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 or Manual.
  5. Select Module Setup.
  6. Select Afterblow Option.
  7. Upon selecting the afterblow option a asterix will appear next to the word afterblow meaning the function is enabled.
  8. Select the save option in the lower left of the screen.

When afterblow has been enabled the blower motor will operate for 2 minutes 30 seconds to 4 minutes after the engine has been in Key OFF for 30 minutes.

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 have operated during the latest key cycle.
    • The engine must be turned off for at least 30 minutes.
    • The system voltage must be at least 12 volts.