Car Air Conditioning System and Components of Air Conditioning System

Explore Automotive going to give you detailed information about Car air conditioning system and the components of air conditioning system.

Introduction

Before we going to learn how car AC repair? we must learn about Air Conditioner, What is air conditioner? Air conditioning system is that, the science of controlling the temperature, humidity, motion and cleanliness of the air within an enclosure. 

In passenger or driver cabin of a vehicle, air conditioning system means that controlling the different terms and cozy environment within the passenger cabin during summer and winter, that is control the temperature (for cooling or heating), control humidity (decrease or increase), control of air circulation and ventilation (amount of air flow and fresh intake vs. partial or full re-circulation), and cleaning of the air from odor, pollutants, dust, pollen, etc. before entering the cabin.

While the A/C system provides comfort to the passengers during a vehicle, its operation during a vehicle has two fold impact on fuel consumption:

(1) Burning of extra fuel which is required to power the compressor for A/C operation, and

(2) carrying extra A/C component load within the vehicle all the time.

Additionally, the A/C running depends on the climatic condition of the concerned countryside and therefore the time of the year. 

The foremost important impact on the fuel economy is when the A/C is running. In this process extra fuel consumption takes place thanks to MAC operation as 2.5 to 7.5% (in USA/Europe) considering the climate, engine type (diesel or gasoline) and user profile.

Corresponding CO2 emission thanks to MAC operation is between 54.7 and 221.5 kg CO2 per annum per vehicle. Of course, the impact on the fuel consumption by the vehicle is more significant when the A/C is installed in a compact and sub-compact vehicles. And there is one another option comes out that is portable car air conditioner.

              

Basic Operation of Current Automotive A/C Systems

There are two major sorts of A/C systems are utilized in the vehicles: RD-TXV and AD-OT.

Working of Air Conditioner

As we know when we turn on A/C in car one question comes in our mind that is How does car A/C works? And if car A/C not working that time we search that ‘car A/C repair near me’, Right! And also so many questions arise in our mind regarding car A/C. So let’s see the actual working of car air conditioning system and different components used for automotive air conditioning system.

We now describe the essential operation of this technique starting with the compressor. At very first, the main function of compressor is to compress and pressurize the gaseous cool refrigerant from the evaporator outlet with using minimum compressor power driven by engine using belt drive, and deliver maximum amount of high-pressure and high-temperature gaseous refrigerant to the condenser unit.

These objectives are measured by isentropic and volumetric efficiencies. The compressor is powered by a drive belt connected from the engine.

The compressor has an electrically operated by the engagement clutch to either turn the A/C system on or off. Next is that the condenser; the condenser is found ahead of the radiator.

In automotive A/C systems, the condenser is usually a crossflow device that uses air through the fins and therefore the refrigerant through the tubes.

Through the utilization of cooled airflow provided by the engine condenser fan or ram air, the condenser cools the high-pressure hot refrigerant gas and converts it into the liquid with small amount of pressure drop.

The exiting liquid (subcooled in many cases) is shipped via a little tube (liquid line) to a receiver-drier (RD) (applies only to an expansion valve system). The RD may be a metal can with a desiccant bag inside. 

It's usually located near the condenser outlet pipe. Now-a-days, the RD bottle is an integral a part of the condenser, and condenser is mentioned as an integral receiver-drier condenser (IRDC). During this case, refrigerant passes through the RD bottle before leaving the condenser through the last pass. 

The target is to enhance the degree of sub-cooling of refrigerant at the condenser outlet. There's a negligible pressure/temperature change within the refrigerant through the RD bottle, except that the moisture is removed by the desiccant.

The moisture ingression and dirt particles within the refrigerant loop which is presents in the air conditioning system can internally corrodes the evaporator device, thermostatic expansion valve (TXV) and clog the orifice tube (OT) of the TXV (Thermostatic Expansion Valve) until remove those corroded particles or debris. Because of the high-pressure warm liquid exits the RD/condenser, it passes through an expansion device.

It are often either thermostatic expansion valve (TXV) which modulates refrigerant flow during a TXV/RD system, or a hard and fast diameter orifice tube (OT) in an OT/AD (accumulator-drier) system.

Effectively, the TXV features a variable diameter orifice tube and OT features a fixed diameter orifice tube. Thus TXV allows more refrigerant flow at idle compared there to for the OT thus providing higher cooling.

The TXV which maintains the desired refrigerant superheat at the exit of the evaporator. The OT (Orifice Tube) which cannot be control the refrigerant exit condition from the OT or evaporator. The pressurized liquid passes through the expansion device, with considerable reduction within the pressure and corresponding temperature.

And that cold liquid/vapor refrigerant mixture from the expansion device is fed to an evaporator device in an HVAC module which is placed under the dashboard. It cools fresh or recirculated warm air, which flows into the car interior with the assistance of a blower. because the air is cooled within the evaporator on one fluid side, the liquid/ vapor mixture of the refrigerant is heated on the opposite fluid side and evaporates. 

