GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Corvette 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Too Hot in Vehicle

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step clears the HVAC control module memory and checks for current air temperature actuator diagnostic trouble codes.

  1. Ambient air temperature must be above 3°C (38°F) in order for this A/C Compressor test to be run.

    2.

  2. The specified values are from the A/C System Performance Test

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

Connector End View Reference: HVAC Connector End Views

DEFINITION: The temperature cannot be adjusted, or the cooling is insufficient during A/C operation.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Recalibrate actuators. Refer to Actuator Recalibration .
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Diagnostic Trouble Code (DTC) List in Heating and Air Conditioning.

Does the scan tool display any DTC B0361, B0363, B0365, B0367, B0441 or B0446?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

Important: Ambient air temperature must be above 3°C (38°F).

  1. Cover the sunload sensor.
  2. Start the engine.
  3. Fully open all panel outlets.
  4. Adjust the temperature control to maximum cooling.
  5. Select PANEL (upper) mode.
  6. Adjust the blower speed to maximum.
  7. Ensure that the VENT (outside air) mode indicator is not illuminated.

Does the A/C compressor operate?

--

Go to Step 4

Go to HVAC Compressor Clutch Does Not Engage

4

Place the blower motor switch in each speed position.

Does the blower motor operate correctly for each speed position?

--

Go to Step 5

Go to Blower Motor Inoperative

5

Does the blower motor provide sufficient air flow?

--

Go to Step 6

Go to Blower Motor Malfunction

6
  1. Place the blower motor switch in the maximum speed position.
  2. Place the mode switch in the bi-level position.
  3. Place the outside air switch in the ON position.
  4. Place the recirculation switch in the ON position.

Does the recirculation door operate properly?

--

Go to Step 7

Go to Air Recirculation Malfunction

7

Perform the A/C system performance test. Refer to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning.

Does the system pass the A/C System Performance Test?

--

Go to Step 8

Go to Air Conditioning (A/C) System Performance Test in Heating, Ventilation and Air Conditioning

8
  1. Install a thermometer near the inside air temperature sensor.
  2. With a scan tool, observe the Inside Temp Sensor data parameters in the Heating and Air Conditioning data list.

Does the scan tool indicate that the sensor temperatures are within 3°C (5°F) of the thermometer temperatures?

--

Go to Step 10

Go to Step 9

9

Inspect for a blocked or malfunctioning inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you find and correct the condition?

--

Go to Step 20

Go to Step 13

10
  1. Turn the engine OFF.
  2. Install a scan tool.
  3. Cover the sunload sensor.
  4. Start the engine.
  5. Adjust driver side temperature to 22°C (72°F).
  6. With a scan tool, observe the Sun Load Sensor data parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the sunload sensor parameter is greater than the specified value?

4.3 V

Go to Step 11

Go to Step 15

11
  1. Uncover the sunload sensor.
  2. Direct a light source at the sunload sensor.

Does the voltage change?

--

Go to Step 12

Go to Step 15

12

Does the customer need to change the set temperature frequently to maintain comfort?

--

Go to Symptoms - HVAC Systems - Automatic

System OK

13

Inspect for poor connections at the harness connector of the inside air temperature sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 14

14
  1. Turn OFF the ignition.
  2. Test the inside air temperature sensor resistance. Refer to Sensor Resistance Table .

Does the resistance measure near the specified value?

--

Go to Step 16

Go to Step 17

15

Inspect for poor connections at the harness connector of the sunload sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 18

16

Inspect for poor connections at the harness connector of the HVAC control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

17

Replace the inside air temperature sensor. Refer to Inside Air Temperature Sensor Replacement .

Did you complete the replacement?

--

Go to Step 20

--

18

Replace the sunload sensor. Refer to Sun Load Sensor Replacement .

Did you complete the replacement?

--

Go to Step 20

--

19

Important: Perform the recalibration procedure for the HVAC control module.

Replace the HVAC control module. Refer to HVAC Control Module Replacement .

Did you complete the replacement?

--

Go to Step 20

--

20

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 3