Optional After Blow Body Control Logic

NOTE: The HVAC After blow function is not enable from the factory. To enable function, refer to "Special Functions" accessed through the Tech 2.

The HVAC HI Blower Fan Output can be requested by either the HI Blower Switch Input or the HVAC After Blow Function. When requested by the HI blower switch the BCM receives the switch input and switches the blower relay to battery. This energizes the blower relay coil and turns the blower motor on High.

The HVAC After Blow function is used to eliminate the odor associated with A/C usage. The "After Blow" is a method whereby the HVAC blower is run for a few minute approximately 50 minutes after the vehicle is turned Off in order to physically blow off excess condensation and eliminate odors.

The PCM sends vehicle speed, air intake temperature (use for ambient temperature), and A/C clutch status to the BCM. When the BCM receives the above information from the PCM and determines the A/C has been engaged during the ignition cycle, the After Blow is requested to occur after vehicle power down.

Once the request for After Blow is made, the BCM monitor air intake temperature to determine the duration of the After Blow required. A sufficiently high ambient temperature, approximately 30°C (86°F) or higher, causes an After Blow event of approximately 3 minutes. A lower ambient temperature, below 30°C (86°F), allows for a shorter duration, approximately 32 seconds. The vehicle speed must have met or exceeded 48 km/h (30 mph) to cause an After Blow event when all other conditions have been met

After vehicle power down, After Blow occurs after a delay. In the event that the ignition is cycled On during the delay period or the After Blow event, the After Blow output is turned off.