AIR CONDITIONING SYSTEM DETAILS

Electric Inverter Compressor Control

1. The air conditioning amplifier assembly calculates the target compressor speed based on the target evaporator temperature (calculated from the temperature control switch, room temperature sensor, ambient temperature sensor, and automatic light control sensor) and the actual evaporator temperature detected by the evaporator temperature sensor. Then, the air conditioning amplifier assembly transmits the target speed to the power management control ECU. The power management control ECU controls the A/C inverter based on the target speed data in order to control the electric inverter compressor to a speed that suits the operating condition of the air conditioning system.

2. The air conditioning amplifier assembly calculates the target evaporator temperature, which includes corrections based on the temperature control switch, room temperature sensor, ambient temperature sensor, automatic light control sensor, and evaporator temperature sensor. Accordingly, the air conditioning amplifier assembly controls the compressor speed to an extent that does not inhibit the proper cooling performance or defogging performance. As a result, comfort and low fuel consumption can be realized.

3. The electric inverter compressor uses high-voltage alternating current. If a short or open circuit occurs in the electric inverter compressor wiring harness, the power management control ECU will cut off the A/C inverter circuit in order to stop the power supply to the compressor motor.

   

Solar Ventilation System Control

1. If the ventilation switch is turned on when the power switch is turned to ON (IG):

   
   

   • In order to provide more efficient ventilation, the air conditioning amplifier assembly switches the air inlet port to the FRESH mode and the air outlet port to the FACE mode after approximately 1 minute has passed since the power switch was turned off.

   • In order to prevent cold air in the cabin escaping outside immediately after the engine is stopped, the solar ECU activates the blower motor to start ventilation after approximately 10 minutes have passed since the power switch was turned off.

   

2. If the ventilation switch is turned on when the power switch is turned to off:

   
   

   • The air inlet and outlet modes remain the same and the solar ECU starts ventilation approximately 10 minutes after the ventilation switch is turned on.

   

   Tech Tips

   If the solar ventilation system is used because the ventilating effect cannot be obtained sufficiently in the internal air mode, turn on the ventilation switch when the power switch is turned to on (IG).

Remote Air Conditioning System Control

1. The remote air conditioning system can be activated by pressing and holding the remote air conditioning switch on the wireless key once (for approximately 1 second or more). At this time, the wireless door lock will also be activated, thus improving anti-theft performance.

2. The remote air conditioning system can be deactivated by pushing the remote air conditioning switch on the wireless key twice briefly (for approximately less than 3 seconds) while the remote air conditioning system is in operation. At this time, the wireless door lock buzzer will sound twice as an answer back on Australian models only.

   

   Step	System Operation
   (1)	Sends the remote control system activation signal from the remote air conditioning switch on the wireless key to the main body ECU via the certification ECU.
   (2)	The main body ECU checks the operating condition and sends the remote air conditioning on request signal to the power management control ECU.
   (3)	The power management control ECU turns the IG1 and IG2 relays on according to the remote air conditioning on request signal.
   (4)	The main body ECU sends the HV system starting request signal to the power management control ECU.
   (5)	The power management control ECU checks the operating condition, turns on the system main relay and then operates the w/converter Inverter assembly.
   (6)	The main body ECU sends the remote air conditioning mode signal to the air conditioning amplifier assembly.
   (7)	The air conditioning amplifier assembly checks the operating condition, drives the electric inverter compressor and the blower with fan motor sub-assembly and then activates the auto air conditioning system.

Air Conditioning Radiator Assembly

1. A semi-center location air conditioner unit in which the cooler evaporator sub-assembly and heater radiator unit sub-assembly are placed in the vehicle's longitudinal direction is used.

   

   Text in Illustration

   *1

   Cooler Evaporator Sub-assembly

   *2

   Heater Radiator Unit Sub-assembly

2. The partial recirculation system is used. This system has an air inlet control door (sub) in the cabin side of the air inlet duct. Thus, it is able to cycle a small volume of recirculated air even in the FRESH mode, thus ensuring heating and air conditioning performance. When the blower switch is on, the suction force of the blower fan opens this air inlet control door (sub).

