1.1 INTRODUCTION
Over the years, all the tropical countries have been faced with the problem of air around them. The relative humidity of air in most of the tropics is very low; Hence the comfort is not there with the populace especially in the places of work. This consequently reduces the work rate of workers thereby affecting the GROSS NATIONAL PRODUCT of a country.
To this effect, the engineers and scientists are looking into the methods of bringing comfort to the people while at home and at work. They produced an appliance to help produce a cooler temperature for individuals known as AIR CONDITIONER. This appliance has been in operation for a very long time but most users prefer dumping their old ones for new Air conditioner due to lack of knowledge on how to maintain, repair or even rehabilitate minor faults in an air conditioner.

1.2 LITERATURE REVIEW
The origin of an air conditioner is necessary to trace. Its original conception, and the people that were involved in its production at its initial state.
An air conditioner was gradually developed and produced for cooling, cleaning heating and facilitating ventilating processes such as:
The end of the 15th century, Leonardo da rinci had built the first ventilating fan.
In the year 1959, Boyle and also in the year 1800, Dalton discovered both discovered laws for ideal gases.
In 1815 Robertson Buchanan published the first book on heating and ventilation.
In the middle of the 19th century fans, boilers and radiators had been invented.
In 1834, Alexander Twinning started commercial production of water ice, using the compression pump and sulphuric either as refrigerant.
Second half of 19th century, brought about the further development of ice making and air conditioning processes.
In the 20th century, Willis H. Carrier who is known as the “Father of Air Conditioning” designed and installed the first year round air conditioning system. It was performing the four major functions of heating, cooling, humidifying and dehumidifying of the air or rather using the air washer.
Willis H. Carrier (1976 – 1950) developed the applications of a forced draft fans, pipe coil heaters, centrifugal compressors, invented a psychometric chart and generally laid down the theory of air conditioning on a complete thermodynamic basis. On the most famous paper “Regional psychometric formulae” published in the year 1911, Willis Carrier related the dry bulb, we bulb; dew point temperatures of air with its sensible, latent and total heat and presented a theory adiabatic chart.
Air conditioning was increasingly been in use after Willis carrier’s invention; in cotton, rayon, silk, paper, tobacco, cady pharmaceutical and printing industries all around the world.
The first comfort for the people the air-conditioning was first installed in cinema building in 1920 in Chicago, employing dry ice machine and in 1922 in Los – Angeles using ammonia compressors.
This brought about an increase in demand and expansion in air conditioning equipments sales to cinema, office building, hostels, hospitals, airport terminal, departmental stores, banks, shops, and individual homes etc in the market, the buyers were assumed of better packages than the earlier ones.

1.3 WHAT IS AN AIR CONDITIONER
The provision of it can be defined as the process of treating air in order to clean or purify it, to control its temperature and humidity by heating or cooling and by humidifying and dehumidifying and to supply sufficient outdoor air for ventilation. The word air conditioning is employed to any process or system which fulfil all these requirements.

1.4 WHY WE USE AIR CONDITIONER
1. According to science, oxygen is needed for human life and for any living thing to stay alive, is one of the vital use of an air conditioner.
2. Air acts as a dilatants; ie the amount of air required depends on the permissible contaminant level for the room. The contaminant may be C02 human skin or omission from any other processes.
3. The air condition promotes air movement in t he space; this brings one of the environment comfort factors.
4. An air conditioner controls air borne contamination i.e industrial ventilation.

1.5 SIGNIFICANCE OF STUDY
The purpose of studying about Air – conditioner is to show how necessary it is needed in a house. In other words, when one owns this appliance and its not functioning properly due to a faulty in the system, this study is very important and a guide to the relevant steps of maintaining and knowing what one should do in order to discover a fault in the air conditioner and having a solution.

1.6 LIMITATION OF STUDY
We are expected to explore all avenues and ways of finding the simple and adequate procedures in repairing the Air conditioner given to us, our study without any exception or delineated areas are left out.
Proper maintenance of all types of air conditioner is the basis of our study.

