Mazda 6. Manual - part 386

U–48

CONTROL SYSTEM 

1C

Blower motor 
control signal

Power MOS FET

Fan switch is OFF

Below 1.0

• Inspect terminal voltage of 

climate control unit (1A)

Fan switch is at manual 
LO

4.1

Fan switch is at manual 
HI

7.9

1D

—

—

—

—

—

1E

Rear window 
defroster SW 
signal

Rear window 
defroster relay

Rear window defroster 
switch is off

12

• Inspect for continuity or 

short circuit (Climate control 
unit—rear window defroster 
relay: 1E—E)

• Inspect rear window 

defroster relay

Rear window defroster 
switch is on

Below 1.0

• Inspect terminal voltage of 

climate control unit (1H, 1L)

• Inspect audio switch panel

1F

On-board 
diagnostic signal

A/C check 
connector

Terminal A of A/C check 
connector is shorted.

Below 1.0

• Inspect for continuity 

(Climate control unit—A/C 
check connector: 1F—A)

Other

5.4

• Inspect short circuit (Climate 

control unit—A/C check 
connector: 1F—A)

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1G

—

—

—

—

—

1H

—

—

—

—

—

1I

GND

• Cabin 

temperature 
sensor

• Evaporator 

temperature 
sensor

• Ambient 

temperature 
sensor

• Water 

temperature 
sensor

• Air mix actuator

• Airflow mode 

actuator

Under any condition

Below 1.0

• Inspect terminal voltage of 

climate control unit (2L)

1J

—

—

—

—

—

1K

Ambient 
temperature 
sensor input

Ambient 
temperature sensor

Depends on temperature 
surrounding sensor

See  Figure 

2

• Inspect for continuity 

(Climate control unit— 
ambient temperature 
sensor: 1K—B, 1I—A)

• Inspect for short circuit 

(Climate control unit— 
ambient temperature 
sensor: 1K—B)

• Inspect ambient 

temperature sensor

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1L

—

—

—

—

—

1M

Cabin 
temperature 
sensor input

Cabin temperature 
sensor

Depends on temperature 
surrounding sensor

See  Figure 

3

• Inspect for continuity 

(Climate control unit— cabin 
temperature sensor: 1M—B, 
1I—A)

• Inspect for short circuit 

(Climate control unit— cabin 
temperature sensor: 1M—B)

• Inspect cabin temperature 

sensor

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1N

—

—

—

—

—

Terminal

Signal

Connected to 

Test condition

Voltage (V)

Action

CONTROL SYSTEM 

U–49

U

1O

Water 
temperature 
sensor input

Water temperature 
sensor

Depends on temperature 
surrounding sensor

See  Figure 

4

• Inspect for continuity 

(Climate control unit—water 
temperature sensor: 1O—A, 
1I—B)

• Inspect for short circuit 

(Climate control unit—water 
temperature sensor: 1O—A)

• Inspect water temperature 

sensor

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1P

A/C Refrigerant 

pressure switch

Fan switch at OFF

12

• Inspect for continuity or 

short circuit (Climate control 
unit—refrigerant pressure 
switch: 1P—A (Dual-
pressure type), 1P—C 
(Triple-pressure type)) 
(Refrigerant pressure 
switch—PCM: B—1AC)

• Inspect refrigerant pressure 

switch

• Inspect PCM terminal 

voltage (1AC)
(See 

F–45 PCM 

INSPECTION

 )

Fan switch at 1st 
position, A/C switch ON

Below 1.0

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1Q

Evaporator 
temperature 
sensor input 
signal

Evaporator 
temperature sensor

Depends on temperature 
surrounding sensor

See  Figure 

1

• Inspect for continuity 

(Climate control unit— 
evaporator temperature 
sensor: 1Q—A, 1I—B)

• Inspect for short circuit 

(Climate control unit— 
evaporator temperature 
sensor: 1Q—A)

• Inspect evaporator 

temperature sensor

• Inspect terminal voltage of 

climate control unit (2H, 2L)

1R

—

—

—

—

—

1S

Solar radiation 
sensor input

Solar radiation 
sensor

Incandescent light (60W) 
shining on solar 
radiation sensor from 
distance of approx. 
100mm {3.9 in}

4.0

• Inspect for continuity or 

short circuit (Climate control 
unit—solar radiation sensor: 
1S—B, 1B—A)

• Inspect terminal voltage of 

climate control unit (1B)

• Inspect solar radiation 

sensor

Light to solar radiation 
sensor block

Below 1.0

1T

GND

Ground

Under any condition

Below 1.0

• Inspect for continuity 

(Climate control unit—
ground: 1T—GND)

• Inspect center panel

1U

Potentiometer 
signal

Air mix actuator

Set temperature at MAX 
COLD

0.6

• Inspect for continuity or 

short circuit (Climate control 
unit—air mix actuator: 1U—
C)

