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 cooler compressor assembly stops operating.

   

Quick Heater Control

1. The on/off function of the 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 heating value of the operating quick heater assembly varies depending on the engine coolant temperature, as shown in the graph below:

   

   *a	Heating Value
   *b	Engine Coolant Temperature

Combustion Type Power Heater Control

1. Igniting

   When the engine is operating, turning the power heater switch 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. Extinguishing

   When the ignition switch is turned off or the power heater switch 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. During Operation

   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. Protective Function

   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 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 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 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 ECU automatically stops the system.
   Air Fan Seizure Detection	If the air fan seizes, the ECU automatically stops the system.

Pollen Removal Mode Control

1. When the pollen removal mode switch is pressed, the pollen removal mode control is activated. Then, the air outlet is switched to the FACE mode and recirculated pollen-free air flows in the area around the upper part of the bodies of the driver and front passenger.

2. When the pollen removal mode switch signal is input to the air conditioning amplifier assembly, the air conditioning amplifier assembly controls the damper servo sub-assembly, blower with fan motor sub-assembly and cooler compressor assembly as shown in the timing chart below:

   

3. This control usually operates for approximately 3 minutes. However, when the ambient temperature is low (5°C [41°F] maximum), it will operate for approximately 1 minute.

4. After this control stops operating, the air conditioning amplifier assembly automatically returns to the mode it was in just before the pollen removal mode switch was pressed.

Air Conditioning Unit

1. The air conditioning unit consists of the heater radiator unit sub-assembly, No. 1 cooler evaporator sub-assembly, No. 1 cooler thermistor, blower with fan motor sub-assembly, clean air filter, quick heater assembly*1 and damper servo sub-assembly*2.

   
   

   • *1: Models with quick heater assembly

   • *2: Models with automatic air conditioning

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.

   

   Text in Illustration

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

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).

   

   Text in Illustration

   *1	Air Inlet Control Door (Sub)	*2	Air Inlet Control Door
   *3	Air Inlet Duct	-	-
   *a	Front	*b	RECIRC
   *c	FRESH	*d	To Blower Fan

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 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.

2. 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	-	-
   	Gaseous Refrigerant		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 will 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 to recharge the system with refrigerant, refer to the Repair Manual.

   

   *1	Properly Recharged Amount
   *2	High Pressure
   *3	Point at which Bubbles Disappear
   *4	Amount of Refrigerant

Cooler Compressor Assembly

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

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

   

   Text in Illustration

   *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.

   
   

   1. 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.

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

   3. 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.

   4. 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.

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

   

   Text in Illustration

   *1	Refrigerant Passage A	*2	Inlet Chamber
   *3	Variable Suction Side Throttle	*4	Crank Pressure Inlet Chamber
   *5	Cooler Compressor Assembly	-	-
   *a	With Maximum Volume of Refrigerant	*b	With Controlled Volume of Refrigerant
   *c	High Flow	*d	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 the this cooler compressor assembly and the torque fluctuations have been suppressed, thus making the inertia weight unnecessary. As a result, the weight of the cooler compressor assembly has been reduced.

   

   Text in Illustration

   *1	Damper	*2	Inertia Weight
   *a	5TSE10C Cooler Compressor Assembly	*b	Conventional Type Cooler Compressor Assembly

Clean Air Filter

1. A high efficiency 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.

   

   Text in Illustration

   *1

   Clean Air Filter

   -

   -

   Tech Tips

   See the table below regarding the replacement intervals for the high efficiency type clean air filter. Replace the clean air filter after the ignition switch has been turned off.

   Condition	Destination
   	Europe	Others
   Normal Condition	30000 km (18000 miles)	20000 km (12000 miles)
   Dusty Condition	15000 km (9000 miles)	15000 km (9000 miles)

Quick Heater Assembly

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

2. The 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.

   

   Text in Illustration

   *1	PTC Element	*2	Aluminum Fin
   *3	Brass Plate	-	-

Combustion Type Power Heater

1. The combustion type power heater assembly consists mainly of a heater exchanger, a glow plug, a blower motor, an air fan, an ECU, an 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.

   

   Text in Illustration

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

   

   Text in Illustration

   *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 Damper Operation

Control Damper	Operation Position		Damper Position	Operation
Air Inlet Control Damper	FRESH		A	Brings in fresh air.
	RECIRC		B	Recirculates internal air.
Air Mix Control Damper	MAX COLD to MAX HOT		C - D	Varies the mixture ratio of the cold air and the hot air in order to regulate the temperature continuously from HOT to COLD.
Mode Control Damper		FACE	E, G	Air blows out of the center register and side register.
		BI-LEVEL	F, G	Air blows out of the center register, side register, front footwell register duct and rear footwell register duct*.
		FOOT	F, I	Air blows out of the front footwell register duct and rear footwell register duct*. In addition, air blows out slightly from the side register and the defroster.
		FOOT/DEF	F, H	Air blows out of the defroster, side register, front footwell register duct and rear footwell register duct*.
		DEF	E, J	Air blows out of the defroster and side register.

• *: Models with rear footwell register duct

Air Outlets and Airflow Volume

Indication	Mode	A	B	C	D
		Center	Side	Front Footwell/Rear Footwell*	Defroster
	FACE			-	-
	BI-LEVEL				-
	FOOT	-
	FOOT/DEF	-
	DEF	-		-

• *: Models with rear footwell register duct