55-1

GROUP 55

HEATER, AIR
CONDITIONING AND
VENTILATION
CONTENTS
GENERAL DESCRIPTION. . . . . . . . .

55-2

HEATER AND AIR CONDITIONING

SYSTEM . . . . . . . . . . . . . . . . . . . . . . .

55-4

HEATER CONTROL . . . . . . . . . . . . .
A/C-ECU. . . . . . . . . . . . . . . . . . . . . . .

A/C COMPRESSOR . . . . . . . . . . . . . .

55-9

CONDENSER . . . . . . . . . . . . . . . . . . .

55-9

DUCT. . . . . . . . . . . . . . . . . . . . . . . . . .

55-10

VENTILATION SYSTEM. . . . . . . . . . .

55-11

55-6
55-7

55-2

HEATER, AIR CONDITIONING AND VENTILATION

GENERAL DESCRIPTION

GENERAL DESCRIPTION

FEATURES

ENHANCEMENT IN SAFETY
A/C system is stopped when the air bags are
deployed.
Crushable space has been adopted to heater unit
to reduce the risk of passenger injuries in case of
a collision.

ENHANCEMENTS IN COMFORT
With the adoption of fully-automatic A/C, the outside/inside air circulation switching, air outlet, and
outlet air temperature are automatically controlled according to the ambient temperature,
solar radiation, and passenger compartment temperature so that the optimum air conditioner is
achieved. <Automatic A/C>
By the adoption of clean air filter, the air quality
inside the passenger compartment has been
enhanced.

GLOBAL ENVIRONMENT PROTECTION

New refrigerant system (HFC134a) has been
adopted.
By the optimisation of A/C system, the refrigerant
charging amount has been reduced.
Clean air filter media and its cover are separated
to reduce waste materials.

ENHANCEMENTS IN OPERATION
PERFORMANCE
Operability has been enhanced by the adoption
of large triple dial.
Customise function has been added for the
enhanced convenience.

ENHANCEMENTS IN SERVICE QUALITY

Reduction of refrigerant gas leakage and
enhancement in serviceability by incorporating
condenser and receiver
Clean air filter is installed to the backside of glove
box to facilitate the filter replacement.

ENHANCEMENTS IN FUEL ECONOMY

The high efficiency compressor with a 2-step profile oil separator has been installed, thus enhancing the fuel economy.
The idle-up speed is controlled in two steps to
secure the air cooling performance during summer and to enhance the fuel economy in the seasons with moderate temperature.

ENHANCEMENTS IN RESPONSIBILITY
Reliable information transmission is achieved by
connecting A/C-ECU and each ECU via CAN communication.

SPECIFICATIONS
ITEM

SPECIFICATION

Air conditioning switch type

Rotary type

Compressor type

MSC90CAS

Cooling output

5.5 kw

Heating output

5.7 kw

Refrigerant

M2551001500040

Enhancement of fuel economy by the cooling fan

control depending on the refrigerant pressure and
vehicle speed.

The blower, heater, and evaporator have been integrated with the heater and A/C system to achieve a
greater fan power and noise reduction.

Type

R134a (HFC-134a)

Charge quantity g (oz.)

480 - 520 (16.9 - 18.3)

55-3

HEATER, AIR CONDITIONING AND VENTILATION

GENERAL DESCRIPTION

CONSTRUCTION DIAGRAM
<AUTOMATIC AIR CONDITIONING>

Interior temperature
sensor

AC608755AC

<AUTOMATIC AIR CONDITIONING>

Ambient air temperature sensor

Photo sensor
AC608756AC

AC608760AB

Low-pressure side valve

High-pressure
side valve Suction
flexible hose
Heater unit

Liquid pipe

A/C pressure sensor

Discharge
flexible hose
A/C compressor

Condenser
AC607816AB

55-4

HEATER, AIR CONDITIONING AND VENTILATION

HEATER AND AIR CONDITIONING SYSTEM
Mode selection
damper control motor
Outside / inside air selection
damper control motor

Intake duct
Air thermo sensor

Power transistor

Blower case

Air mixing damper control

motor

A/C-ECU

Blower motor

AC607858AB

HEATER AND AIR CONDITIONING SYSTEM

M2551001000614

HEATER UNIT ASSEMBLY

Heater unit
Mode selection damper
Evaporator

Intake duct

Air mixing damper

Outside / inside air

selection damper

Blower case
Heater core

Clean air filter

AC607857AB

55-5

HEATER, AIR CONDITIONING AND VENTILATION

HEATER AND AIR CONDITIONING SYSTEM

The following new unit integrated blower, heater and

evaporator to increase the air flow, reduce noise, and
enhanced cooler and heater performance;:
Integrated heater/cooling unit has been adopted
for large air flows and low noise.
Crushable space has been secured to reduce the
risk of passenger injuries.
Air mix damper that is also used as a reheating
prevention damper has been adopted to enhance
the air cooling performance.
The A/C condensate water outlet (drain port) has
been installed to behind the evaporator to
restrain the clogging of drain by foreign materials.
The outlet air temperature of the defroster has
been set lower than that of foot to prevent overheating the drivers face.

