GM Service Manual Online
For 1990-2009 cars only

The afterblow mode can be enabled using the scan tool. The afterblow mode allows the blower motor to operate after the engine has been turned off. This operation of the blower motor dries the evaporator core, which reduces the amount of microbial growth which can create undesirable odors.

Use the following procedure in order to enable the afterblow mode:

  1. Connect the scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Select HVAC Module.
  4. Select HVAC Systems Automatic.
  5. Select Special Functions.
  6. Select HVAC.
  7. Select Afterblow Option.
  8. Select ENTER to enable the afterblow.
  9. When done, use the soft key to save changes.

When afterblow has been enabled by the scan tool the blower motor will operate between medium and high speed for 4 minutes after the engine has been turned off.

The following conditions must be met for the HVAC module to operate the afterblow:

    • The outside air temperature must be at least 21°C (70°F).
    • The A/C compressor must operate for more than 2 minutes.
    • The engine must be turned off for at least 45 minutes.
    • The system voltage must be at least 12 volts.