AIR CONDITIONING SYSTEM DETAILS

PTC Heater Control

1. The PTC heater is controlled by the air conditioning amplifier in accordance with the engine coolant temperature, engine speed, air mix setting, ambient temperature and electrical load (generator power ratio). For example, the number of the operating PTC heaters varies with engine coolant temperature as in the graph below.

   

Heater Control Panel (for Automatic Control Type)

1. The rotary switch and push switch type heater control panel is used.

2. This heater control panel use an LCD (Liquid Crystal Display) to display the set temperature, air outlet mode and blower speed to ensure excellent visibility.

   

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   *a

   Automatic Air Conditioning Model

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Air Conditioning Unit Assembly

1. The center location air conditioning unit assembly, in which the No. 1 cooler evaporator sub-assembly and heater radiator unit sub-assembly are arranged longitudinally, is used.

2. The air conditioning unit assembly has been made more compact by incorporating the conventional blower fan unit into the center unit. The air conditioning unit assembly is located in the center area of the instrument panel. This provides sufficient foot space for the front passenger.

   

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   *1

   No. 1 Cooler Evaporator Sub-assembly

   *2

   Heater Radiator Unit Sub-assembly

No. 1 Cooler Evaporator Sub-assembly

1. The RS (Revolutionary super-slim Structure) type No. 1 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 evaporator body has been coated with a type of resin is capable of preventing the growth of various bacteria which can produce a bad odor which can stick to the evaporator surfaces.

4. The substrate for this coating material includes a chromate-free layer for environmental protection.

   

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

Blower with Fan Motor Sub-assembly

1. The blower with fan motor sub-assembly has a built-in blower controller, and is controlled using duty control performed by the air conditioning amplifier.

2. Compact and lightweight fan blades are used for the blower with fan motor sub-assembly. Smooth airflow around the fan has further improved and the power consumption and noise generation have been reduced by rotating the motor at high speed.

   

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   *1	Fan Blade	*2	Blower Controller (for Models with automatic air conditioning)
   *3	Blower Motor	-	-

Bus Connector (Models with Automatic Air Conditioning)

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

   

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   *1	Bus Connector	-	-
   *a	To Mode Control Servo Motor	*b	To Air Inlet Control Servo Motor
   *c	To Air Mix Control Servo Motor	*d	To Evaporator Temp. Sensor
   *e	To Air Conditioning Amplifier Assembly	-	-

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 (Models with Automatic Air Conditioning)

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 conditioning unit assembly.

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.

   

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   *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.

   

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   *1	Air Filter Case	*2	Clean Air Filter
   *a	Large Foreign Object Layer	*b	Electret Layer

   Tech Tips

   The filter should be changed at 30000 km (18000 miles) under normal conditions [cleaning interval: 15000 km (9000 miles)]. Under dusty conditions, the filter should be changed at 15000km (9000 miles) [cleaning interval: 7500 km (4500 miles)]. However, observation of these guidelines should depend on the usage conditions (or environment).

Cooler Condenser Assembly

1. A MF (Multi-Flow) type cooler condenser assembly is used. The cooler condenser assembly consists of two cooling portions: a condensing portion and a super-cooling portion, and gas-liquid separator (modulator) are integrated together. This cooler 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 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.

   

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   *1	Modulator	*2	Desiccant
   *3	Filter	-	-
   *s	Condensing Portion	*b	Super-cooling Portion
   *c	Gaseous Refrigerant	*d	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.

   

Cooler Compressor Assembly

1. Cooler Compressor Assembly

   
   

   • The cooler compressor assembly is continuously variable capacity type in which its capacity can be varied in accordance with the cooling load of the air conditioning.

   • The cooler compressor assembly consists of the A/C pulley with magnet clutch, shaft, lug plate, swash plate, piston, shoe, crank chamber, cylinder and solenoid control valve.

   • A solenoid control valve that adjusts the suction pressure so that the compressor capacity can be controlled as desired is provided.

   • The cooler compressor assembly has a flow volume sensing mechanism which uses a refrigerant flow volume sensor, oil separator mechanism, variable suction side throttle and solenoid control valve with CS valve. As a result, the cooling efficiency has been improved while simultaneously increasing the power saving ability.

