- Malfunction of the A/C switch
- Malfunction of the engine-ECU
- Malfunction of the dual pressure switch
- Malfunction of the A/C compressor relay
- Malfunction of the A/C compressor and clutch
- Malfunction of the heater controller assembly
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STEP 1. Check the M.U.T.-III diagnosis code for engine-ECU.
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Check whether the engine-ECU sets any of the diagnosis codes below:
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P0537: Air thermo sensor circuit low input
P0538: Air thermo sensor circuit high input
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Q.
Is the diagnosis code set?
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YES <4G6> : Carry out the diagnosis code procedures (Refer to GROUP 13A - Code No.
P0537: Air thermo sensor circuit low input  <Cooler> or <A/C>,
Code No. P0538: Air thermo sensor circuit high Input <Cooler>
or <A/C>).
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YES <4D5> : Carry out the diagnosis code procedures (Refer to GROUP 13B - Code No.
P0537: Air thermo sensor circuit low input , Code No. P0538:
Air thermo sensor circuit high Input ).
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YES <4N1> : Carry out the diagnosis code procedures (Refer to GROUP 13C - Code No.
P0537: Air thermo sensor circuit low input , Code No. P0538:
Air thermo sensor circuit high Input ).
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NO <Manual A/C> : Go to Step 2.
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NO <Except manual A/C> : Go to Step 3.
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STEP 2. Check the A/C switch.
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Refer to .
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Q.
Is the A/C switch in good condition?
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 Go to Step 3.
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 Replace the heater controller assembly (Refer to ).
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STEP 3. Check the blower operation.
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Check that air blows through the air outlets.
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(1)Turn the ignition switch to the ON position.
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(2)Air volume adjusting knob: Other than OFF
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(3)Check that the air comes out of the blower.
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Q.
Is the check result normal?
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Go to Step 4.
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Refer to Inspection Procedure 2 "The blower does not work" .
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STEP 4. Check the A/C compressor operation.
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Check that the compressor operates under the following conditions.
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- Engine operation
- Air volume adjusting knob: Maximum air volume
- Temperature adjusting knob: MAX COOL
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Q.
Is the check result normal?
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Go to Step 5.
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Refer to Inspection Procedure 4 "The A/C compressor and clutch assembly
does not work" .
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STEP 5. Refrigerant level check.
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Check that the refrigerant level is adequate (Refer to ).
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Q.
Is the check result normal?
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YES : Go to Step 6.
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Adjust the refrigerant level (Refer to ).
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STEP 6. Check the dual pressure switch.
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Refer to .
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Q.
Is the dual pressure switch in good condition?
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Go to Step 7.
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Replace the dual pressure switch (Refer to ).
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STEP 7. Voltage measurement at dual pressure switch connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the "ON" position.
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(3)Voltage between terminal 1 and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 9.
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Go to Step 8.
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STEP 8. Check of open circuit in dual pressure switch line between
dual pressure switch connector AC/S terminal and engine-ECU connector.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction ).
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Repair or replace the connector(s) or wiring harness.
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STEP 9. Voltage measurement at heater control panel.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Turn the ignition switch to the "ON" position.
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(3)Voltage between terminal 9 and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 11.
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Go to Step 10.
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STEP 10. Check of open circuit in dual pressure switch line heater
control panel connector and dual pressure switch connector and.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction ).
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Repair or replace the connector(s) or wiring harness.
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STEP 11. Retest the system
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent
Malfunction ).
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NO <4G6> : Replace the engine-ECU (Refer to GROUP 13A - Engine-ECU ).
Then go to Step 12.
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NO <4D5> : Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU ).
Then go to Step 12.
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NO <4N1> : Replace the engine-ECU (Refer to GROUP 13C - Engine-ECU ).
Then go to Step 12.
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STEP 12. Retest the system
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Q.
Is the check result normal?
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This diagnosis is complete.
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Replace the heater controller assembly (Refer to ).
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