Air Temperature Malfunction
Air Temperature Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Reference Information
Schematic Reference
HVAC Schematics HVAC - Automatic
Connector End View Reference
Component Connector End Views 1-2 Shift Solenoid (SS) Valve (M30)
Description and Operation
* Air Delivery Description and Operation Air Delivery
* Air Temperature Description and Operation Air Temperature
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
Note: Check for bulletins before proceeding.
1. Ignition ON, move the blower motor switch into each speed position one at a time.
2. Verify that the blower motor operates properly in all speeds.
• If the blower motor does not operate properly in all speeds
Refer to Blower Motor Malfunction Blower Motor Malfunction
• If the blower motor does operate properly in all speeds
3. Using the scan tool observe the mode, temperature and recirculation door positions. Verify the scan tool HVAC actual and commanded door positions are within 4 counts of each other.
• If not within the specified range
Refer to DTC B0228, B0413, B0423, or B3779 HVAC - Automatic Circuit/System Testing
• If within the specified range
4. Engine ON, A/C ON, place the temperature control in the coldest position. Verify that the A/C compressor clutch engages.
• If the A/C compressor clutch does not engage
Refer to Air Conditioning Compressor Malfunction Air Conditioning Compressor Malfunction
• If the A/C compressor is engaged, but the air is insufficiently cooled
Refer to Air Conditioning (A/C) System Performance Test (Gas Engine with Electric Cooling Fan) Air Conditioning (A/C) System Performance Test (With Electric Cooling Fan)Air Conditioning (A/C) System Performance Test (Diesel Engine) Air Conditioning (A/C) System Performance Test (HP2) Air Conditioning (A/C) System Performance Test (Gas Engine with Engine Driven Fan) Air Conditioning (A/C) System Performance Test (With Engine Driven Fan)
• If the A/C compressor clutch is engaged and the air is sufficiently cooled
5. Turn the A/C OFF and place the temperature control in the warmest position.
• If the air is insufficiently heated
Refer to Heating Performance Diagnostic Heating Performance Diagnostic
• If the air is sufficiently heated
6. Engine OFF, ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item.
7. Verify the scan tool Right Sunload Sensor and Left Sunload Sensor parameters are within 3 counts of each other.
• If not within the specified range
Refer to DTC B0183 or B0188 B0183
• If within the specified range
8. Measure actual outside air temperature and actual temperature at each air outlet duct using a thermometer.
9. Verify the scan tool Outside Air Temp. Raw and each Duct Actual parameter is within 5 degrees of the thermometer reading.
• If any are not within the specified range
Refer to DTC B0158, B0163, B0173, B0178, B0509, or B0514 HVAC - Automatic
• If all are within the specified range
10. Measure actual inside air temperature using a thermometer.
11. Verify the scan tool Inside Air Temp. Sensor is within 5 degrees of the thermometer reading.
• If not within the specified range
Refer to Inside Air Temperature Sensor Circuit Malfunction
• If within the specified range
12. Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor Raw parameter.
13. Verify the reading is between -35°C (-39°F) and 98°C (208°F) and changes with evaporator air temperature changes.
• If not within the specified range
Refer to DTC B3933 HVAC - Automatic
• If within the specified range
14. All OK
Circuit/System Testing
Inside Air Temperature Sensor Circuit Malfunction
1. Ignition OFF, disconnect the harness connector at the inside air temperature sensor.
2. Test for less than 10 ohms between the ground circuit terminal C and ground.
• If 10 ohms or greater
1. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 10 ohms
3. Ignition ON
4. Verify a test lamp illuminates between the control circuit terminal B and ground.
• If the test lamp does not illuminate
1. Ignition OFF
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the HVAC control module.
• If the test lamp does illuminate
5. Ignition OFF
6. Test for less than 10 ohms between the low reference circuit terminal D and ground.
• If 10 ohms or greater
1. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the HVAC control module.
• If less than 10 ohms
7. Ignition ON
8. Verify the scan tool Inside Air Temp Sensor parameter is less than -35°C (-39°F).
• If -35°C (-39°F) or greater
1. Ignition OFF, disconnect the X1 harness connector at the HVAC control module.
2. Test for infinite resistance between the signal circuit terminal A and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the HVAC control module.
• If less than -35°C (-39°F)
9. Install a 3-amp fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B.
10. Verify the scan tool Inside Air Temp Sensor parameter is greater than 85°C (185°F).
• If 85°C (185°F) or less
1. Disconnect the X1 harness connector at the HVAC control module.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V
3. Ignition OFF
4. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the HVAC control module.
• If greater than 85°C (185°F)
11. Replace the inside air temperature sensor.
Component Testing
1. Ignition OFF, disconnect the harness connector at the appropriate temperature sensor.
2. Measure the resistance between the signal terminal A or 1 and the low reference terminal B or 2.
3. Verify the resistance is within 5% of the readings contained in the Sensor Resistance Table Electrical Specifications.
• If not within 5%
Replace the appropriate sensor
• If within 5%
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Duct Air Temperature Sensor Replacement - Lower Left Side Duct Air Temperature Sensor Replacement - Lower Left Side
* Duct Air Temperature Sensor Replacement - Lower Right Side Duct Air Temperature Sensor Replacement - Lower Right Side
* Duct Air Temperature Sensor Replacement - Upper Left Side Duct Air Temperature Sensor Replacement - Upper Left Side
* Duct Air Temperature Sensor Replacement - Lower Left Side Duct Air Temperature Sensor Replacement - Lower Left Side
* Air Conditioning Refrigerant Temperature Sensor Replacement Service and Repair
* Ambient Air Temperature Sensor Replacement Service and Repair
* Ambient Light Sensor Replacement Service and Repair
* Control Module References Control Module References for control module replacement, programming and setup