02 diagnostics of hvac system08 diagnostic procedure for sensors_h

1、DIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)8. Diagnostic Procedure for SensorsA: AMBIENT SENSORTROUBLE SYMPTOM:Fan speed is not switched when the fan speed control dial is in AUTO position.WIRING DIAGRAM:AMBIENT SENSORF78F45B: B283F45F78AC-00750AC-251345678910111213141516171

2、8192021222324113578910111213141516171819202145B62B17B9A: B282 B: B283AUTO A/C CONTROL MODULEDIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)AC-26StepCheckYesNo1CHECK AMBIENT SENSOR.1) Turn the ignition switch to OFF. 2)Disconnect the connector from ambient sen- sor.3)Measure the

3、resistance between connector terminals of ambient sensor.TerminalsNo. 1 No. 2:Is the resistance approx. 2.2 kW at 25C (77F)?Go to step 2.Replace the ambi- ent sensor.2CHECK INPUT SIGNALS FOR AMBIENT SENSOR.1) Turn the ignition ON.2) Measure the voltage between (F78) connec- tor terminals.Connector &

4、 terminal(F78) No. 1 (+) No. 2 (-):Is the voltage approx. 5 V?Go to step 6.Go to step 3.3CHECK OUTPUT SIGNALS FROM A/C CON- TROL MODULE.1) Turn the ignition switch to OFF. 2)Pull out the A/C control unit.3) Disconnect the connector from ambient sen- sor.4) Turn the ignition switch to ON.5) Measure t

5、he voltage between connector ter- minals of A/C control module.Connector & terminal(B283) No. 9 (+) No. 17 (-):Is the voltage approx. 5 V?Go to step 4.Go to step 6.4CHECK HARNESS CONNECTOR BETWEEN A/C CONTROL MODULE AND AMBIENT SENSOR.1) Turn the ignition switch to OFF. 2)Disconnect the connectors f

6、rom A/C control module.3)Measure the resistance of harness between A/C control module and ambient sensor.Connector & terminal(F78) No. 1 (B283) No. 9:Is the resistance less than 1W?Go to step 5.Repair the open circuit in harness between A/C con- trol module and ambient sensor.5CHECK HARNESS CONNECTO

7、R BETWEEN A/C CONTROL MODULE AND AMBIENT SENSOR.Measure the resistance of harness between A/C control module and ambient sensor.Connector & terminal(F78) No. 2 (B283) No. 17:Is the resistance less than 1W?Go to step 6.Repair the open circuit in harness between A/C con- trol module and ambient sensor

8、.6CHECK POOR CONTACT.Check poor contact in A/C control module con- nector.Is there poor contact in con- nector?Repair the con- nector.Replace the A/C control module.DIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)B: IN-VEHICLE SENSORTROUBLE SYMPTOM: When turning the AUTO switch t

9、o ON, blower fan speed, outlet port and inlet port is not changed. If the switch LED indicates that the sensor is malfunctioning, replace the A/C control module. The in-vehi- cle sensor is built into the A/C control module and cannot be replaced as a single unit.C: EVAPORATOR SENSORWIRING DIAGRAM:B2

10、56B: B283AC-00679AC-271135791011121314151617181920EVAPORATION THERMO SWITCH21B256B7B17A: B282 B: B283AUTO A/CCONTROL MODULEDIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)AC-28StepCheckYesNo1CHECK EVAPORATOR SENSOR. 1)Turn the ignition switch to OFF. 2)Remove the glove box.3) Dis

11、connect the connector from evaporator sensor.4) Measure the resistance between connector terminals of evaporator sensor.TerminalsNo. 1 No. 2:Is the resistance approx. 3.3 kW at 20C (68F)?Go to step 2.Replace the evap- orator sensor.2CHECK INPUT SIGNALS FOR EVAPORA- TOR SENSOR.1) Turn the ignition sw

12、itch to ON.2) Measure the voltage between (B256) con- nector terminal and chassis ground.Connector & terminal(B256) No. 2 (+) Chassis ground (-):Is the voltage approx. 5 V?Go to step 6.Go to step 3.3CHECK OUTPUT SIGNALS FROM A/C CON- TROL MODULE.1) Turn the ignition switch to OFF. 2)Pull out the A/C

13、 control module. 3)Turn the ignition switch to ON.4)Measure the voltage between A/C control module connector terminals.Connector & terminal(B283) No. 7 (+) No. 17 (-):Is the voltage approx. 5 V?Go to step 4.Go to step 6.4CHECK HARNESS CONNECTOR BETWEEN A/C CONTROL MODULE AND EVAPORA- TOR SENSOR.1) T

14、urn the ignition switch to OFF. 2)Disconnect the connectors from A/C control module.3)Measure the resistance of harness between A/C control module and evaporator sensor.Connector & terminal(B256) No. 2 (B283) No. 7:Is the resistance less than 1W?Go to step 5.Repair the open circuit in harness betwee

15、n A/C con- trol module and evaporator sensor.5CHECK HARNESS CONNECTOR BETWEEN A/C CONTROL MODULE AND EVAPORA- TOR SENSOR.Measure the resistance of harness between A/C control module and evaporator sensor.Connector & terminal(B256) No. 1 (B283) No. 17:Is the resistance less than 1W?Go to step 6.Repai

16、r the open circuit in harness between A/C con- trol module and evaporator sensor.6CHECK POOR CONTACT.Check poor contact in A/C control module con- nector.Is there poor contact in con- nector?Repair the con- nector.Replace the A/C control module.DIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C)

17、(DIAGNOSTICS)D: SUNLOAD SENSORTROUBLE SYMPTOM: Sensor identified that sunlight is at maximum. Then, A/C system is controlled to COOL side. Sensor identified that sunlight is at minimum. Then, A/C system is controlled to HOT side.NOTE:When the sunload sensor is checked indoors or in the shade, open c

18、ircuit might be indicated. Always check the sunload sensor at a place where sun shines directly on it.WIRING DIAGRAM:i51SUNLOAD SENSORi1i2B36B37AUTO A/C CONTROL MODULEA: B282 B: B283i51A:B282B:B283i1i2AC-00751AC-29B17231B167213457891011121314151617181920212223241345678910 1121314151617181920212223 2

19、121357910111213141516171819201357910111213141516DIAGNOSTIC PROCEDURE FOR SENSORSHVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)AC-30StepCheckYesNo1CHECK INPUT VOLTAGE TO SUNLOAD SENSOR.1) Turn the ignition switch to ON.2) Measure the input voltage to sunload sensor.Connector & terminal(i51) No. 2 (+) Chassis g

20、round (-):Is the voltage approx. 5 V?Go to step 3.Go to step 2.2CHECK HARNESS CONNECTOR BETWEEN A/C CONTROL MODULE AND SUNLOAD SENSOR.1) Turn the ignition switch to OFF. 2)Disconnect the connectors from A/C control module.3)Measure the resistance of harness between A/C control module and sunload sensor.Connector & terminal(i51) No. 2 (B283) No. 16:Is the resistance less than 1W?Go to step 3.Repair the har- ness between A/C control module and sunload sen- sor.3CHECK HARNESS CONNECTOR BETWEEN A/C CONTROL MODULE AND SUNLOAD SENSOR.Measure the resistance of harn