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Manual Three Zone Temperature Control






B1032-Evaporator Temperature Sensor Circuit High

For a complete wiring diagram, refer to.

Theory of Operation

The Evaporator Temperature Sensor is a variable resistor that changes in conjunction with temperature, or otherwise known as a thermistor. The Evaporator Temperature Sensor is located in the HVAC housing downstream of the A/C evaporator. The A/C Heater Control module monitors the evaporator temperature by monitoring the voltage change of the Evaporator Temperature Sensor Signal circuit. If the monitored voltage drops below or rises above a predetermined voltage, a DTC will set.

When Monitored: With the ignition on.

Set Condition: The Evaporator Temperature Sensor voltage input to the A/C Heater Control is greater than 4.95 volts for a continuous period of five seconds. If the A/C Heater Control detects a valid voltage, the Diagnostic Trouble Code (DTC) will change from Active to Stored and will stay in the controllers memory for 100 ignition cycles.






Always perform the HVAC Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to => Non-DTC Based
Diagnostics. HVAC Pre-Diagnostic Troubleshooting Procedure

Test Step 1 - CHECK IF THE DTC IS ACTIVE

Ignition on, engine not running.

Using the scan tool, read HVAC DTCs.

Is this DTC active?

Yes

Go to Test Step 2 => [ Test Step 2 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL
CIRCUIT VOLTAGE ]

No

Go to Test Step 7 => [ Test Step 7 - CHECK THE WIRING AND CONNECTORS ]

Test Step 2 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT VOLTAGE







Turn the ignition off to the lock position.

Disconnect the Evaporator Temperature Sensor harness connector.

Due to the small terminal and pin size of the Evaporator Temperature Sensor and harness connector, make sure to not damage the terminals in this process.

Connect a jumper wire between the (C21) Evaporator Temperature Sensor Signal circuit and the (C121) Sensor Ground circuit in the Evaporator Temperature Sensor harness connector.

Ignition on, engine not running.

Using the scan tool, read the Evaporator Temperature Sensor voltage.

Is the voltage below 0.1 of a volt?

Yes

Replace the Evaporator Temperature Sensor in accordance with the Service Information.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Go to Test Step 3 => [ Test Step 3 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL
CIRCUIT FOR A SHORT TO VOLTAGE ]

Test Step 3 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE







Turn the ignition off to the lock position.

Disconnect the jumper wire from the Evaporator Temperature Sensor harness connector.

Disconnect the A/C Heater Control C2 harness connector.

Ignition on, engine not running.

Measure the voltage of the (C21) Evaporator Temperature Sensor Signal circuit

Is there any voltage present?

Yes

Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to voltage.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Go to Test Step 4 => [ Test Step 4 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL
CIRCUIT FOR AN OPEN ]
Test Step 4 - CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR AN OPEN







Turn the ignition off to the lock position.

Measure the resistance of the (C21) Evaporator Temperature Sensor Signal circuit between the A/C Heater Control C2 harness connector and the Evaporator Temperature Sensor harness connector.

Is the resistance above 1.0 Ohm?

Yes

Repair the (C21) Evaporator Temperature Sensor Signal circuit for an open or high resistance.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Go to Test Step 5 => [ Test Step 5 - CHECK THE (C121) SENSOR GROUND CIRCUIT FOR AN OPEN ]

Test Step 5 - CHECK THE (C121) SENSOR GROUND CIRCUIT FOR AN OPEN







Measure the resistance of the (C121) Sensor Ground circuit between the A/C Heater Control C2 harness connector and the Evaporator Temperature Sensor harness connector.

Is the resistance above 1.0 Ohm?

Yes

Repair the (C121) Sensor Ground circuit for an open.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Go to Test Step 6 => [ Test Step 6 - CHECK THE EVAPORATOR TEMPERATURE SENSOR ]

Test Step 6 - CHECK THE EVAPORATOR TEMPERATURE SENSOR

Ignition on, engine not running.

With the scan tool, erase HVAC DTCs.

Turn the ignition off to the lock position.

Replace the Evaporator Temperature Sensor.

Ignition on, engine not running.

Using the scan tool read HVAC DTCs.

Does this DTC reset?

Yes

Replace and program the A/C Heater Control.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Test complete.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

Test Step 7 - CHECK THE WIRING AND CONNECTORS

The conditions necessary to set the DTC are not present at this time.

Using the scan tool, check the Environmental Data to help identify the conditions in which the DTC was set.

Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.

Wiggle the wiring and connectors while checking for shorted and open circuits.

Were there any problems found?

Yes

Repair as necessary.

Perform the HVAC Verification Test. Refer to => Non-DTC Based Diagnostics. HVAC Verification Test

No

Test complete.