2001 TOYOTA PRIUS heater

ENGINE ± 1NZ-FXE ENGINE
No.4 INJECTOR
SPARK PLUGS
No.2 INJECTOR
No.1 INJECTOR
No.3 INJECTOR SENSORS ACTUATORS
SFI
#10
CRANKSHAFT POSITION
SENSORNE
CAMSHAFT POSITION
SENSORG2
THROTTLE POSITION SENSORVTA
VTA2
COMBINATION METER
SPD

Vehicle Speed Signal
HEATED OXYGEN SENSOR
(Bank 1, Sensor 1)OX1A
HEATED OXYGEN SENSOR
(Bank 1, Sensor 2)OX1B
AMBIENT TEMP. SENSORTA M
ESA
IGT1

IGT4
IGF
THROTTLE CONTROL
MOTORETCS-i
M
ECM
ENGINE COOLANT TEMP.
SENSORTHW
INTAKE AIR TEMP. SENSORTHA
MASS AIR FLOW METERVG
IGNITION SWITCHIGSW
KNOCK SENSORKNK1
OIL PRESSURE SWITCHMOPS
CAMSHAFT TIMING OIL
CONTROL VALVE OCV
VVT-i
Bank 1, Sensor 2
Bank 1, Sensor 1HT1A
HT1B
#20
#30
#40
OXYGEN SENSOR HEATER
CONTROL
HEATED OXYGEN SENSOR
HEATER
CIRCUIT OPENING RELAYFUEL PUMP CONTROLFC
IGNITION COIL
with IGNITER
63
2. Construction
The configuration of the engine control system in the INZ-FXE engine is shown in the following chart.
(Continued)

BODY ELECTRICAL ± AIR CONDITIONING 152
AIR CONDITIONING
DESCRIPTION
The air conditioning system in the Prius has the following features:
Both heating and demisting performances are realized by adopting performances are realized by adopting
the 2-way flow heater type air conditioning unit.
A multi-tank, super-slim structure evaporator has been adopted.
An automatic air conditioning system which provides enhanced air conditioning comfort according to the
occupant's senses has been adopted.
A semi-center location air conditioning unit, in which the evaporator and heater core are placed in the ve-
hicle's longitudinal direction, has been adopted.
A compact, high-performance scroll compressor with oil separator has been adopted.
The heat exchange efficiency has been improved through the adoption of the sub-cool condenser.
This condenser is integrated with the radiator to minimize the space they occupy in the engine compart-
ment.
A compact, lightweight, and highly efficient straight flow (full-path flow) aluminium heater core has been
adopted.
This heater core is integrated with a PTC (Positive Temperature Coefficient) heater, which excels in heat-
ing performance.
PTC heaters have been provided in the air duct at the footwell outlet in front of the air conditioning unit.
However, air conditioning without the PTC heaters is offered as an option on the U.S.A. models.
An electrical water pump with a bypass valve that provides a stable heater performance even if the engine
is stopped due to a function of the THS (TOYOTA Hybrid System) has been adopted.
A clean air filter that excels in removing pollen and dust is standard equipment.

BODY ELECTRICAL ± AIR CONDITIONING
Ventilation and
Heater Air Conditioning
153

Performance 
ItemPerformance
Heat Output W5300
HeaterAir Flow Volume m3/h330
Power Consumption W170
Heater Core Inte-
grated PTC HeaterHeat Output W330 (165 x 2)
PIC Heater*1Heat Output W165 x 2
Heat Output W4200*2
Air ConditioningAir Flow Volume m3/h450g
Power Consumption W200
*1: U.S.A. Cold Area Specification Model and Canada Model
*
2: When the compressor is at 1,800 rpm

Specifications 
ItemSpecifications
TypeStraight Flow
(Full-path Flow)
Heater CoreSize
W x H x L mm (in.)216.9 x 140 x 27
(8.5 x 5.5 x 1.1)
Fin Pitch mm (in.)1.8 (0.07)
Motor TypeS70F-13T
BlowerFan SizeExternal Air132 x 41
(5.2 x 1.6)
Fan Size
Dia. x H mm (in.)Internal Air150 x 36
(5.9 x 1.4)
TypeMulti-Flow Type
(Sub-Cool Type)
CondenserSize
W x H x L mm (in.)600 x 349.8 x 37.5*
(23.6 x 13.8 x 1.5)
Fin Pitch mm (in.)2.8 (0.11)
TypeDrawn Cup
(Multi-tank, Super Slim Structure)
EvaporatorSize
W x H x L mm (in.)253.2 x 215 x 58
(10.0 x 8.5 x 2.3)
Fin Pitch mm (in.)3.5 (0.14)
CompressorTypeSCS06
*: With the radiator