Fin thermo sensor to directly measure evaporator

temperature reduces occurrence risk of an evaporator freeze which will lead to the compressor
lock.
Clean air filter has been introduced as standard
to protect the unit from the intrusion of foreign
materials (fallen leaves and others). and, it
removes the pollen and dust, and enhances the
air quality inside the passenger compartment.
Clean air filter media and cover have been separated to reduce the waste material amount generated during the filter replacement.
The installation position of clean air filter has
been set to the backside of glove box to facilitate
the filter replacement operation. And, the
one-touch tab structure has been adopted for the
cover installation to enable the replacement operation without tools.

OPERATION
CRUSHABLE SPACE
Front defroster
Side defroster

Side defroster

Side
outlet

Crushable space

Center
outlet

Recirculation

Crushable space

Fresh
Side
outlet
Heater core

Front side

Clean air filter

Heater outlet
Blower motor
Evaporator
.

Heater outlet
to compartment
AC506490AB

Evaporator
Drain port

Heater core
AC506491AB

The evaporator and heater core has been longitudinally installed in the vehicle length, and the crushable space has been adopted so that the structure
absorbs the impact in case of a collision and reduces
the risk of passenger injuries.

55-6

HEATER, AIR CONDITIONING AND VENTILATION

HEATER CONTROL

HEATER CONTROL

M2551000900421

HEATER CONTROLLER
.

<MANUAL A/C>
<Vehicles for USA>
Outside/Inside air
selection switch

<Vehicles for CANADA>

Rear window defogger switch

A/C switch

Outside/Inside air
selection switch

A/C switch

AC608071

Maximum
A/C position

AC608070

Blower knob

Mode selection knob

Temperature adjustment knob

<AUTOMATIC A/C>
<Vehicles for USA>
Outside/Inside air
selection switch

Rear window
defogger switch

Temperature
adjustment knob

Blower knob
Mode selection knob

<Vehicles for CANADA>

Rear window defogger switch

A/C switch

Outside/Inside air
selection switch

A/C switch

AC608068

AC608069

Blower knob
Temperature adjustment knob

Mode selection knob

Rear window
defogger switch

Temperature
adjustment knob

Blower knob
Mode selection knob

AC608329AB

The features of the heater controller described below

have been designed for better appearance, easier
operation, and enhanced visibility.
Each dial for the air outlet switching, fan volume
control, and temperature adjustment has been
enlarged to enhance operability.
Ring lights have been adopted to inside the dials
to enhance appearance during nighttime. <Vehicles with automatic A/C>

AUTO and OFF positions of the fan volume control dial have been exchenged with one another.
This change prevents the dial to pass the AUTO
position when the fan volume control is turned
OFF, and eliminates the necessity of manual
reselection when switching the inside/outside air
selection manually, thus enhancing the operability. <Vehicles with automatic A/C>
When the air outlet switching dial and fan volume
control dial are turned to the AUTO position, the
A/C switch has been made to automatically turn
ON to enhance convenience. (Using the customize function, this function can be cancelled. Refer
to P.55-7.) <Vehicles with automatic A/C>

55-7

HEATER, AIR CONDITIONING AND VENTILATION

A/C-ECU

A/C-ECU
CONTROL
.

FORCED DEF CONTROL

When air outlet position is switched to DEF, A/C is
automatically turned ON, and outside/inside air
selection damper is set to the fresh air position to
quickly defrost the windshield screen.
.

MAX A/C CONTROL <MANUAL A/C>

When the temperature adjustment knob is turned to
the maximum A/C position with the blower knob at
position other than OFF, the following controls are
made by the A/C-ECU.
Subject to control

MAX COOL

Air mix damper

MAX COOL position

Air outlet mode

Selected position

Air volume

Selected position

Outside/inside air
selection damper

Air recirculation position*

Air conditioner switch ON*

NOTE: "*" Manual operation is disabled during max
A/C control.
.

MAX COOL, MAX HOT CONTROL

<AUTOMATIC A/C>
When the set temperature is at 18.0 C <61 F>
(MAX COOL) or at 32.0 C <89 F> (MAX HOT) with
the air outlet and air volume at the AUTO positions,
the following controls are made automatically by the
A/C-ECU.
Subject to
control

MAX COOL

MAX HOT

Air mix
damper

MAX COOL
position

MAX HOT
position

Air outlet
mode

FACE position

FOOT position

Air volume

Maximum

Maximum

Outside/insid Air recirculation

e air
position*
selection
damper

Fresh air
position*

Air
conditioner
switch

OFF*

ON*

M2551001200265

NOTE: "*" indicates that when the automatic control

is not cancelled using the customise function, the
manual operation is disabled.
.

REAR WINDOW DEFOGGER TIMER

CONTROL
In order to prevent battery consumption, the defogger is automatically turned OFF, 20 minutes after it is
turned ON.
.