   

   Text in Illustration

   *1	Air Inlet Control Door	*2	Fresh
   *3	Recirculation	*4	Air Inlet Duct
   *5	Air Inlet Control Door (sub)	*6	To Blower Fan

Cooler Evaporator Sub-assembly

1. The Ejector Cycle System (ECS) type cooler evaporator sub-assembly is used.

2. By placing the tanks at the top and the bottom of the evaporator unit and adopting a micropore tube construction, the following effects have been realized:

   
   

   • The heat exchanging efficiency has been improved.

   • The temperature distribution has been made more uniform.

   • The evaporator has been made thinner.

3. The ejector is provided in the top tank of the cooler evaporator sub-assembly.

   

   Text in Illustration

   *1	Top Tank (Built into the ejector)	*2	Bottom Tank
   *3	Upwind Side	*4	Downwind Side

Heater Radiator Unit Sub-assembly

1. This heater radiator unit sub-assembly has been made more compact and higher performance by making the core section finer and improving the shapes of the tank section and flow section. Also, the environment is considered. By using aluminum as the material, the amount of the environmental burden disposal (lead) is reduced.

   

Bus Connector

1. The Bus connector is used in the wire harness connection that connects the servo motor from the air conditioning amplifier assembly.

   

   Text in Illustration

   *1	Bus Connector	*2	To Mode Control Servo Motor
   *3	To Air Inlet Control Servo Motor	*4	To Air Mix Control Servo Motor
   *5	To Air Conditioning Amplifier Assembly	*6	To Evaporator Temperature Sensor

2. The Bus connector has a built-in driver IC which communicates with each servo motor connector, actuates the servo motor, and has a position detection function. This enables bus communication for the servo motor wire harness, for a more lightweight construction and a reduced number of wires.

   

Servo Motor

1. In contrast to the previous type that detects the position by way of a potentiometer voltage, the pulse pattern type servomotor detects the relative position by way of the 2-bit on/off signals.

2. The forward and reverse revolutions of this motor are detected by way of two phases, A and B, which output four types of patterns. The air conditioning amplifier assembly counts the number of pulse patterns in order to determine the stopped position.

   

PTC Heater

1. The PTC (Positive Temperature Coefficient) heater is located above the heater radiator unit sub-assembly in the air conditioner unit.

2. The PTC heater consists of a PTC element, aluminum fin, and brass plate. When current is applied to the PTC element, it generates heat to warm the air that passes through the unit.

   

   Text in Illustration

   *1	PTC Heater	*2	Aluminum Fin
   *3	Brass Plate	*4	PTC Element

Clean Air Filter

1. A pollen removal type clean air filter is used to remove dust, pollen, and other micron particles from air entering from outside the vehicle to provide a comfortable cabin of clean air. The clean air filter is installed in the upper section of the blower fan for easy replacement of the clean air filter without the need for tools by removing the one-touch clip in the glove box, making this easy to service.

   

   Text in Illustration

   *1	Clean Air Filter	*2	Large Foreign Object Filter Layer
   *3	Electret Layer (Microscopic foreign object)	-	-

   Tech Tips

   The following table describes the usage conditions and cleaning and replacement intervals for models equipped with the solar ventilation system. However, the observation of these guidelines should depend on the usage conditions (or environment).

   Destination	Usage Conditions and Solar Ventilation System Setting	Cleaning Interval	Replacement Interval
   Europe models	Normal condition	15000 km (9000mile)	30000 km (18000mile)
   	Dusty road conditions or models equipped with solar ventilation system	7500 km (4500mile)	15000 km (9000mile)
   Australia model	Normal condition	15000 km (9000mile)	30000 km (18000mile)
   	Dusty road conditions or models equipped with the solar ventilation	7500 km (4500mile)	15000 km (9000mile)

W/receiver Condenser Assembly

1. A MF (Multi-Flow) type w/receiver condenser assembly is used. The w/receiver condenser assembly consists of two cooling portions: a condensing portion and a super-cooling portion, and gas-liquid separator (modulator) are integrated together. This w/receiver condenser assembly uses a sub-cool cycle that offers excellent heat-exchange performance.

