2001 TOYOTA PRIUS Service Repair Manual

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
163BE17
Inner FinAntibacterial Agent
Nylon Layer
Chromate Layer
Aluminum
Matrix
182BE48
ModulatorMulti-Flow Condenser
Condensing Portion
Gaseous Refrigerant
Liquid Refrigerant
Super-Cooling Portion 158
Evaporator
By placing the tanks at the top and the bottom of the evaporator unit and by adopting an inner fin construc-
tion, the heat exchanging efficiency has been improved and the evaporator unit's temperature distribution
has been made more uniform. As a result, it has become possible to realize a thinner evaporator construction.
Furthermore, the evaporator body has been coated with a type of resin that contains an antibacterial agent
in order to minimize the source of foul odor and the propagation of bacteria.
2. Condenser
The Prius has adopted sub-cool condenser in which a multi-flow condenser (consisting of two cooling por-
tions: a condensing portion and a super-cooling portion) and a gas-liquid separator (modulator) have been
integrated. This condenser has adopted the sub-cool cycle for its cooling cycle system to improve the heat
exchanging efficiency.
This condenser is integrated with the radiator to minimize the space they occupy in the engine compartment.
For details, see page 54 in the Engine Cooling System Section.
Sub-Cool Cycle
In the sub-cool cycle of the sub-cool condenser that has been adopted, after the refrigerant passes through
the condensing portion of the condenser, both the liquid refrigerant and the gaseous refrigerant that could
not be liquefied are cooled again in the super-cooling portion. Thus, the refrigerant is sent to the evaporator
in an almost completely liquefied state.

BODY ELECTRICAL ± AIR CONDITIONING
152BE40
High Pressure
Properly Recharged Amount
Point in which Bubbles Disappear
Amount of Refrigerant159
NOTE:The point at which the air bubbles disappear in the refrigerant of the sub-cool cycle is lower than the
proper amount of refrigerant with which the system must be filled. Therefore, if the system is recharged
with refrigerant based on the point at which the air bubbles disappear, the amount of refrigerant would
be insufficient. As a result, the cooling performance of the system will be affected.
For the proper method of verifying the amount of the refrigerant and to recharge the system with refrig-
erant, see the 2001 Prius Repair Manual (Pub. No.RM778U).

BODY ELECTRICAL ± AIR CONDITIONING
165BE22 165BE21
Fixed Scroll Magnetic
ClutchShaft Suction Port
Oil Separator
Discharge Port
Fixed Scroll Variable Scroll PinsDischarge PortIntake Port 160
3. Compressor
General
A compact and high performance scroll compressor with oil separator has been adopted.
Construction
The scroll compressor with oil separator consists of a spirally wound fixed scroll and variable scroll that
form a pair, and oil separator, and a magnetic clutch.
The fixed scroll is integrated with the housing. Because the rotation of the shaft causes the variable scroll
to revolve while maintaining the same posture, the volume of the space that is partitioned by both scrolls
varies to perform the suction, compression, and the discharge of the refrigerant gas.
A pin is attached behind the variable scroll to prevent the autorotation of the variable scroll, allowing it only
to revolve.
Locating the suction port directly above the scrolls enables direct suction, thus realizing improved suction
efficiency.
Containing a built-in oil separator, this compressor is able to separate the compressor oil that is intermixed
with the refrigerant and circulates in the refrigeration cycle, thus realizing a reduction in the oil circulation
rate.