IDLE-UP CONTROL
A/C-ECU and the engine ECU communicate with
each other through the CAN communication. The
idle-up speed of the engine is controlled in two steps
depending on the A/C load to secure the air cooling
performance during summer and to enhance fuel
economy in seasons with moderate temperature.
.

DETECTION CONTROL FOR

REFRIGERANT LEAKS
A/C-ECU determines if the refrigerant amount is less
than specified or refrigerant pressure is abnormal by
using the ambient temperature (ambient temperature
sensor to measure refrigerant inflation rate) and
refrigerant pressure (measured by the A/C pressure
sensor). When refrigerant amount or refrigerant pressure is judged abnormal, the compressor is cut-off to
protect the A/C system.
NOTE: When abnormality occurs, the A/C indicator
flashes.
.

PROTECTION CONTROL AT AIR BAG

DEPLOYMENT (DURING COLLISION)
When the air bag deployment is detected, the A/C
system is stopped.
.

CUSTOMISE FUNCTION
Depending on the user's preference, the following
functions can be selected. The programmed information is held even when the battery is disconnected.
Automatic control for inside/outside air selection
Press and hold (approximately for 10 seconds)
the inside/outside air selection switch to cancel
the automatic control for inside/outside air selection.
A/C automatic control
Press and hold (approximately for 10 seconds)
the A/C switch to cancel the A/C automatic control.

55-8

HEATER, AIR CONDITIONING AND VENTILATION

A/C-ECU

COMMUNICATION
CAN communication

SERIAL communication
SRS-ECU

Engine-ECU

Heater control panel

A/C-ECU

ETACS-ECU

Combination meter
: Interactive communication
AC506202AC

A/C-ECU performs the signal transmission and

reception with each ECU via CAN (Controller Area
Network)*1. Also, with the heater control panel, it
transmits and receives signals via serial communication.

NOTE: : For details of CAN communication, refer to

GROUP 54C Controller Area Network P.54C-2.

CAN COMMUNICATION INPUT SIGNALS TABLE

Signal

Transmitter ECU

Engine coolant temperature signal

ENGINE-ECU

Vehicle speed signal

Engine speed signal
Ambient temperature signal

ETACS-ECU

Wiper signal
Ignition key signal
Average ambient temperature signal

DIAGNOSTIC FUNCTION
A/C-ECU has the following functions for easier system checks.
DIAGNOSTIC FUNCTION

COMBINATION METER
Service data output
Actuator test
NOTE: For each item, refer to the Workshop Manual.

HEATER, AIR CONDITIONING AND VENTILATION

A/C COMPRESSOR

A/C COMPRESSOR

55-9
M2551001100268

HIGH EFFICIENCY COMPRESSOR WITH

INTEGRATED OIL SEPARATOR

MAGNETIC CLUTCH WITH THERMAL

FUSE

High efficiency compressor with integrated oil separator has been adopted to enhance fuel economy by
reducing the A/C operating rate.

At the compressor lock, the thermal fuse integrated

in the magnet clutch is blown due to the frictional
heat against the compressor in order to reduce risk
of the drive belt breakage. The thermal fuse, together
with the coil, is coated with resin to enhance resistance to corrosion.

2-STEP PROFILE COMPRESSOR

The centre area of the scroll in the compressor provides 2-step profile, and thickness of area "B" shown
in the figure has been increased to enhance
strength. With this feature, thickness of area "A"
shown where lesser load is applied is reduced, thus
compressor performance is enhanced by compressing refrigerant even in central area, comparing to the
previous model.

<2-step profile
compressor>
<Previous model>
Front
view
Front view
Section b - b
Section a - a
A
a

AC507301AC

CONDENSER

M2551001400140

The condenser has been integrated with the radiator (cooling

module) to optimise ventilation and reduce weight.

Condenser
Radiator

AC608768AB

55-10

HEATER, AIR CONDITIONING AND VENTILATION

DUCT

DUCT

M2551001300358

To windshield (Defroster)

To front door window

(Side defroster)
Side ventilator
Center ventilator
Side ventilator

To front door window

(Side defroster)

To driver seat footwell

To passenger seat footwell

To rear seat footwell

(Vehicle with rear duct)
To rear seat footwell
(Vehicle with rear duct)
AC608058 AB

The rear heater duct has been introduced, and the

air distribution ratio to front and rear seats has been
optimised in order to enhance the air heating performance for the rear seats, and to prevent the circulation of cooled air back to the front seats. <Vehicles
with rear duct>

HEATER, AIR CONDITIONING AND VENTILATION

VENTILATION SYSTEM

VENTILATION SYSTEM

Rear ventilator duct

Fresh air is sucked from the front deck and

exhausted through the air outlet behind the rear
bumper. Optimizing areas of the outside air induction
hole and the air outlet enhances ventilated air
amount, reducing noise.

55-11
M2551002000554

AC608060 AB

NOTES