AIR CONDITIONING SYSTEM

Refrigerant Volume Detection Control

1. The air conditioning amplifier assembly judges the volume of refrigerant from the ambient temperature, refrigerant pressure and the temperature of the cool air past the No. 1 cooler evaporator sub-assembly. When the air conditioning amplifier assembly judges refrigerant shortage, it turns off the indicator light of the A/C switch. At that time, the compressor with pulley assembly stops operating.

   

PTC Heater Control

1. The on/off function of the PTC heater (quick heater assembly) is controlled by the air conditioning amplifier assembly in accordance with the engine coolant temperature, engine speed, air mix setting, and electrical load (generator power ratio).

2. For example, the number of the operating PTC heater (quick heater assembly) varies with engine coolant temperature as in the graph below.

   

   *a	Heating Value
   *b	Engine Coolant Temperature

Combustion Type Power Heater Control

1. When the engine is operating, turning the power heater switch (heater switch assembly) on causes the air fan to operate for several seconds for verification purposes. Then, the glow plug starts to preheat the combustion chamber. After that, the fuel pump and air fan turn on in order to start low combustion. The fuel pump speed is then increased in steps, and this is accompanied by a gradual increase in the speed of the air fan, thus leading to high combustion.

2. When the ignition switch is turned off or the power heater switch (heater switch assembly) is turned off, the fuel pump stops, causing the combustion to stop. For the purpose of after-purge, current is applied again to the glow plug, and the air fan is activated for several seconds. Then, the entire system comes to a stop.

   

3. While the system is in operation, it controls the fuel pump speed and switches between high combustion and low combustion, constantly keeping the engine coolant temperature between 75°C (167°F) and 85°C (185°F). If the engine coolant temperature exceeds 85°C (185°F), the fuel pump stops automatically to stop the combustion. Thereafter, when the engine coolant temperature reaches 75°C (167°F) or below, ignition occurs again. The operation of the glow plug, the air fan, and the fuel pump during extinguishing and re-igniting is the same as when these are operated by a switch as mentioned previously.

   

4. For self-protection, the combustion type power heater stops if an abnormal condition is detected. Descriptions of the function are indicated below:

   Function	Outline
   Dry Run Prevention	If the temperature detected by the engine coolant temperature sensor or the overheating prevention sensor exceeds 125°C (257°F), the power heater ECU determines that the heater is operating without water and automatically stops the system.
   Overheating Prevention	If the difference in temperature detected by the engine coolant temperature sensor and the overheating prevention sensor exceeds 25°C (77°F), the power heater ECU determines that the flow volume of the water is insufficient and automatically stops the system.
   Non-ignition or Misfiring Detection	If the temperature of the exhaust gas detected by the flame sensor is low, the power heater ECU determines that a non-ignition or a misfiring condition exists and automatically stops the system.
   Open or Short Circuit Detection	If an open or short circuit exists in the sensors or actuators, the power heater ECU automatically stops the system.
   Air Fan Seizure Detection	If the air fan seizes, the power heater ECU automatically stops the system.

Air Conditioning Control Assembly (Models with Automatic Air Conditioning System)

1. A push button type air conditioning control assembly is used.

2. An air conditioning control assembly with Liquid Crystal Display (LCD) is used to ensure excellent visibility.

3. The temperature control can be set independently for the driver and front passenger sides.

   

   Text in Illustration

   *1

   LCD

   -

   -

Air Conditioning Unit Assembly

1. The air conditioning unit consists of the heater radiator unit sub-assembly, No. 1 cooler evaporator sub-assembly, No. 1 cooler thermistor, PTC heater (quick heater assembly) and damper servo sub-assemblies.

2. A semi-center location air conditioning unit, in which the heater radiator unit sub-assembly and No. 1 cooler evaporator sub-assembly are placed in the vehicle's longitudinal direction, is used.

