HVAC Control Components: Afterblow

Afterblow is a feature that dries the evaporator core by operating the blower motor after the engine is turned off. This reduces the amount of microbial growth that can create undesirable odors. The vehicle does not come equipped with the afterblow feature turned on. If the afterblow feature is required due to an odor concern, it must be turned on by the scan tool.

The following conditions must be met for afterblow to operate:

• The A/C compressor operated for more than 10 seconds.
• The A/C compressor, after operating for more than 10 seconds has not been deactivated for more than 10 minutes.
• The system voltage is at least 11 volts to start and 10 volts to continue to run.
• The ignition has been in the OFF position for at least 20 minutes.

Once the above conditions have been met the following sequence of events will occur:

• The blower will run for 4 minutes at 59 percent blower speed.
• The recirculation door moves to outside air position.
• The mode valve moves to the floor position.