With 7 Inch Display

BLOWER MOTOR CONTROL SYSTEM


System Description

Blower speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle tempera- ture, intake temperature, amount of sunload and air mix door position.
By pressing the AUTO switch, the blower motor starts to gradually increase air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flowing.

SYSTEM OPERATION

System operation





- For air flow, the manual selection (1-7) with the fan control dial has priority.
- If the AUTO switch is pressed or if the DEF switch is pressed while in the OFF condition, it changes to the automatic control by A/C auto amp.
- When increasing the air flow, it changes the duty ratio of the blower motor drive signal to prevent the air flow from suddenly increasing.
- There are the following types of air flow control: starting air flow control, starting air flow control at low coolant temperature, starting air flow control at high in-vehicle temperature, and air flow control at actuator operation in addition to manual control, normal automatic air flow control.

Normal automatic air flow control
- When the target temperature is set by the temperature control dial of preset switch, the A/C auto amp. performs the calculation and decides the target according to the signal from each sensor.
- The A/C auto amp. changes the duty ratio of blower motor drive signal and controls the air flow continuously so that the air flow becomes the target air flow.
- The minimum air flow will change according to the sunload when the air discharge outlet is VENT or B/L.

Fan Speed Control Specification

Starting air flow control





- When starting the automatic control of air flow, the system gradually increases the duty ratio of the blower motor drive signal to prevent too much air from blowing.
- The time period from when the air flow changes from LO to HI is approximately 8 seconds.
- It becomes the starting air flow control at low coolant temperature according to the calculation result of the A/C auto amp. and engine coolant temperature [approximately 58�C (136�F) or less] during the automatic air flow control.
- Do not perform the starting air flow control when the air discharge outlet is set to DEF.

Starting Fan Speed Control
Start up from COLD SOAK Condition (Automatic mode)
In cold start up condition where the engine coolant temperature is below 58�C (136�F), the blower does not operate for a short period of time (up to 150 seconds). The exact start delay time varies depending on the ambient temperature and engine coolant temperature.
In the most extreme case (very low ambient temperature) the blower start delay is 150 seconds as described above. After this delay, the blower will operate at low speed until the engine coolant temperature rises above 58 °C (136�F), and then the blower speed increases to the objective speed.
Start up from usual or HOT SOAK Condition (Automatic mode)
The blower will begin operation momentarily after the AUTO switch is pressed. The blower speed rises gradually to the objective speed over a time period of 3 seconds or less (actual time depends on the objective blower speed).