   

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   *1	No. 1 Cooler Evaporator Sub-assembly	*2	Heater Radiator Unit Sub-assembly
   *a	Side View	*b	Top View
   	Front	-	-

3. A partial recirculation system is used. This system has an air inlet control door (sub) in the air inlet duct. Thus, it is able to cycle a small volume of recirculated air even in the FRESH mode, thus enhancing heating 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 (Sub)	*2	Air Inlet Control Door
   *3	Air Inlet Duct	-	-
   *a	RECIRC	*b	FRESH
   *c	To Blower Fan	-	-
   	Air Flow		Front

No. 1 Cooler Evaporator Sub-assembly

1. A Revolutionary super-Slim structure (RS) evaporator is used. By placing the tanks at the top and the bottom of the No. 1 cooler evaporator sub-assembly and by using a micropore tube construction, the following effects have been achieved:

   
   

   • Heat exchanging efficiency is ensured.

   • Temperature distribution is made uniform.

   • The No. 1 cooler evaporator sub-assembly is made thinner.

   

   Text in Illustration

   *1	Tank	*2	Micropore Tube
   *3	Cooling Fin	-	-

Servo Motor

1. In contrast to the previous type that detects the position by way of a potentiometer voltage, the 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 motor are detected by way of 2 phases, A and B, which output 4 types of patterns. The air conditioning amplifier assembly counts the number of pulse patterns in order to determine the stopped position.

   

Cooler Condenser Assembly

1. A Global Inner-fin Condenser (GIC) is provided. This condenser has tubes with high-density inner fins, and outer fins which allow the use of thinner cores, contributing to the efficiency of cooling performance. (Models with 1KR-FE Engine and 1NR-FE Engine)

2. The cooler condenser assembly consists of 2 cooling portions: a condensing portion and a super-cooling portion. These portions are integrated with a gas-liquid separator (modulator). This cooler condenser assembly uses a sub-cool cycle that offers excellent heat-exchange performance. (Models with 1KR-FE Engine and 1NR-FE Engine)

3. A sub-cool condenser is used. This is a multi-flow condenser consisting of 3 portions: a condensing portion, a super-cooling portion and a gas-liquid separator (modulator) all integrated together. This cooler condenser assembly uses a sub-cool cycle for its cooling cycle system to improve heat-exchanging efficiency. (Models with 1ND-TV Engine)

4. In the sub-cool cycle, after the refrigerant passes through the condensing portion of the cooler 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 No. 1 cooler evaporator sub-assembly in an almost completely liquefied state.

   

   Text in Illustration

   *1	Modulator	*2	Desiccant
   *3	Filter	*4	Super-cooling Portion
   *5	Condensing Portion	-	-
   *a	The illustrations shown are example only.	-	-
   	Gaseous Refrigerant		Liquid Refrigerant

Compressor with Pulley Assembly

1. The compressor with pulley assembly is a continuously variable capacity type with a capacity that varies in accordance with the cooling load of the air conditioning.

2. The compressor with pulley assembly consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder and solenoid control valve.

   

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   *1	Shoe	*2	Crank Chamber
   *3	Shaft	*4	Lug Plate
   *5	Piston	*6	Cylinder
   *7	Solenoid Control Valve	-	-

3. A variable suction side throttle is used.

   
   

   • Refrigerant inlet pressure is applied to the top of the variable suction side throttle and crank chamber pressure to the bottom of the variable suction side throttle.

   • The pressure difference moves the variable suction side throttle up and down, expanding and contracting the refrigerant inlet passage.

   • When the refrigerant flow is at a maximum, the refrigerant inlet pressure is greater than the crank chamber pressure. This causes the variable suction side throttle to move down, fully opening the refrigerant inlet passage and lowering the refrigerant inlet resistance.

   • When the amount of refrigerant flow is controlled, the crank chamber pressure is greater than the refrigerant inlet pressure, raising the variable inlet throttle to contract the flow passage.

   • These controls suppress noise by reducing pulsation from the refrigerant inlet.

   

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   *A	Maximum Volume of Refrigerant	*B	Controlled Volume of Refrigerant
   *1	Refrigerant Passage A	*2	Inlet Chamber
   *3	Variable Suction Side Throttle	*4	Crank Pressure Inlet Chamber
   *5	Compressor with Pulley Assembly	-	-
   *a	High Flow	*b	Low Flow
   	Crank Chamber Pressure		Refrigerant Flow

4. A Damper Limiter (DL) type air conditioning pulley is used. A cylinder-type damper is used for this compressor with pulley assembly and the torque fluctuations have been suppressed, thus making the inertia weight* unnecessary. As a result, the weight of the compressor with pulley assembly has been reduced.

