Air Flow Control

SYSTEM

AUTOMATIC AIR CONDITIONING SYSTEM : Air Flow Control


DESCRIPTION

- In addition to manual air flow control and automatic air flow control, air flow control also includes starting air flow control, starting air flow control when coolant temperature is low, starting air flow control when interior temperature is high, and air flow control when motor is operating.






AUTOMATIC AIR FLOW CONTROL

- A/C auto amp. determines target air flow according to target air mix door opening angle.
- A/C auto amp. changes voltage to power transistor gate and controls air flow in a continuous range (no steps) so that target air flow is achieved. At this time, the voltage applied to the blower fan motor is changed at the rate of 1.0 V per second in order to prevent any sudden changes in air flow.





- When air outlet is VENT or B/L, the minimum air flow is changed depending on sunload.

STARTING AIR FLOW CONTROL






When blower fan motor is activated, A/C auto amp. changes the voltage to the power transistor gate, and gradually increases the voltage to the blower fan motor, in order to prevent a sudden increase in discharge air flow (approximately 10.5 seconds for air flow to reach HI
from LOW).
NOTE:
When outlet is DEF, air flow control at motor start is not performed.

STARTING AIR FLOW CONTROL AT LOW HEATER FULID TEMPERATURE






When blower fan motor starts, the A/C auto amp. suspends blower motor activation for a maximum of 150 seconds, according to the target air mix door position. This prevents cold air from being discharged. After this, voltage applied to power transistor gate is increased gradually, and the blower fan motor starts.

STARTING AIR FLOW CONTROL AT HIGH INTERIOR AIR TEMPERATURE

When evaporator temperature is high [intake air temperature sensor value is 35�C (95�F) or more], to prevent a hot discharged air flow, A/C auto amp. suspends blower motor activation for approximately three seconds so that evaporator is cooled by refrigerant.

AIR FLOW CONTROL AT MOTOR OPERATION

If the mode door motor starts when the air flow corresponds to a voltage of 8.6 V or more applied to the blower fan motor, the A/C auto amp. performs control that fixes the voltage applied to the blower fan motor at 8.5 V, temporarily decreasing the air flow and ensuring that the mode door operates smoothly.

MANUAL AIR FLOW CONTROL

When the fan switch is operated, automatic control is cancelled and the desired fan speed (1 - 7) can be selected.