GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Bonneville 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 Heating Insufficient

Step

Action

Value(s)

Yes

No

1

Did you perform the HVAC and Engine Cooling Diagnostic System Checks?

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Go to Step 2

Go to

    •  Diagnostic System Check in HVAC Systems-Automatic
    •  Diagnostic System Check in HVAC Systems-Manual
    •  Diagnostic System Check in Engine Cooling

2
  1. Turn the engine OFF.
  2. Ensure that the engine temperature is cool.
  3. Check the coolant level in the radiator and the reservoir.

Is the coolant level low?

--

Go to Step 6

Go to Step 3

3
  1. Connect the scan tool.
  2. Start the engine.
  3. Select Diagnostics/Body/Heating and Air Conditioning/Data Display/HVAC System Data.
  4. Monitor the engine coolant temperature.

Does the coolant temperature increase steadily to the normal operating temperature?

--

Go to Step 4

Go to Engine Fails To Reach Normal Operating Temperature in Engine Cooling

4

Feel the inlet and the outlet hoses of the heater core.

Do the inlet and the outlet hoses feel hot?

--

Go to Step 5

Go to Step 8

5

Check for an inoperative actuator or a sticking mode or temp door.

Are the actuators and doors operating properly?

--

Go to Step 7

Go to Step 12

6

Inspect the cooling system for signs of leakage. Refer to Cooling System Leak Testing in Engine Cooling.

Did you find a leak in the system?

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Go to Step 9

Go to Step 10

7
  1. Inspect and repair the system for an external air leak at the HVAC case housing seals.
  2. Inspect and repair for a misaligned heater duct. Refer to Instrument Panel Insulator Panel Replacement - Right Side or Instrument Panel Insulator Panel Replacement - Left Side in Instrument Panel, Gauges and Console.

Did you complete the repair?

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Go to Step 13

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8
  1. Inspect the hoses for kinks or other obstructions.
  2. Flush or replace the obstructed heater core.

Did you complete the repair?

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Go to Step 13

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9

Repair the cooling system leak.

Did you complete the repair?

--

Go to Step 10

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10
  1. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  2. Recheck the cooling system for signs of leakage. Refer to Cooling System Leak Testing in Engine Cooling.

Did you complete the repair?

--

Go to Step 13

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11
  1. Inspect the heater core for bent fins or other obstructions.
  2. Repair or replace the heater core. Refer to Heater Core Replacement .

Did you complete the repair?

--

Go to Step 13

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12

Repair or replace the actuator or door.

Did you complete the repair?

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Go to Step 13

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13

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2