1.7 BASIC COMPONENTS OF AN AIR CONDITIONER
The air conditioning system has four basic component parts. These are as follows:
1. Compressor
2. Condenser
3. Metering device
4. Evaporator
Furthermore, there are other components as follows:
1. Fan motor
2. Fan blade
3. Over load
4. Relay
5. Drier strainer
6. Thermostat
7. Flexible cable
8. Air conditioning junction box
9. Bulb
10. Fiber (lagging) material
11. Switch
12. The working fluid (refrigerant)
13. Back cover (Hide)
14. Capacitor
15. Filter
16. Grile
17. Fan Blower
18. Capillary

1.8 FUNCTIONS OF THE COMPONENTS
COMPRESSOR: The compressor can be explained as the heart of mechanical air conditioning system.
The compressor pumps the refrigerant gas throughout the entire system. It draws cool refrigerant gas through the suction line from the gas there by raising the pressure and temperature and then pumps it into the discharge line.
There are various types of compressor namely:
1. Rotary compressor
2. Reciprocating compressor
3. Centrifugal compressor
4. Screw compressor.
THE CONDENSER: The condenser is a component in the air conditioner, which transfers heat from air conditioning system to a medium where they can be absorbed and moves it to the final disposal point.
The condenser is the channel through which unwanted heat is liberated out of the air conditioning system. It is the condenser that superheated high pressured refrigerant vapour is cooled to its boiling (conferring) point by rejecting sensible heat. The additional rejection of latent heat causes the vapour to condense to the liquid state.
TYPES OF CONDENSER
1. Water cooled shell and cool condenser
2. Water cooled shell and tube condenser
3. Air cooled condenser
4. Evaporative condenser.
THE EVAPORATOR
The evaporator is a device in the low pressure side of an air conditioning system through which an unwanted heat flows. The evaporator absorbs the heat into system in order that it may be moved or transferred to the condenser. The evaporator is also known as a “cooling” blower cool, “Chilling unit “.
Its ultimate function is to absorb heat from the surrounding air or liquid and by means of refrigerant the heat is carried along out of the air-conditioned areas.
TYPES OF EVAPORATOR
1. Shell and tube direct expansion evaporator
2. Shell and tube flooded evaporator
3. Submerged coil evaporator
4. Boud lot/coolers.
OTHER COMPONENTS AND THEIR FUNCTIONS
DRIER/STRAINER: This serves as the filter for the filtration of the refrigerant gas, also small amount of heat reduction takes place in it.
OVER LOAD AND RELAY: These are sensitive materials inside the air conditioner, they serve the purpose of protecting the compressor by tripping off any unwanted current coming into the compressor thereby preventing damage to compressors.
THERMOSTAT: This can be explained as when the air conditioner attains its maximum cooling point, the thermostat will cut off current; also, it trips off the compressor when the voltage is low.
FLEXIBLE CABLES: Flexible cables are their copper wire that supplies current from the power source with the help of plug to the air conditioner.
BULB: Bulb is a power indicator, it lights up when the current has entered the air conditioning system.
FOAM THAT COVERS THE INTERNAL BODY: This is a substance which covers the in cover of the air conditioner so as to avoid loss of cool air or escape of cooled air that comes from the evaporator.
SWITCH: The switch controls the current coming into the air conditioning system; that is, it is the key which opens and closes (on and off) the activities of the air conditioner.
FRONT GRILLE: Front grille is used to cover the front part of an air conditioner in other to prevent damages to other components a round it.
FAN MOTORS: It is known as the unit in between the fan blade and the fan blower where the current is produced to drive the fan blade and fan blower.
FAN BLADE: The fan blade is located at the back of the condenser. It blows away hot air from the room.
FAN BLOWER: This can be located at the back of the evaporator system. It blows cool air from the system into the room.
FILTERS: This is an instrument that filters the air in other to prevent the dust in the air from entering the evaporator.
CAPACITOR: The capacitor is a unit used to charge and draw more current; it is also used for starting period in maintaining the lowest mark of change in temperature from hot to cold.
CAPILLARY TUBE/METERING DEVICE: This device is carefully calibrated in length and inside diameter to meet the exact amount of liquid refrigerant flow required for each unit.
FIBER (LAGGING) MATERIAL: This material is mostly made of wool and it is used to prevent the loss of heat in order to maintain the temperature of the air conditioner.

1.9 AIR CONDITIONING SYSTEM/THE PROPERTIES OF AIR
Air is the medium at which an air conditioner works, before we cool or heat it, we have to condition it first; by so doing, it cools or heats a building and makes it s occupants comfortable.
An air conditioning is the complete conditioning of air by heating, cooling, humidifying, dehumidifying, filtering, cleaning and distribution.
All the systems do not require the induction of all these conditioning processes, but each system requires consideration of all the processes. The atmospheric air is composed of (i) Dry air (ii) Moisture in the form of water vapour or s team (iii) impurities such as smoke, dust and toxic gases.
Pure dry air is a moisture of several gases like oxygen, nitrogen and varying amount of carbon (iv) oxide and the inert gases.
PERCENTAGE BY WEIGHT OF AIR
GASES PERCENTAGE IN DRY AIR
NITROGEN
OXYGEN
CARBON DIOXIDE
OTHER GASES 77
22
0.04
0.96