Climate Control Unit Description

• The climate control unit controls air mixture, air intake, air flow mode and fan speed.
• The following heater and A/C related functions are controlled by the PCM:
  • A/C relay (A/C relay controls A/C compressor magnetic clutch.)
  • Condenser fan
  • Idle-up control (compensates for A/C compressor and blower motor load)
    Fig 1: Identifying Climate Control Unit Features

    Courtesy of MAZDA MOTORS CORP.

Defroster control operation 

• The defroster control starts when the DEFROSTER or HEAT/DEF switch is turned on. When the defroster control starts, air intake mode and A/C ON/OFF are controlled based on the input signal of each switch.
• The transition of air intake mode and A/C ON/OFF when the defroster control operates is as shown in Fig 2 .
  Fig 2: Climate Control System Operational Flow Chart

  Courtesy of MAZDA MOTORS CORP.

Idle-up control operation 

• Engine speed is controlled via the PCM to prevent poor engine performance caused by the A/C compressor and blower motor operation (increased electrical load) while the engine is idling.
• The climate control unit sends A/C and electrical load idle-up signals to the PCM. Based on these signals, the PCM actuates the idle-up device.
  Fig 3: Identifying Idle-Up Input & Control Components

  Courtesy of MAZDA MOTORS CORP.

A/C compressor idle-up control 

• The climate control unit sends A/C signals to the PCM which actuates the A/C relay and the idle-up device.

Electrical load idle-up control 

• When the fan switch is at 3 and 4, the fan switch sends an electrical load idle-up signal to the PCM. Based on this signal, the PCM actuates the idle-up device.