Circuit/System Verification

WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Check for bulletins before proceeding.

Ignition ON, place the blower motor switch in each speed position. Verify that the blower motor operates properly in each position.
- If the blower motor does not operate properly in all speeds, refer to Blower Motor Malfunction .
Using the scan tool observe the mode, temperature and recirculation door positions. Verify the actual and commanded door positions are within 4 counts of each other.
- If not within the specified range, refer to Circuit/System Testing DTC B0228, B0413, B0423, or B3779
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 compressor clutch does not engage, refer to Air Conditioning Compressor Malfunction
- If the A/C compressor is engaged, but air is insufficiently cooled. Refer to Air Conditioning (A/C) System Performance Test (Diesel Engine) or Air Conditioning (A/C) System Performance Test (Gas Engine w/ Electric Cooling Fan) or Air Conditioning (A/C) System Performance Test (Gas Engine w/Engine Driven Fan) or Air Conditioning (A/C) System Performance Test (HP2) .
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 .
Engine OFF, ignition ON, cover the sunload sensor assembly with a shop towel or other suitable item. 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 Sun Load Sensor Circuit Malfunction.
Measure actual outside air temperature using a thermometer. Compare this value to the scan tool Outside Air Temp. Raw parameter. The measured temperature should be within 5 degrees of parameter.
- If not within the specified range, refer to Ambient Air Temperature Sensor Circuit Malfunction.
Measure actual inside air temperature using a thermometer. Compare this value to the scan tool Inside Air Temp. Sensor parameter and Aux. Inside Air Temp. parameter. The measured temperature should be within 5 degrees of parameter.
- If not within the specified range, refer to Inside Air Temperature Sensor Circuit Malfunction.
Measure actual temperature using a thermometer at each of the duct temperature sensors. Compare this value to the appropriate scan tool Duct Actual parameter. The measured temperature should be within 5 degrees of appropriate Duct Actual parameter.
- If not within the specified range, refer to Duct Temperature Sensor Circuit Malfunction.
Ignition ON, observe the scan tool A/C Evaporator Temperature Sensor parameter. The reading should be between -39°F (-35°C) and 208°F (98°C) and change with evaporator air temperature changes.
- If not within the specified range, refer to Evaporator Air Temperature Sensor Circuit Malfunction.