2. In the sub-cool cycle, after the refrigerant passes through the condensing portion of the w/receiver condenser assembly, 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 cooler evaporator sub-assembly in an almost completely liquefied state.

   

   Text in Illustration

   *1	Desiccant	*2	Filter
   *3	Modulator	*4	Condensing Portion
   *5	Super-cooling Portion	*6	Gaseous Refrigerant
   *7	Liquid Refrigerant	-	-

   Tech Tips

   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 would be affected. If the system is overcharged with refrigerant, this will also lead to reduced performance. For the proper method of verifying the amount of the refrigerant and for instructions on how to recharge the system with refrigerant, see the Repair Manual.

   

Electric Inverter Compressor

1. An ES14 type electric inverter compressor that is driven by a motor is used. The basic construction and operation of this compressor are the same as the ordinary scroll compressor, except that it is driven by an electric motor.

2. The compressor with motor assembly consists of a spirally wound fixed scroll and variable scroll that form a pair, a brushless motor, an oil separator, a motor shaft and A/C (Air Conditioning) inverter.

3. The A/C inverter is integrated with the compressor. This inverter operates the compressor on the HV battery. As a result, the air conditioning system is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.

4. 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. 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.

5. Low-moisture permeation hoses are used for the suction and discharge hoses at the compressor in order to minimize the entry of moisture into the refrigeration cycle.

   

   Text in Illustration

   *1	Variable Scroll	*2	Fixed Scroll
   *3	Oil Separator	*4	Discharge Port
   *5	Brushless Motor	*6	Motor Shaft
   *7	A/C Inverter	*8	Discharge Hose Port
   *9	Suction Hose Port	-	-

   CAUTION:

   In order ensure the proper insulation of the internal high-voltage portion of the compressor and the compressor housing, the new Prius has adopted a compressor oil (ND11) with a high level of insulation performance. Therefore, never use a compressor oil other than the ND11 type compressor oil or its equivalent.

Mode Position and Door Operation

Control Damper	Operation Position		Damper Position	Operation
Mode Control Damper		FACE	E, J	Air blows out of the center register and side register.
		BI-LEVEL	F, J	Air blows out of the center register, side registers, and front and rear footwell register ducts.
		FOOT	F, I	Air blows out of the front and rear footwell register ducts and side register. In addition, air blows out slightly from the front defroster and side defroster.
		FOOT/DEF	F, H	Defrosts the windshield through the center defroster, side defroster and side register, while air is also blown out from the front and rear footwell register ducts.
		DEF	E, G	Defrosts the windshield through the center defroster, side defroster and side register.

Air Outlets and Airflow Volume

Ejector Cycle System Operation

1. In the conventional refrigerant cycle, liquid refrigerant gas is sent into the cooler evaporator sub-assembly using the cooler expansion valve, generating cold air. However, a rapid decrease in the refrigerant pressure forms swirls, causing energy loss. In this ejector cycle, the energy loss caused by the cooler expansion valve is utilized by the operation of the ejector that injects and expands a high-pressure refrigerant, thus improving energy consumption efficiency.

   

   

2. The ejector includes nozzle, mixing and diffuser portions.

3. A high temperature and pressure liquid refrigerant flowing from the w/receiver condenser assembly is introduced into the mixing section through the nozzle at high speeds as the nozzle is inwardly tapered. This decreases the refrigerant pressure in the vicinity of the nozzle, introducing low temperature and pressure gaseous refrigerant into the nozzle from the cooler evaporator sub-assembly. Thus, both refrigerants are mixed in the mixing section and are introduced into the diffuser section.

4. As the diffuser section is outwardly flared, the refrigerant flow rate in the diffuser decreases and the refrigerant pressure rises.

5. Through these operations, the refrigerant pressure in the cooler evaporator sub-assembly on the downwind side can be constantly kept lower than that on the upwind side, creating the lower temperature conditions. Therefore, air cooled by the cooler evaporator sub-assembly on the upwind side can be further cooled by that on the downwind side, thus improving the efficiency of the cooler evaporator sub-assembly.