BODY ELECTRICAL ± AIR CONDITIONING
182BE15
External Air
Internal AirFresh, dry external air
to the upper area
Warm internal air to
the footwell area
181BE38
Airflow During 2-way Flow Control
Internal
External
Door
Internal
AirExternal
AirInternal
AirDEF
EvaporatorFA C E
Mode Door
FOOT and Rr FOOT Heater
Core Air Mix Door
External Air
Internal Air 154
CONSTRUCTION AND OPERATION
1. Air Conditioning Unit
Air Conditioning Assembly
1) General
A semi-center location air conditioning unit, in which the multi tank type evaporator and straight flow
heater core are placed in the vehicle's longitudinal direction, has been adopted.
Both heating and demisting performances are realized by adopting the 2-way flow heater type air
conditioning unit.
This unit, which introduces external air and internal air simultaneously, discharges warm internal air
to the footwell area, and the fresh, dry external air to the upper area. Thus, it realizes both excellent
heating performance and demisting performance.
2) Construction
A partition plate divides the inside of the air conditioning unit into two parts, the external air passage,
and the internal air passage. Thus, by controlling the external air door and the internal air door separately,
the external air and internal air are introduced into the cabin in the following three modes: fresh-air mode,
recirculation mode, and fresh-air / recirculation (2-way flow) mode.

BODY ELECTRICAL ± AIR CONDITIONING
152BE22152BE21New (Straight Flow)
Previous (U-turn Flow)
165BE18
PTC Heaters
Insulation Film
PTC Element
Electrode155
3) 2-Way Flow (Fresh-air / Recirculation) Mode
When all the conditions listed below are met, the external air door, internal air door, which are controlled
by the air conditioning ECU, are switched to the 2-way flow mode.
External air mode in the selected state
Blower switch in the ON state (except OFF)
Tentative air mix damper opening angle is above the specified value. (MAX HOT)
Mode select switch in either FOOT or FOOT / DEF state
Heater Core and PTC Heater
1) General
A compact, lightweight, and highly efficient straight flow (full-path flow) aluminum heater core has
been adopted.
The 2 PTC (Positive Temperature Coefficient) heaters have been built into the heater core.

BODY ELECTRICAL ± AIR CONDITIONING
182BE17
PTC Heaters
182BE18
ALT AM1Ignition
Switch
HTR
MAIN
PS
HTR1PTC
HTR1PTC
HTR2
Battery
Heater Core
Integrated
PTC HeaterPTC Heaters
IG
HTR0
Air
Conditioning
ECU
HTR2
GNDMPX
IDH
Switch Signals from
Heater Control Panel
ECM
Body
ECU
Converter
Ambient
Temperature Sensor
Engine Coolant
Temperature Sensor
156
PTC heaters have been provided in the air
duct at the footwell outlet in front of the air
conditioning unit. However, air condition-
ing without the PTC heaters is offered as an
option on the U.S.A. models.
This PTC heater, which is a honeycomb-
shaped PTC thermistor, directly warms the
air that flows in the duct.

Wiring Diagram 

BODY ELECTRICAL ± AIR CONDITIONING157
2) Operation
a. Heater Core Integrated PTC Heater Model
The heater turns ON when all the conditions listed below have been met.
i) Outlet is in the DEF mode:
Coolant temperature is below the specified value.
Ambient temperature is below the specified value.
Converter's PTC heater prohibition signal is OFF.
ii) Outlet is in the FOOT or FOOT / DEF mode:
Coolant temperature is below the specified value.
Tentative air mix damper opening angle is above the specified value. (MAX HOT)
Converter's PTC heater prohibition signal is OFF.
b. Heater Core Integrated PTC Heater and PTC Heater Model
In the case of the heater core integrated PTC heater and PTC heater model, the conditions under which
the heater core integrated PTC heater operates are the same as those for the heater core integrated PTC
heater model described above. Furthermore, in the heater core integrated PTC heater and PTC heater
model, the PTC heater turns ON when all the conditions listed below have been met.
Outlet is in the FOOT or FOOT / DEF mode.
Blower switch in the ON state.
Coolant temperature is below the specified value.
Tentative air mix damper opening angle is above the specified value. (MAX HOT)
Converter's PTC heater prohibition signal is OFF.

BODY ELECTRICAL ± AIR CONDITIONING
165BE26165BE25
Discharge Port
Discharge Service Port
Pipe
Oil Discharge Hole
Shutter
Oil Storage Chamber
Discharge ValveRefrigerant and
Compressor OilRefrigerant
Compressor
Oil
182BE20182BE19
Flow of Coolant
Bypass Valve
Water Pump OFF
(Engine ON)Bypass Valve
Water Pump ON
(Engine OFF)Flow of Coolant163
2) Construction and Operation
The refrigerant gas that is discharged from the discharge port flows by rotating around the cylindrical
pipe in the oil separator. At this time, the centrifugal force that is created during the rotation separates
the refrigerant gas and the compressor oil due to the difference in their specific gravity. The refrigerant
gas with the lighter specific gravity passes through the inside of the pipe and travels from the discharge
service port to the outside of the compressor. The compressor oil with the heavier specific gravity is dis-
charged through the oil discharge hole in the shutter and is stored in the oil storage chamber. Then, the
compressor oil is fed again into the compressor and circulates inside the compressor.
4. Water Pump (For Air Conditioning)
An electrical water pump with a bypass valve that provides a stable heater performance even if the engine
is stopped due to a function of the THS has been adopted.
When the engine is running, this water pump ceases its operation and opens the bypass valve to minimize
the flow resistance of the coolant that is pumped by the engine water pump.