• Inspect air mix actuator

• Inspect terminal voltage of 

climate control unit (1B)

Set temperature at MAX 
HOT

4.3

1V

—

—

—

—

—

Terminal

Signal

Connected to 

Test condition

Voltage (V)

Action

U–50

CONTROL SYSTEM 

1W

Potentiometer 
signal

Airflow mode 
actuator

VENT mode

4.3

• Inspect for continuity or 

short circuit (Climate control 
unit—airflow mode actuator: 
1W—C)

• Inspect airflow mode 

actuator

• Inspect terminal voltage of 

climate control unit (1B)

BI-LEVEL mode

3.3

HEAT mode

2.3

HEAT/DEF mode

1.5

DEFROSTER mode

0.6

1X

Hazard warning 
SW signal

Hazard warning 
switch

Hazard warning switch is 
off

12

• Inspect for continuity or 

short circuit (Climate control 
unit—flasher unit: 1X—H)

• Inspect flasher unit

Hazard warning switch is 
on

Below 1.0

• Inspect terminal voltage of 

climate control unit (1T)

• Inspect center panel

2A

Panel light control 
signal

Panel light control 
switch

Headlight switch ON and 
panel light control switch 
at max. illumination

0.2

• Inspect for continuity 

(Climate control unit— panel 
light control switch: 2A—C) 
(Panel light control switch—
ground: C—GND)

• Inspect panel light control 

switch

Headlight switch ON and 
panel light control switch 
at min. illumination

10.2

• Inspect for short circuit 

(Climate control unit— panel 
light control switch: 2A—C)

2B

TNS signal

TNS relay

Headlight switch OFF

Below 1.0

• Inspect for short circuit 

(Climate control unit—TNS 
relay: 2B—D)

• Inspect TNS relay

• Inspect headlight switch

Headlight switch ON

12

• Inspect for continuity or 

short circuit (Climate control 
unit—TNS relay: 2B—D)

• Inspect TNS relay

• Inspect headlight switch

2C

Motor drive signal

Air mix actuator

Moving to COLD

12

• Inspect for continuity or 

short circuit (Climate control 
unit—air mix actuator: 2D—
D, 2C—F)

• Inspect air mix actuator

Moving to HOT

Below 1.0

2D

Motor drive signal

Air mix actuator

Moving to HOT

12

• Inspect for continuity or 

short circuit (Climate control 
unit—air mix actuator: 2C—
F, 2D—D)

• Inspect air mix actuator

Moving to COLD

Below 1.0

2E

Motor drive signal

Airflow mode 
actuator

Moving to DEFROSTER

12

• Inspect for continuity or 

short circuit (Climate control 
unit—airflow mode actuator: 
2E—F, 2G—D)

• Inspect airflow mode 

actuator

Moving to VENT

Below 1.0

2F

Backup power 
supply

 ROOM 15 A fuse

Under any condition

B+

• Inspect for continuity or 

short circuit (Climate control 
unit—fuse: 2F— ROOM 15 
A fuse)

• Inspect ROOM 15 A fuse

2G

Motor drive signal

Airflow mode 
actuator

Moving to VENT

12

• Inspect for continuity or 

short circuit (Climate control 
unit—airflow mode actuator: 
2G—D, 2E—F)

• Inspect airflow mode 

actuator

Moving to DEFROSTER

Below 1.0

Terminal

Signal

Connected to 

Test condition

Voltage (V)

Action

CONTROL SYSTEM 

U–51

U

End Of Sie

2H

IG2

A/C 15 A fuse

Ignition switch at ON 
position

B+

• Inspect for continuity or 

short circuit (Climate control 
unit—fuse: 2H—A/C 15 A 
fuse)

• Inspect A/C 15 A fuse

Ignition switch at LOCK 
position

Below 1.0

• Inspect for short circuit 

(Climate control unit—fuse: 
2H—A/C 15 A fuse)

2I

Motor drive signal

Air intake actuator

Moving to 
RECIRCULATE

12

• Inspect for continuity or 

short circuit (Climate control 
unit—air intake actuator: 
2I—F, 2K—D)

• Inspect air intake actuator

Moving to FRESH

Below 1.0

2J

—

—

—

—

—

2K

Motor drive signal

Air intake actuator

Moving to FRESH

12

• Inspect for continuity or 

short circuit (Climate control 
unit—air intake actuator: 
2K—D, 2I—F)

• Inspect air intake actuator

Moving to 
RECIRCULATE

Below 1.0

2L

GND

Ground

Under any condition

Below 1.0

• Inspect for continuity 

(Climate control unit—
ground: 2L—GND)

Terminal

Signal

Connected to 

Test condition

Voltage (V)

Action