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.