Mazda Training manual — part 290

AIR CONDITIONING
SG02 - Control System [Manual Air Conditioning]

SG02-11

TC070-15-01H

Refrigerant pressure switch

The figure below shows a triple pressure type refrigerant pressure switch that
consists of the low/high-pressure switch and the medium-pressure switch. The
low/high-pressure switch protects the refrigerant cycle by cutting the A/C signal when
pressure in the refrigerant cycle is either abnormally high or low. The medium-
pressure switch outputs an idling increase signal according to the A/C compressor
operation load.

Why do you think the system needs to cut the A/C signal when pressure in the
refrigerant cycle is abnormally low? How does it affect the system?






Medium-pressure switch operates when the refrigerant pressure is approx. 1.52 kPa
{14.2 kgf·cm2, 202 psi} or more. When it operates, the contact is closed to send an
“Idling increase signal” to the PCM. When the A/C is on and an Idling increase signal
is input to the PCM, it sends an operation signal to the IAC solenoid valve.

AIR CONDITIONING
SG02 - Control System [Manual Air Conditioning]

SG02-12

TC070-15-01H

Fan switch

The diagram of fan switch is shown in the figure below. Its function can be verified by
checking the continuity between the terminals at a given status of switch position as
shown in the table below.

Climate control unit

A wire-type climate control unit is used with the manual air conditioner.

1. Airflow mode wire
2. Air mix wire
3. Air intake wire
4. Illumination bulb
5. Dial
6. Knob
7. Fan switch
8. Body

AIR CONDITIONING
SG02 - Control System [Manual Air Conditioning]

SG02-13

TC070-15-01H

The airflow mode selector dial, temperature control dial, airflow volume control dial
have been enlarged to improve ease of operation.

1. Climate control unit
2. Airflow mode selector dial
3. Airflow volume control dial
4. Temperature control dial
5. A/C switch
6. REC/FRESH switch
7. Rear window defroster switch

Block Diagram

The climate control unit sends an A/C signal to the PCM via the main fuse and
instrument cluster (PJB and instrument cluster) based on signals sent from the A/C
switch, fan switch and evaporator temperature sensor.
The PCM sends operating signals to the A/C relay and IAC valve based on A/C
signal and vehicle signal.

AIR CONDITIONING
SG02 - Control System [Manual Air Conditioning]

SG02-14

TC070-15-01H

Outline of Control System

Manual air conditioner defroster control and A/C compressor control.

Defroster Control

1. When the airflow mode selector dial is turned to DEFROSTER position, a wire

moves the airflow mode main link, turning the airflow mode to DEFROSTER.

2. The defroster switch turns on at the same time, and the CPU sends a signal to turn

the air intake mode to FRESH.

3. The air intake actuator operates and turns the air intake mode to FRESH.

1. Climate control unit
2. Airflow mode selector
dial
3. To DEFROSTER
position
4. Defroster switch
5. Wire
6. Airflow mode main link
7. FRESH signal
8. Air intake actuator
9. To FRESH position