Automatic Modes

The automatic HVAC system will warm up/cool down and maintain the interior temperature of the vehicle by controlling the A/C compressor clutch, blower motor, air temperature, mode and recirculation actuators to achieve the desired temperature. For fully automatic operation, both the blower and mode switches must be in the AUTO position. Blower speeds will change automatically based on inputs to the IPM. The IPM will always come back to the last settings after an ignition cycle or, if equipped, to the last settings of the driver by pressing the UNLOCK button on the remote keyless entry fob and placing the ignition in RUN.

Moisture tends to accumulate in the HVAC module assembly after the engine has been shut off. The IPM will purge the HVAC module of stale air and moisture to prevent window fogging. The mode actuator will move to the floor mode and run the low speed blower for 10 seconds in order to purge out the air and moisture. Purge mode can be bypassed if any manual modes are selected.

In cold temperatures, the automatic HVAC system will provide heat in the most efficient manner. On cold engine stand-up, in cold weather, the IPM moves the mode outlets to the windshield and operates the blower for 3 minutes. As coolant temperature increases, blower speed is increased. This is done to prevent windshield fogging. The purge can be bypassed if any manual modes are selected. To warm the interior quickly, maximum heat mode is used where the blower is at maximum speed, floor mode, air temperature actuator is in full hot and ambient air is being drawn in. The vehicle operator can select the extreme warm setting of 32°C (90°F), but the system will not warm the vehicle any faster. Once the desired temperature is reached, the blower motor, mode, recirculation and temperature will be adjusted automatically by the IPM.

In warm temperatures, the automatic HVAC system will provide A/C in the most efficient manner. On vehicle start up, the IPM will monitor for conditions that indicate the possible presence of moisture in the HVAC module. To avoid blowing hot air and moisture out at the driver, the IPM moves the mode door toward the floor and runs the blower for 3 seconds. This purge mode can be bypassed if any manual modes are selected. To cool the interior quickly, maximum cool mode is used where the blower is at maximum speed, air temperature actuator is in full cold and the recirculation actuator is drawing air from inside the vehicle. The vehicle operator can select the extreme cool setting of 16°C (60°F), but the system will not cool the vehicle any faster. Once the desired temperature is reached, the blower motor, mode, recirculation and temperature will be adjusted automatically by the IPM.