HVAC - Automatic
DTC B0163 or B3933
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
DTC Descriptors
DTC B0163 06
- Passenger Compartment Temperature Sensor Circuit Short to Ground or Open
DTC B3933 06
- Evaporator Temperature Sensor Circuit Short to Ground or Open
Diagnostic Fault Information
Circuit/System Description
The HVAC control module supplies the evaporator temperature and inside air temperature sensors with a low reference circuit and 5-volt signal circuit. The HVAC control module determines the voltage drop across the sensors, which is proportional to temperature. As the air temperature increases, the sensor resistance decreases. As the air temperature decreases, the sensor resistance increases. The inside air temperature sensor assembly has an internal fan that draws air across the sensor and is controlled by the HVAC control module. The internal fan motor is connected to body ground.
Conditions for Running the DTC
Ignition ON.
Conditions for Setting the DTC
B0163
The HVAC control module detects the inside air temperature sensor signal circuit is less than -36°C (-38°F) or more than 215°C (419°F) for more than 15 seconds.
B3933
The HVAC control module detects the evaporator temperature sensor signal circuit is less than -36°C (-38°F) or more than 215°C (419°F) for more than 15 seconds.
Action Taken When the DTC Sets
B0163
* The system operates using a default value.
* The HVAC control module will display dashes for outside air temperature.
* The DIC will display SERVICE A/C SYSTEM.
B3933
* The A/C compressor is disabled
* The DIC will display SERVICE A/C SYSTEM.
Conditions for Clearing the DTC
* The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
* The history DTC will clear after 100 fault-free ignition cycles.
Reference Information
Schematic Reference
HVAC Schematics (HVAC - Automatic)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Automatic HVAC Description and Operation (HVAC - Automatic)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal listed below and ground.
* Passenger compartment temperature sensor circuit terminal D
* Evaporator temperature sensor circuit terminal B
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Ignition ON, verify the appropriate scan tool Temperature Sensor parameter is greater than 215°C (419°F).
• If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the HVAC control module.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal listed below. Verify the appropriate scan tool Temperature Sensor parameter is less than -36°C (-38°F).
* Passenger compartment temperature sensor circuit terminal D
* Evaporator temperature sensor circuit terminal B
• If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
5. If all circuits test normal, test or replace the temperature sensor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heater and Air Conditioning Control Wiring Harness Replacement (w/Evaporator Temperature Sensor) (HVAC - Automatic)
* Inside Air Temperature Sensor Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for HVAC control module replacement, setup and programming