Heating and Air Conditioning: Description and Operation

AIR CONDITIONING: AIR CONDITIONING SYSTEM: SYSTEM DIAGRAM

SYSTEM DIAGRAM









Input signal to A/C amplifier:





Output signal to A/C amplifier:





AIR CONDITIONING: AIR CONDITIONING SYSTEM: SYSTEM DESCRIPTION

SYSTEM DESCRIPTION

1. GENERAL
(a) The air conditioning system has the following features:
- An ES27 type electric inverter compressor is used on the vehicle. This compressor is driven by the alternating current that is supplied by the A/C inverter, which is integrated with the compressor. 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.
- A compact, lightweight, and highly efficient electrical water pump is used in order to ensure the proper heater performance while the engine is stopped.
- The left/right independent temperature control and neural network control allows the air conditioner to be set to suit the preferences of the persons in the driver seat and passenger seat. An automatic air conditioner is standard in all models.
- A compact, lightweight, and highly efficient straight flow (full-path flow) aluminum heater core is used.
- A revolutionary slim structure evaporator is used.
- The room temperature sensor has a humidity sensor function in order to optimize the amount of dehumidification during the operation of the air conditioning system.
- The clean air filter has a pollen reduction function.
- The A/C amplifier is equipped with a self-diagnosis function. If there is a malfunction in the system, it stores the DTCs (Diagnostic Trouble Codes) in its memory.
- In compliance with the temperature set with the temperature control switch, the A/C amplifier calculates the outlet temperature based on the input signals from various sensors. In addition, corrections in accordance with the signals from the room humidity sensor and the water temperature sensor are added to control the outlet air temperature.
- Controls the blower motor in accordance with the airflow volume that has been calculated by A/C amplifier based on the input signals from various sensors.
- Automatically changes the outlets in accordance with the outlet mode ratio that has been calculated by the A/C amplifier based on the input signals from various sensors.

2. MODEL POSITION AND DAMPER OPERATION









HINT: *1: In the multi mode, air blows out of all the air outlets except the front and side defroster.
*2: In the multi mode, air blows out of all the air outlets.

3. AIR OUTLETS AND AIRFLOW VOLUME













HINT: The size of the circle indicates the proportion of airflow volume. There are 4 sizes.

4. COMPRESSOR

General

- Along with the installation of the hybrid unit on the vehicle, an ES27 electric inverter compressor that is driven by a built-in DC 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.
- The A/C inverter has been integrated with the compressor.
- The electric motor is actuated by the alternating current power (288 V) supplied by the A/C inverter. As a result, the air conditioner control system on the vehicle is actuated without depending on the operation of the engine, thus realizing a comfortable air conditioning system and low fuel consumption.
- Due to the use of an electric inverter compressor, the compressor speed can be controlled at the required speed calculated by the A/C amplifier. Thus, the cooling and dehumidification performance and power consumption have been optimized.
- Low-moisture permeation hoses are used for the suction and discharge hoses at the compressor in order to minimize the entry of moisture into the refrigeration cycle.
- The compressor uses high-voltage alternating current. If a short or open circuit occurs in the compressor wiring harness, the hybrid vehicle control ECU will cut off the A/C inverter circuit in order to stop the power supply to the compressor.

Service Tip:
In order to ensure proper insulation of the internal high-voltage portion of the compressor and the compressor housing, use ND-OIL 11 compressor oil (which has a high level of insulation performance) in the vehicle. Never use a compressor oil other than ND-OIL 11.

Construction

- The electric inverter compressor consists of a spirally wound fixed scroll and variable scroll that form a pair, a brushless motor, an oil separator, a motor shaft and A/C inverter.
- The fixed scroll is integrated with the housing. Because the rotation of the shaft causes the variable scroll to remove while maintaining the same posture, the volume of the space that is partitioned by both scrolls varies to perform the suction, compression, and the discharge of the refrigerant gas.
- Locating the suction port directly above the scrolls enables direct suction, thus realizing suction efficiency.
- Containing a built-in oil separator, this compressor is able to separate the compressor oil that is intermixed with the refrigerant and circulates in the refrigeration cycle, thus realizing an efficient in the oil circulation rate.
- This inverter converts the HV battery's nominal voltage of DC 288 V into AC 288 V and supplies power to operate the compressor.

System Diagram:





Electric Inverter Compressor Control

- The A/C amplifier calculates the target compressor speed based on the target evaporator temperature (calculated from the room temperature sensor, humidity sensor, ambient temperature sensor, and solar sensor (automatic light control sensor)) and the actual evaporator temperature detected by the evaporator temperature sensor. Then, the A/C amplifier transmits the target speed to the hybrid vehicle control ECU controls the A/C inverter based on the target speed data in order to control the compressor to a speed that suits the operating condition of the air conditioning system.
- The A/C amplifier calculates the target evaporator temperature, which includes corrections based on the vehicle interior humidity (which is obtained from the humidity sensor) and the windshield glass inner surface humidity (which is calculated from the humidity sensor, solar sensor (automatic light control sensor), room temperature sensor, mode damper position, and wiper operation condition). Accordingly, the A/C amplifier controls the compressor speed to an extent that does not inhibit the proper cooling performance or defogging performance. As a result, comfort and low fuel consumption can be realized.