   

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   *1	A/C Pulley with Magnet Clutch	*2	Solenoid Control Valve
   *3	Crank Chamber	*4	Shoe
   *5	Swash Plate	*6	Piston
   *7	Cylinder	*8	Lug Plate
   *9	Shaft	-	-
   *a	Flow Volume Sensing Mechanism	*b	Oil Separator Mechanism
   *c	Variable Suction Side Throttle	-	-

2. Solenoid control valve with CS valve

   
   

   • If the vehicle has been left for a long time, the temperature of the cooler compressor assembly, which has the largest heat capacity among the air conditioning system devices (such as the cooler condenser assembly and No. 1 cooler evaporator sub-assembly), will decrease due to the differences of the heat capacities. At this time, refrigerant may accumulate inside the cooler compressor assembly. If this occurs, the cooler compressor assembly cannot increase its capacity until the liquid refrigerant is fully discharged. Since a conventional cooler compressor assembly has a single passage for discharging refrigerant, it takes several tens of seconds until the capacity is increased. In addition to the conventional discharge passage, the cooler compressor assembly used on iQ has another discharge passage that will open only when refrigerant accumulates inside the solenoid control valve. As a result, the time required for discharging the refrigerant has been significantly shortened and the immediate cooling effect has been further improved.

   • The CS valve is built into the shaft inside the solenoid control valve instead of being placed outside the solenoid control valve. This allows the refrigerant to discharge more easily and minimizes the size increase of the cooler compressor assembly.

   

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   *1	Solenoid Control Valve with CS Valve	*2	Conventional Solenoid Control Valve
   	Continuous Hole	-	-

3. Flow volume sensing mechanism

   
   

   • Conventionally, the workload (compressor torque) of the cooler compressor assembly was estimated based on the current and high pressure of the solenoid control valve. The flow volume sensing mechanism used on the new iQ can estimate the compressor torque more accurately using a refrigerant flow volume sensor. Thus, load condition data of the cooler compressor assembly is used for engine controls as feedback with high accuracy, and the compressor is controlled efficiently, saving power while operating the air conditioning system.

   • The cooler compressor assembly uses the refrigerant flow volume sensor, which detects the flow volume of discharged refrigerant based on the changes in the magnetic flux of a spool. The refrigerant passage becomes narrower at one point so that the differential pressure before and after that point changes depending on the flow volume of the refrigerant. The differential pressure is then introduced into the upper and lower sides of the spool to change the spool position. The magnetic sensor portion detects the position of the magnet built into the spool and converts it into the flow volume of the refrigerant. Then the compressor torque is calculated based on the flow volume of the refrigerant.

   

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   *1	Refrigerant Flow Volume Sensor	*2	Spool
   *3	Magnet	-	-
   *a	Magnetic Sensor Portion	*b	Narrow Refrigerant Passage
   	Flow of Refrigerant	-	-

4. Oil separator mechanism

   
   

   • Conventionally, the cooler compressor assembly mixes oil into the refrigerant that is sucked into the compressor to ensure smooth sliding of each portion. Since the refrigerant containing oil is discharged from the cooler compressor assembly, the oil that does not contribute to the refrigerant effect circulates in addition to the refrigerant itself in the air conditioning system operation cycle. As a result, the cooling efficiency was compromised. By providing an oil separator in the cooler compressor assembly, most of the oil can be stored inside the cooler compressor assembly and most of the refrigerant can be circulated in the air conditioning system operation cycle. As a result, the cooling efficiency has been significantly improved and the air conditioning system also consumes less power as a result.

   • The oil separator mechanism uses a centrifugation method that has a high separation efficiency and separates the oil from the refrigerant in the separation chamber. The oil circulates inside the cooler compressor assembly along a route in the order of the separation chamber, oil storage chamber, suction chamber, cylinder and discharge chamber, then returns to the separation chamber. As a result, the mechanism prevents the oil from being discharged from the cooler compressor assembly.

   Tech Tips

   Centrifugation is a method to separate liquids with specific gravity difference using a force applied to the axis of rotation in the vertical direction (centrifugal force) by rotating them at high speed.

   

5. Variable Suction Side Throttle

   
   

   • The cooler compressor assembly uses the variable suction side throttle, which adjusts the refrigerant suction passage according to heat load or vehicle running conditions. When the capacity of the cooler compressor assembly is controlled, the throttle is closed according to the flow volume of refrigerant to reduce pulsation. At the maximum capacity of the cooler compressor assembly, the throttle is fully opened to prevent an increase in suction resistance of the cooler compressor assembly due to the throttle being closed.

   

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

• *: for S-class cold area specification models equipped with rear seat

Air Outlets and Airflow Volume