Nissan Maxima Service and Repair Manual: Blower motor control system

System Diagram

Nissan Maxima. System Diagram

System Description

Fan speed is automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, 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 flowing.

SYSTEM OPERATION

System Operation

Nissan Maxima. System Operation

  • For airflow, 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 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 control, starting airflow control at low coolant temperature, starting airflow control at high in-vehicle temperature, and airflow control at actuator operation in addition to manual 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.

Fan Speed Control Specification

Nissan Maxima. 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 56C (133F) or less] during the automatic airflow 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 56C (133F), 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 56C (133F), 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).

    Intake door control system
    System Diagram System Description The intake doors are automatically controlled by the temperature setting, ambient temperature, in-vehicle temperature, intake temperature, amount of sunload ...

    Magnet clutch control system
    System Diagram System Description The A/C auto amp. controls compressor operation by ambient temperature, intake air temperature and signal from ECM. SYSTEM OPERATION When the A/C switch, t ...

    Other materials:

    ECU diagnosis information
    BCM (BODY CONTROL MODULE) Reference Value NOTE: The Signal Tech II Tool (J-50190) can be used to perform the following functions. Refer to the Signal Tech II User Guide for additional information.  Activate and display TPMS transmitter IDs  Display tire pressure reported by the ...

    Map lights
    To turn the map lights on, push the switches. To turn them off, push the switches again. CAUTION Do not use for extended periods of time with the engine stopped. This could result in a discharged battery. Personal lights To turn the rear personal lights on, push the switch. To turn the ...

    Precaution
    Precaution for Supplemental Restraint System (SRS) "AIR BAG" and "SEAT BELTPRE-TENSIONER" The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT PRE-TENSIONER”, used alongwith a front seat belt, helps to reduce the risk or severity of injury to the driver and front passeng ...

    Nissan Maxima Owners Manual

    Nissan Maxima Service and Repair Manual

    © 2017-2025 Copyright www.nimainfo.com
    0.0142