AIR CONDITIONING SYSTEM DETAILS

Compressor Speed Control

1. The air conditioning amplifier assembly calculates the target compressor speed based on the target evaporator temperature (calculated from the temperature control switch, cooler (room temperature sensor) thermistor , ambient temperature sensor (thermistor assembly), and automatic light control sensor) and the actual evaporator temperature detected by the evaporator temperature sensor (cooler thermistor No. 1). 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 compressor with motor assembly 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, cooler (room temperature sensor) thermistor, ambient temperature sensor (thermistor assembly), automatic light control sensor, and evaporator temperature sensor (cooler thermistor No. 1). Accordingly, the air conditioning amplifier assembly controls the compressor speed so that it does not inhibit proper cooling performance or defogging performance. As a result, comfort and low fuel consumption can be realized.

3. The compressor with motor assembly 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.

   

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 (electrical key transmitter sub-assembly) 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 (electrical key transmitter sub-assembly) twice briefly for less than approximately 3 seconds while the remote air conditioning system is in operation. At this time, the hazard lights will blink twice as an answer back and the wireless door lock buzzer will sound twice.

   

   Step	System Operation
   (1)	Sends the remote control system activation signal from the remote climate control system for plug-in HV button on the wireless remote key to the main body ECU (multiplex network body ECU) via the certification ECU.
   (2)	The main body ECU (multiplex network body ECU) checks the operating condition and sends the remote climate control system for plug-in HV 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 climate control system for plug-in HV on request signal.
   (4)	The main body ECU (multiplex network 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 inverter with converter assembly.
   (6)	The main body ECU (multiplex network body ECU) sends the remote climate control system for plug-in HV 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 No. 1 and heater radiator unit sub-assembly are placed in the vehicle's longitudinal direction is used.

   

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   *1

   Cooler Evaporator Sub-assembly No. 1

   *2

   Heater Radiator Unit Sub-assembly

2. A 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).

   

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   *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 No. 1

1. An Ejector Cycle System (ECS) type cooler evaporator sub-assembly No. 1 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 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 No. 1.

   

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   *1	Top Tank (Ejector built-in)	*2	Bottom Tank
   *3	Upwind Side	*4	Downwind Side

Heater Radiator Unit Sub-assembly

1. The heater radiator unit sub-assembly has been made more compact and higher performing by making the core section finer and improving the shapes of the tank section and flow section. Also, in consideration of the environment, aluminum is used as the construction material, reducing the environmental burden due to the disposal of lead.

   

Bus Connector

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

   

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   *A	LHD Models	*B	RHD Models
   *1	Bus Connector	*2	Air Conditioning Harness Assembly
   *a	To Air Conditioning Amplifier Assembly	*b	To Servo Motor

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 of servo motor that detects the position by way of a potentiometer voltage, a pulse pattern type servo motor detects the relative position by way of the 2-bit on/off signals.

2. The forward and reverse revolutions of this type of servo 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 (Quick Heater Assembly)

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

2. The PTC heater (quick heater assembly) 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.

   

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   *1	PTC Heater (Quick Heater Assembly)	*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 without the need for tools by removing the one-touch clip in the glove box.

   

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

Condenser with Receiver Assembly

1. A MF (Multi-Flow) type condenser with receiver assembly is used. The condenser with receiver assembly consists of two cooling portions: a condensing portion and a super-cooling portion, and gas-liquid separator (modulator) are integrated together. This condenser with receiver 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 condenser with receiver 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 No. 1 in an almost completely liquefied state.

   

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   *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 refrigerant and for instructions on how to recharge the system with refrigerant, see the Repair Manual.

   

Compressor with Motor Assembly

1. An ES14 type compressor with motor assembly that is driven by a motor is used. The basic construction and operation of this compressor are the same as an 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 rotating 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 using power from 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 rotating 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 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, the 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 of the compressor in order to minimize the entry of moisture into the refrigeration cycle.

   

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   *1	Rotating 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 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 a 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 reducing energy consumption.

   

   

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

3. A high temperature and pressure liquid refrigerant flowing from the condenser with receiver 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 pressurized 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 pressurized 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.