Nissan Maxima. Instruction — part 711

HAC-20

< SYSTEM DESCRIPTION >

[WITH COLOR DISPLAY]

INTAKE DOOR CONTROL SYSTEM

INTAKE DOOR CONTROL SYSTEM

System Diagram

INFOID:0000000010050956

System Description

INFOID:0000000010050957

The intake doors are automatically controlled by the temperature setting, ambient temperature, in-vehicle tem-

perature, intake temperature, amount of sunload and ON/OFF operation of the compressor.

SYSTEM OPERATION

The intake door control judges intake door position based on the ambient temperature, the intake air tempera-

ture and the in-vehicle temperature. When in shifting mode position D/F, if the DEF or OFF switches are

pressed, or when the A/C switch is OFF, the A/C auto amp. sets the intake door to the FRE position.

Door Motor Circuit

AWIIA1378GB

AWIIA1066GB

INTAKE DOOR CONTROL SYSTEM

HAC-21

< SYSTEM DESCRIPTION >

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Intake Door Control Specification

JPIIA0634GB

HAC-22

< SYSTEM DESCRIPTION >

[WITH COLOR DISPLAY]

BLOWER MOTOR CONTROL SYSTEM

BLOWER MOTOR CONTROL SYSTEM

System Diagram

INFOID:0000000010050958

System Description

INFOID:0000000010050959

Fan 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 airflow volume.

When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flow-

ing.

SYSTEM OPERATION

System Operation

• For airflow, the instruction 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 airflow, it changes the duty ratio of the blower

motor drive signal to prevent the airflow from suddenly increasing.

• There are the following types of airflow control: starting airflow con-

trol, starting airflow control at low coolant temperature, starting air-

flow control at high in-vehicle temperature, and airflow control at

actuator operation in addition to instruction control, normal automatic

airflow control.

Normal Automatic Airflow Control

• When the target temperature is set by the temperature control dial of A/C and AV switch assembly, 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 airflow, continuously,

so that the airflow becomes the target airflow.

• The minimum airflow will change according to the sunload when the air discharge outlet is VENT or B/L.

AWIIA1379GB

AWIIA1094GB

BLOWER MOTOR CONTROL SYSTEM

HAC-23

< SYSTEM DESCRIPTION >

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Fan Speed Control Specification

Starting Airflow Control

• When starting the automatic control of airflow, 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 airflow changes from LO to HI is approximately 8 seconds.

• It becomes the starting airflow control at low coolant temperature according to the calculation result of the A/

C auto amp. and engine coolant temperature [approximately 56

°C (133°F) or less] during the automatic air-

flow control.

• Do not perform the starting airflow 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 56

°C (133°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

56

°C (133°F), and then the fan 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 fan speed rises gradually

to the objective speed over a time period of 3 seconds or less (actual time depends on the objective fan

speed).

JPIIA0635GB