Air Flow Control

SYSTEM

Air Flow Control


DESCRIPTION

- A/C auto amp. changes gate voltage of power transistor and controls air flow continuously. When air flow is increased, voltage of blower motor gradually increases to prevent a sudden increase in air flow.
- In addition to manual control and automatic control, air flow control is compose of starting fan speed control, low coolant temperature starting control, high in-vehicle temperature starting control, and blower speed control at door motor operation.

AUTOMATIC AIR FLOW CONTROL

- A/C auto amp. decides target air flow depending on target air mix door opening angle.
- A/C auto amp. changes voltage of blower motor and controls air flow continuously so that air flow matches to target air flow.





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

STARTING FAN SPEED CONTROL

When blower motor is activated, A/C auto amp. gradually increases voltage of blower motor to prevent a sudden increase in discharge air flow. (T
1 T2 = approximately 8 seconds)
NOTE:





Do not perform the starting air flow control when the discharge outlet is set to DEF.

LOW COOLANT TEMPERATURE STARTING CONTROL






If the engine coolant temperature is 56�C (133�F) or less, to prevent a cold discharged air flow, A/C auto amp. suspends blower motor activation for the maximum 150 seconds depending on target air mix door opening angle. After this, voltage of blower motor is increased gradually, and blower motor is activated.

FAN SPEED CONTROL AT DOOR MOTOR OPERATION

When mode door motor is activated while air flow is more than the specified value, A/C auto amp. reduces temporarily fan speed so that mode door moves smoothly.

HIGH IN- TEMPERATURE STARTING CONTROL

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 3 seconds so that evaporator is cooled by refrigerant.