   
   

   • *: Except for cold area specification models equipped with the 1KR-FE and 1NR-FE engines.

   

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   *A	5TSE10C Compressor	*B	Conventional Type Compressor
   *1	Damper	*2	Inertia Weight

Sub-cool Accelerator Type Tube (Models using HFO-1234yf refrigerant)

1. A sub-cool accelerator type tube is used to enhance air conditioning cooling performance. It functions as a heat exchanger by making use of the temperature difference between the gaseous refrigerant and liquid refrigerant.

2. The sub-cool accelerator type tube has a double-pipe construction. Helical grooves are embossed into the outer wall of the inner tube. Low-temperature and low-pressure gaseous refrigerant passes through the inner tube. High-temperature and high-pressure liquid refrigerant circulates between the inner tube and outer tube in the gap created by the grooves. Because of the temperature difference, heat exchange occurs.

3. The high-temperature and high-pressure liquid refrigerant circulate along the helical grooves causing the refrigerant to remain in contact with the outer wall of the inner tube for a longer period of time. This achieves an ample exchange of heat.

4. By lowering the temperature of the refrigerant that has passed through the cooler condenser assembly, more liquid refrigerant is supplied to the evaporator and the evaporator is also kept cooler. This enables an enhanced air conditioning cooling effect.

   

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 with fan motor sub-assembly.

   

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   *1	Blower with Fan Motor Sub-assembly	*2	Clean Air Filter
   *3	Air Filter Case	-	-

PTC Heater (Quick Heater Assembly)

1. The PTC heater (quick heater assembly) is located above the heater radiator unit sub-assembly in the air conditioning unit.

2. The PTC heater (quick heater assembly) consists of a Positive Temperature Coefficient (PTC) element, an aluminum fin and a 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 Element	*2	Aluminum Fin
   *3	Brass Plate	-	-

Combustion Type Power Heater

1. The combustion type power heater consists mainly of a heater exchanger, glow plug, blower motor, air fan, power heater ECU, engine coolant temperature sensor, an overheating prevention sensor, a flame sensor, an intake pipe, an exhaust pipe and a fuel pump.

2. This heater is installed between the engine and heater radiator unit sub-assembly. The engine coolant from the engine flows through the spiral passage around the heat exchanger and flows into the heater radiator unit sub-assembly. At this time, the glow plug ignites the air and fuel in the combustion chamber of the heat exchanger, and the resultant heat of combustion heats the engine coolant.

3. A power heater switch (heater switch assembly) is located in the No. 2 lower instrument panel finish panel.

   

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   *1	Power Heater ECU	*2	Blower Motor
   *3	Combustion Chamber	*4	Fuel Pump
   *5	Exhaust Pipe	*6	Heat Exchanger
   *7	Overheating Prevention Sensor	*8	Intake Pipe
   *9	Engine Coolant Temperature Sensor	*10	Power Heater Switch (Heater Switch Assembly)
   *11	Heater Radiator Unit Sub-assembly	*12	Engine
   	Exhaust Gas		Intake Air

   

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   *1	Fuel	*2	Flame Sensor
   *3	Glow Plug	*4	Air Fan
   *a	To Heater Radiator Unit Sub-assembly	*b	From Engine
   	Engine Coolant Flow	-	-

Mode Position and Door Operation

Control Damper	Operation Position		Damper Position	Operation
Air Inlet	FRESH		A	Brings in fresh air.
	RECIRCULATION		B	Recirculates internal air.
Air Mix	MAX COLD to MAX HOT		C to D (C' to D')*	Varies the mixture ratio of the fresh air and the recirculation air in order to regulate the temperature continuously from HOT to COLD.
Mode		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.

• *: Models with automatic air conditioning system

Air Outlets and Airflow Volume

Indication	Mode	A	B	C	D
		Center	Side	Foot	Defroster
	FACE			-	-
	BI-LEVEL				-
	FOOT	-
	FOOT/DEF	-
	DEF	-		-