The Instrument Panel Integration Module (IPM) can access three additional purge modes when certain conditions exist:

When the system is powered up, it is desirable to purge the system of stale air and/or redirect it to avoid window fogging or other undesirable conditions. When the ignition is turned on and the HVAC system is in the AUTO mode, the IPM will determine if any of the undesirable conditions exist. The IPM will then select the purge mode to eliminate the undesirable condition.

Moisture tends to accumulate in the heater and evaporator module assembly after the engine has been shut off. When the engine is restarted and the A/C system turns on this moisture may be expelled from the windshield or instrument panel outlets and cause window fogging.

On start-up the IPM checks for indications that this may occur. If the IPM determines that window fogging can occur, the blower operation is delayed until the engine coolant temperature reaches 38°C (126°F). The defroster door is closed and the A/C door is positioned to direct air out of the heater outlets, and runs the blower at low speed.

Normal purge mode is bypassed if any manual mode is chosen.

In cold weather, moist breath air from vehicle occupants may condensate on the windshield.

On cold engine start-up, the IPM checks for indications that this may occur. If so, the IPM positions the doors to direct air out of the windshield outlets and operates the blower.

Cold purge mode is bypassed if any manual mode is chosen.

Moisture tends to accumulate in the heater and evaporator module assembly after the engine has been shut off. When the engine is restarted and the A/C system turns on, this moisture may be expelled from the instrument panel outlets toward the front seat occupants.

On start-up, the IPM checks for indications that this may occur. If so, the IPM positions the A/C door to direct air toward the floor and the A/C outlets. The blower motor operates.

A/C purge mode is bypassed if any manual mode is chosen.