The evaporated refrigerant gas then return via the massive tube (suction hose) to the compressor "suction" port to restart this whole process again.

Types of Air Conditioning System
There are two main types of Air conditioning system which is as follows:

1. NASH Integrated System

First American automobile to possess a front-end, fully integrated heating, ventilating, and air-conditioning system. 

The Nash-Kelvinator Corporation used its experience in refrigeration to introduce the car industry's first compact and affordable, single-unit heating and air con system optional for its Nash models.

This was the primary mass market system with controls on the dash and an electrical clutch. This system was also compact and simply serviceable with all of its components installed under the hood or within the cowl area.

Combining heating, cooling, and ventilating, the new air con. system for the Nash cars was called the "All-Weather Eye". This followed the marketing name of "Weather Eye" for Nash's fresh-air automotive heating and ventilation that was first utilized in 1938.

With one thermostatic control, the Nash passenger compartment air cooling option was described as "a good and remarkably inexpensive" system. 

Entirely incorporated within the engine bay, the combined heating and cooling system had cold air for passengers enter through dash-mounted vents and rear A/C vents present on the middle or side pillars of car. Nash's exclusive "remarkable advance" wasn't only the "sophisticated" unified system, but also its $345 price that beat all other systems.

2. Automatic Climate control A/C system

Most competing systems used a separate heating system and an engine-mounted compressor, driven off of the crankshaft of the engine via a belt drive, with an evaporator within the car's trunk which is able to deliver cold air through the rear parcel shelf having vents and overhead vents.

In 1954, General Motors made a front mounted air conditioning system optional on Pontiacs with a straight-eight engine that added separate controls for the same and air distribution via vents. 

The alternative layout pioneered by Nash is that, "became established practice and continues to form the thought of the fashionable and more sophisticated automatic climate control systems."

Components of Air Conditioning System

Major components of an automotive A/C system are as follows:

Compressor, condenser, an expansion device and an evaporator which are described as below. Additionally, tubes and hoses are required to attach these components, and controls and switches for correct operation of the A/C system and necessary shutdown conditions.

1. Compressor

The air con. compressor is typically driven by the engine via a belt or ribbed V-belt. The compressor compresses and transports the refrigerant within the system. There are different designs available. There are various makes and types of compressors utilized in automotive air con systems operating on R134a.

The internal design might be Piston, Scroll, Wobble plate, Variable stroke or Vane. Regardless, all operate because the pump within the A/C system to stay the R134a and grease circulating, and to extend the refrigerant pressure and thus temperature.

2. Condensers

The capacitor is required so as to chill the refrigerant that's heated by the compression within the compressor. The hot refrigerant gas flows into the condenser and transfers heat to the environment via the pipe and fins. As it cools down, the state of the refrigerant flowing through pipe of condenser changes again from gaseous to the liquid state.

The Condenser function is to act as a device and permit heat to be due the recent refrigerant to the cooler outside air. Considering R134a entering the condenser is going to be a high-pressure heat vapor.

In some other words, as the R134a vapor travels through the tubes of the condenser heat is given off to the cooler ambient air; at that time the refrigerant vapor condenses and changes to the liquid state. At now an outsized amount of warmth is given off by the R134a. The refrigerant will now be a hot, high liquid.

3. Filter Dryer

The filter elements of the air con. system are either mentioned as filter dryers or accumulators, counting on the sort of system. The task of the filter dryer is to get rid of impurities from the refrigerant and to dehumidify it.

4. Expansion Valve

The expansion valve represents the purpose of separation between the high and low sections within the refrigerant circuit. It is installed in upstream of the evaporator. 

To achieve optimum cooling capacity within the evaporator, the refrigerant flow is controlled by the expansion valve counting on the temperature. As a result, complete evaporation of the liquid refrigerant came from condenser via filter dryer is ensured and refrigerant arrives at the compressor gaseous state only. Expansion valves may differ in their design.

5. Evaporator

The evaporator is employed to exchange heat between the ambient air and therefore the refrigerant within the air con system.

6. Pressure Switch

Pressure switches are responsible for protecting the air conditioning system against damage caused by too high or too low pressures. There are low pressure switches, high pressure switches and trinary switches. 

The trinary switch comprises the high switch and therefore the low switch and a further switch contact for the condenser fan.

7. Ventilation Fan

The ventilation fan is used to ventilate the passenger car. It ensures clear visibility and a pleasing interior climate. Major pre-requisites for safe and comfortable driving.

8. Condenser Fan

The condenser fan helps to ensure the optimal liquefaction of the refrigerant no matter what operating state the vehicle is in. It is mounted upstream or downstream of the condenser and/or engine cooling system as a further or combination fan.