HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS) > Diagnostic Procedure for Sensors

EVAPORATOR SENSOR

WIRING DIAGRAM:

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1.CHECK EVAPORATOR SENSOR.

1) Turn the ignition switch to OFF.

2) Remove the glove box.

3) Disconnect the connector from evaporator sensor.

4) Measure the resistance between connector terminals of the evaporator sensor.

Terminals

No. 1 — No. 3:

Is the resistance approximately 2.7 kΩ at 20°C (68°F)?

Replace the evaporator sensor.

2.CHECK INPUT SIGNAL FOR EVAPORATOR SENSOR.

1) Turn the ignition switch to ON.

2) Measure the voltage between connector (B256) terminal and chassis ground.

Connector & terminal

(B256) No. 1 (+) — Chassis ground (−):

Is the voltage approx. 5 V?

3.CHECK AUTO A/C CONTROL MODULE OUTPUT SIGNAL.

1) Turn the ignition switch to OFF.

2) Remove the auto A/C control module.

3) Turn the ignition switch to ON.

4) Measure the voltage between connector terminals of auto A/C control module.

Connector & terminal

(i49) No. 2 (+) — (i48) No. 16 (−):

Is the voltage approx. 5 V?

4.CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND EVAPORATOR SENSOR.

1) Turn the ignition switch to OFF.

2) Disconnect the connector from the auto A/C control module.

3) Measure the resistance of harness between auto A/C control module and evaporator sensor.

Connector & terminal

(B256) No. 1 — (i49) No. 2:

Is the resistance less than 1 Ω?

Repair the open circuit of harness between auto A/C control module and evaporator sensor.

5.CHECK HARNESS CONNECTOR BETWEEN AUTO A/C CONTROL MODULE AND EVAPORATOR SENSOR.

Measure the resistance of harness between auto A/C control module and evaporator sensor.

Connector & terminal

(B256) No. 3 — (i48) No. 16:

Is the resistance less than 1 Ω?

Repair the open circuit of harness between auto A/C control module and evaporator sensor.

6.CHECK POOR CONTACT.

Check poor contact of auto A/C control module connector.

Is there poor contact in the connector?

Repair the connector.

Replace the auto A/C control module.