GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Bonneville 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Temperature Variation Between Driver and Passenger Outlets

Step

Action

Value(s)

Yes

No

Schematic Reference: HVAC Schematics

Definition: Temperature variation between driver and passenger A/C or heater outlets.

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, perform the Recalibrate all Motors command in Instrument Panel Module Special Functions.
  4. With a scan tool, observe the current DTC list in Instrument Panel Module.

Does the scan tool display any DTCs?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

When the A/C is ON, does the customer concern occur?

--

Go to Step 4

Go to Step 10

4

Important:: Ambient air temperature must be above 5°C (41°F).

  1. Cover the sunload sensor assembly.
  2. Start the engine.
  3. Fully open all panel outlets.
  4. Place the air temperature switch in the coldest position.
  5. Place the mode switch in the panel (upper) position.
  6. Place the blower motor switch in the maximum speed position.
  7. Place the right air temperature switch on the HVAC control module in the OFF position.
  8. Ensure that the VENT (outside air) indicator is not illuminated.

Is the difference between the right and left center panel outlet temperatures greater than the specified value?

6°C (10°F)

Go to Step 5

System OK

5

Perform the A/C system performance test.

Refer to Air Conditioning (A/C) System Performance Test .

Did you find and correct the condition?

--

Go to Step 24

Go to Step 6

6

Check the air temperature sensors for proper installation. Refer to the following procedures:

Did you find and correct the condition?

--

Go to Step 24

Go to Step 7

7
  1. Install a scan tool.
  2. Cover the sunload sensor assembly.
  3. Start the engine.
  4. Place the temperature switch in the 24°C (75°F) position.
  5. Place the right air temperature switch on the HVAC control module in the OFF position.
  6. With a scan tool, observe the Right and Left Solar Sensor data parameters in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Right and Left Solar Sensor data parameters are greater than the specified value?

224  Counts

Go to Step 8

Go to Step 19

8
  1. Uncover the sunload sensor assembly.
  2. Direct a light source at the right and then the left side of the sunload sensor assembly.

Do the counts change similarly and correspond to the proper side of the sunload sensor assembly?

--

Go to Step 9

Go to Step 19

9
  1. Install a thermometer near the following air temperature sensors:
    2. • Upper Right
    • Upper Left
    • Lower Right
    • Lower Left
  2. With a scan tool, observe the following data parameters in the Instrument Panel Module HVAC Sensor data list:
    3. • Right AC Duct Temp
    • Left AC Duct Temp
    • Right Htr Duct Temp.
    • Left Htr Duct Temp.

Does the scan tool indicate sensor temperatures near the thermometer temperatures within the specified range?

+3 to -3°C

(+5 to -5°F)

System OK

Go to Step 17

10
  1. Cover the sunload sensor assembly.
  2. Start the engine.
  3. Fully open all panel outlets.
  4. Place the temperature switch in the warmest position.
  5. Place the mode switch in the FLOOR (lower) position.
  6. Place the blower motor switch in the maximum speed position.
  7. Place the right air temperature switch on the HVAC control module in the OFF position.

Is the difference between the right and left outlet temperatures greater than the specified value?

6°C (10°F)

Go to Step 11

System OK

11

Inspect the cooling system for the following:

  1. A low coolant level.
  2. A loose or worn accessory drive belt
  3. A leaking radiator hose or heater hose
  4. A kinked radiator hose or heater hose
  5. A missing radiator cap pressure seal
  6. A leaking radiator cap

Did you find and correct the condition?

--

Go to Step 24

Go to Step 12

12

Perform the Heating Performance Diagnostic. Refer to Heating Performance Diagnostic .

Did you find and correct the condition?

--

Go to Step 24

Go to Step 13

13

Inspect the air temperature sensors for proper installation. Refer to the following procedures:

Did you find and correct the condition?

--

Go to Step 24

Go to Step 14

14
  1. Install a scan tool.
  2. Cover the sunload sensor assembly.
  3. Start the engine.
  4. Place the temperature switch in the 24°C (75°F) position.
  5. Place the right air temperature switch on the HVAC control module in the OFF position.
  6. With a scan tool, observe the Right and Left Solar Sensor data parameters in the Instrument Panel Module Open/Short Data list.

Does the scan tool indicate that the Right and Left Solar Sensor data parameters are greater than the specified value?

224  Counts

Go to Step 15

Go to Step 19

15
  1. Uncover the sunload sensor assembly.
  2. Direct a light source at the right and then the left side of the sunload sensor assembly.

Do the counts change similarly and correspond to the proper side of the sunload sensor assembly?

--

Go to Step 16

Go to Step 19

16
  1. Install a thermometer near the following air temperature sensors:
    2. • Upper Right
    • Upper Left
    • Lower Right
    • Lower Left
  2. With a scan tool, observe the following data parameters in the Instrument Panel Module HVAC Sensor data list:
    3. • Right AC Duct Temp
    • Left AC Duct Temp
    • Right Htr Duct Temp.
    • Left Htr Duct Temp.

Does the scan tool indicate sensor temperatures near the thermometer temperatures within the specified range?

+3 to -3°C

(+5 to -5°F)

System OK

Go to Step 17

17

Inspect for poor connections at the harness connector of the suspect 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 24

Go to Step 18

18

Test the suspect temperature sensor resistance. Refer to Sensor Resistance Table .

Does the resistance measure near the Sensor Resistance Table value?

--

Go to Step 20

Go to Step 22

19

Inspect for poor connections at the harness connector of the sunload sensor assembly . 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 24

Go to Step 21

20

Inspect for poor connections at the harness connectors of the instrument panel integration 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 24

Go to Step 23

21

Replace the sunload sensor assembly. Refer to Sunload and Twilight Sentinel Sensor Replacement in Instrument Panel, Gauges, and Console.

Did you complete the replacement?

--

Go to Step 24

--

22

Replace the suspect temperature sensor. Refer to the following procedures:

Did you complete the replacement?

--

Go to Step 24

--

23

Important:: Perform the recalibration procedure for the instrument panel integration module.

Replace the instrument panel integration module. Refer to Instrument Panel Module Replacement in Body Control System.

Did you complete the replacement?

--

Go to Step 24

--

24

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2