Recirculation Mode

When the recirculation switch is pressed, a signal is sent from the HVAC control module to the recirculation actuator through the recirculation door control circuit. The recirculation actuator moves into the recirculation mode. This brings air from inside the vehicle instead of air from the outside.

The rear fuse block provides power to the recirculation actuator through the ignition 3 voltage circuit. Ground is provided by the low reference circuit, the HVAC control module and ground circuit. Power and ground are provided to the HVAC control module by the underhood fuse block on the battery positive and ground circuit.

The recirculation actuator is an electronic stepper motor with feedback potentiometers. Zero volts drives the actuator in one direction while 5 volts moves the actuator in the opposite direction. When the actuator receives 2.5 volts, actuator rotation stops. A 5 volt reference signal is sent out over the 5 volt reference circuit, from the HVAC control module, to the recirculation actuator. When a desired recirculation setting is selected, whether manual or automatic, the logic circuit is used to determine the recirculation door position signals value. A separate 5 volt reference is sent from the HVAC control module to the logic circuit. The HVAC control module software uses this reference voltage to determine the recirculation actuators position through the recirculation position signal circuit. The motor moves the recirculation door to the desired position. Ground for the recirculation actuator is provided by the low reference circuit and HVAC control module.

The recirculation mode can be used in both automatic and manual operation. The only time recirculation is not available is when FRONT DEFROST is selected. The recirculation icon on the VF display will flash to alert the driver that recirculation mode is not available. Pressing the recirculation switch, from the OFF position, will set the HVAC control module into automatic mode.

When manually selected, recirculation will stay on until either the vehicle operator selects outside air, by pressing the RECIRCULATION switch, or the HVAC control module automatically moves the recirculation actuator. Manual recirculation will have to be set every time the ignition switch is cycled.

When the temperature switch is set to 16°C (60°F), the HVAC control module will go into recirculation mode to cool the vehicle as quickly as possible. The recirculation icon on the display will not illuminate, but the recirculation mode can be viewed on the scan tool. When the temperature switch is set to 32°C (90°F), the HVAC control module will go into outside air mode to warm the vehicle as quickly as possible. This mode can be viewed on the scan tool.