Air Distribution Control

Air distribution control
To control the air distribution within the cabin the ATC ECU signals the servo motor controlling the distribution flaps in the heater assembly to move to the flaps to the appropriate position.

In the automatic and economy modes, if the LH or RH temperature selections are set to LO or HI, air distribution is fixed as follows:
^ If one is set to LO and one is set to a specific temperature, to face level only.
^ If one is set to HI and one is set to a specific temperature, to footwells only.
^ If one is set to LO and one is set to HI, to face level and footwells.

When specific LH and RH temperature selections are set, air distribution is determined from the target air outlet temperatures. For higher target air outlet temperatures, air distribution is set to footwells only. For lower target air outlet temperatures, air distribution is set to face level only. For intermediate target air outlet temperatures, air distribution is set to face level and footwells. When the air distribution is set to face level and footwells, the ATC ECU varies the bias between the footwells and the face level outlets, in three stages, to provide a gradual transition of air distribution from footwells only to face level only. The three stages of bias are also employed when the air distribution is manually selected to face level and footwells.

During warm-up, the air distribution changes to face level and footwells for a period, then reverts to footwells only. The period of air distribution at face level and footwells can be cancelled by pressing and holding the on/off and defrost mode switches, then turning the ignition switch from off to on. Pressing and holding the AUTO and defrost switches, then turning the ignition switch from off to on, restores the period of air distribution at face level and footwells.