System Description

GENERAL

The air conditioning system has the following controls:

Control	Outline
Variable Capacity Compressor Control	Controls the compressor to turn ON or OFF and the discharge capacity based on the signals from various sensors.
Self-diagnosis	Checks the sensors in accordance with operation of air conditioner switches, then clock displays a DTC (Diagnosis Trouble Code) to indicate if there is a malfunction or not (sensor check function).

MODE POSITION AND DAMPER OPERATION

Mode Position and Damper Operation

Fig 1: Identifying Mode Position And Damper Operation

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002© TOYOTA, LICENSE AGREEMENT TMS1002© TOYOTA, LICENSE AGREEMENT TMS1002© TOYOTA, LICENSE AGREEMENT TMS1002© TOYOTA, LICENSE AGREEMENT TMS1002© TOYOTA, LICENSE AGREEMENT TMS1002

FUNCTIONS OF MAIN DAMPERS

Control Damper	Operation Position	Damper Position	Operation
Air Inlet Control Damper	FRESH	A	Brings in fresh air.
Air Inlet Control Damper	RECIRC	B	Recirculates internal air.
Air Mix Control Damper	MAX COLD to MAX HOT Temperature Setting 16°C (61°F) to 30°C (86°F)	C - D - E	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 Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	H, K	Defrosts the windshield through the front defroster and side register.
	FOOT / DEF Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	H, J	Defrosts the windshield through the front defroster and side register, while air is also blown out from the front footwell register duct and rear foot well register duct*2.
	FOOT Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	H, I	Air blows out of the footwell register duct, rear footwell register duct*2, and side register. In addition, air blows out slightly from the front defroster.
	BI-LEVEL Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	F, I	Air blows out of the center register, side register, front footwell register duct and rear footwell register duct*2.
	FACE Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	F, K	Air blows out of the center register and side register.

*2: Models with Cold Area Specification

AIR OUTLETS AND AIRFLOW VOLUME

Air Outlets and Airflow Volume

Fig 2: Locating Air Outlets

INDICATION (MODE)	CTR	SIDE	FOOTWELL	DEFROSTER
INDICATION (MODE)	A	B	C	D
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002 FACE	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002 BI-LEVEL	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002 FOOT	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002 FOOT/DEF	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002 DEF	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002	Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The size of the circle ◦ indicates the proportion of airflow volume.

A/C COMPRESSOR
1. General
  1. The A/C compressor is a continuously variable capacity type in which its capacity varies with the cooling load of the air conditioning system.
  2. The compressor consists of the shaft, lug plate, piston, shoe, crank chamber, cylinder, and solenoid control valve.
  3. The solenoid control valve is provided to enable the suction pressure to be controlled as desired.
  4. The plastic DL (Damper Limiter) type A/C pulley is used.
  5. The rotary valve uses suction to pull refrigerant gas into the cylinder.
    
    Fig 3: Identifying A/C Compressor Components
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Operation
  1. The crank chamber is connected to the suction passage. A solenoid control valve is provided between the suction passage (low pressure) and the discharge passage (high pressure).
  2. The solenoid control valve duty cycle is controlled in accordance with the signals from the air conditioning amplifier.
    
    Fig 4: A/C Compressor Operation Diagram
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. When the solenoid control valve closes (solenoid coil is energized), a difference in pressure is created and the crank chamber pressure decreases. Then, the pressure applied to the right side of the piston becomes greater than that applied to the left side. This compresses the spring and tilts the lug plate. As a result, there is a large piston stroke and discharge capacity increases.
    
    Fig 5: A/C Compressor Operation Diagram
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. When the solenoid control valve opens (solenoid coil is not energized), the pressure is equalized. The pressure applied to the left side of the piston becomes equal to the right side. This is performed when the spring elongates and eliminates the tilt of the lug plate. As a result, there is a small piston stroke and the discharge capacity decreases.
    
    Fig 6: A/C Compressor Operation Diagram
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
PTC HEATER (w/ PTC Heater Assembly)
1. General
  1. The PTC heater is located above the heater core 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.
    
    Fig 7: Identifying PTC Heater, PTC Element, Aluminum Fin And Brass Plate
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. PTC Heater Operating Conditions
  1. The PTC heater is turned on and off by the air conditioning amplifier in accordance with the water temperature, ambient temperature, engine speed, air mix setting and electrical load (generator power ratio).
    For example, the number of the operating PTC heaters varies by the water temperature as in the graph below.
    
    Fig 8: PTC Heater - Heating Pattern
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
AMBIENT TEMPERATURE SENSOR
The ambient temperature sensor detects the outside temperature based on changes in the resistance of its built-in thermistor and sends a signal to the A/C amplifier.
EVAPORATOR TEMPERATURE SENSOR
The evaporator temperature sensor detects the temperature of the cool air immediately past the evaporator in the form of resistance changes, and outputs it to the A/C amplifier.
A/C PRESSURE SENSOR
The A/C pressure sensor detects the refrigerant pressure and outputs it to the A/C amplifier in the form of voltage changes.
A/C FLOW SENSOR (for 2ZR-FE)
The A/C flow sensor, which is mounted on the A/C compressor, is used to detect the amount of refrigerant flow. The A/C flow sensor converts the amount of refrigerant flow that is detected to a voltage value to send it to the A/C amplifier. The voltage value sent from the A/C flow sensor changes depending on the amount of refrigerant flow. As the amount of refrigerant flow becomes larger, the voltage becomes lower. As the amount of refrigerant flow becomes smaller, the voltage becomes higher. The A/C amplifier supplies 5 V to the A/C flow sensor and monitors change in the voltage value sent from the A/C flow sensor. The A/C amplifier then sends a signal to the ECM via CAN communication to allow the ECM to control the engine speed while the air conditioning is on.