Tuesday, July 22, 2008

~SeVen ThInGs YoU ShOuLd KnOw AbOuT aIrCoNd~

With spring here, summer is not that far off. It is time to start thinking about air conditioning. Here are seven things you should know about air conditioning.

1- Air conditioners are made up of two motors, which utilize electrical power. One of them is the compressor, which is the responsible for cooling the air with the refrigerant. The second motor is responsible for moving the air by driving the fan.

2- Your air conditioning costs goes up by about 3% to 4% for every degree that the thermostat is set lower than 78 degrees.

3- Make it a habit to regularly compare the room temperature with the temperature of the air being emitted by the air conditioner. The temperature of the air being emitted by the AC should be approximately 20F lower than the room temperature.

4- An air conditioner effectively dries out the air by converting the water vapor into liquid water. This decreases the humidity and increases the comfort level in the home. In a window unit air conditioner, this water drains out from the rear and in central air conditioning, the water flows to a basement floor drain. Window units have a drip pan at the base and in central air conditioning the drip pan is located beneath the cooling coil, which is inside the ductwork. This drip pan catches the water that flows out and directs it towards the appropriate drain location. Check this water flow. If you can see it going where it is supposed to go, then that’s great. It means your air conditioner is working just the way it is supposed to.

5- You need to make sure that your window units are tilted in such a way that the end that is indoors is higher than the outdoor end so that the water flows outside and not back inside the house ore else you’ll have one enormous mess inside the house. You should also make sure that the water does not drain down the furnace lest the furnace get rusted.

6- Schedule a pre-season maintenance that involves cleaning the drain and the drip pan. Failure to do so could prevent the water from draining. This stagnant water could form ice on the cold coil. As this ice builds up it prevents the outside air from coming in and flowing through the cold coil and thus prevent your air conditioner from functioning efficiently. It could even stop your air conditioner from functioning altogether. As soon as you notice that the air conditioner is not working as efficiently as it should and the house is not cooling down as much as before, you should take immediate action to rectify the situation. This is very easily done- The first thing you should do is turn off the air conditioner. Allow the ice to melt and then fix the drain problem. The AC can now be switched back on.

7- If the air seems to be flowing as it should, but the room does not appear to be getting any cooler, the problem is something other than ice. It could be the level of the refrigerant is low. An air conditioner will keep on running despite low refrigerant levels, but the problem is it does not cool the room down whatsoever. This is a complete waste of electricity.

~HiDe ThIs UgLy ThInG~

You need it. But you don’t have to see it.

Most window A/Cs have slats or sections of bare plastic that can be covered with wrapping, scrapbook, or printed paper. Use spray mount or double-sided tape.

Environmental therapist Matthew Tudor-Jackson designed a lacquered ash cabinet that hides his A/C and all the cords and cables attached to other living-room electronics. Two slatted doors let cool air out.

Prop stylist Lauren Shields made a short café curtain that sits a third of the way up the window just high enough to cover the A/C. She pulls it aside when the unit is on.

Designer Jayne Michaels and furniture dealer Larry Weinberg used vintage holed tiles and an iron frame to create a sculpture that stands on a table before the window.
All you need: a meshlike material
that’s nice to look at and lets air through.

Artist Leslie Fry designed a bas-relief sculpture to fit over her wall-unit A/C. She built a wooden frame, then affixed a cover made from plastic forms found in cookie boxes.

~TiPs FoR bUyInG a NeW aIr CoNdItIoNeR~

  • Don't hire a contractor who wants to size your unit based solely on the floor area of your house. Contractors should calculate how much cooling a home needs according to the guidelines set forth in the Manual J of the Air Conditioner Contractors of America (ACCA). To gather the necessary information, your contractor should spend about an hour poking around your house, taking measurements in each room and asking questions. He or she needs to measure floors, ceilings, and walls--including all the windows--and check insulation in the attic, walls, and crawlspaces. Some other factors that go into the cooling load formula include indoor and outdoor temperatures, number of occupants, shading, and roof color.

  • Insist on getting a copy or computer printout of the cooling load calculations. These can be useful in comparing bids from contractors. Question the contractor if the calculations don't include all the items mentioned above, or if you see anything that you don't understand.

  • Ask your contractor to size the air conditioner based on the latent cooling load (which considers the humidity of the air) as well as the sensible cooling load (which considers the temperature of the air) for your home.

  • Don't be tempted by the lowest bid. Be willing to pay for the time the contractor must spend to do the job right.

  • Check for duct leaks and disconnected ducts. Also be sure air flow is not restricted by ducts that are crushed or too small for the system. Ideally, the contractor should use diagnostic equipment to find leaks and then fix them with quality duct sealants (not duct tape). It doesn't make a lot of sense to buy a larger air conditioner to cool your attic or crawlspace!

  • Buy a high-efficiency unit. New air conditioners are required by federal law to have a SEER of 13 or higher. Even though it will cost more, it's usually worth it to buy at a unit exceeding this value because over time that initial investment will be paid back with energy savings. Look for an ENERGY STAR label when you shop. If you are replacing an existing air conditioner, you must replace the whole unit, including the inside coil and often the blower fan, to achieve the rated efficiency. [Information in this paragraph updated by LBNL to reflect new standards of January 2006]

  • Install for ease of maintenance. Make sure the inside coil can be reached for cleaning. The contractor may have to install an access panel, depending on the model. The coil should be cleaned every two years. The air filter should be located where it is easy to remove. Check it every month during the summer, and clean it or change it whenever it is dirty.

  • Place the outside unit on the north or east side of the house, out of direct sunlight, but don't add shade for it. Leave plenty of room for free air flow on all sides, and leave at least 4 feet of clearance at the top. Keep the area free of debris and shrubbery. The air conditioner draws a lot of air through it. It's more important for the unit to have a lot of space than for it to be well shaded.

Choosing a New Central Air Conditioner

When you buy a new air conditioner, there are three things to remember. Don't buy an oversized unit. Buy an efficient model. And make sure that the unit you buy is installed properly.

Studies show that one third to one half of home air conditioners don't work the way they should because they are oversized. Contractors generally size air conditioners at least a half ton larger than necessary, and often oversize by a ton or more. (We're not talking about the weight of the air conditioner here, but tons of cooling. One ton of cooling is approximately how much cooling you'd get from melting a ton of ice. One ton of cooling is equivalent to about 12,000 Btu of air conditioner capacity.)

An oversized air conditioner turns on and off more often than it should, even during the hottest weather. You pay more for it, and it uses more energy, raising your utility bills. It won't dehumidify the air as well as a smaller system would. It's noisy, especially if the grilles in your house were designed for a smaller unit, as most are. An oversized air conditioner doesn't mean cool comfort for you. It means higher first costs, higher electricity bills, and a home that's uncomfortable to be in.

So make sure that your contractor sizes your air conditioner properly. This should not be done by rule of thumb. Ask your contractor to use the sizing manuals put out by the Air Conditioning Contractors of America (ACCA). Manuals J and S help the contractor size and select equipment; Manual D gives guidance on designing the duct system. The contractor measures your house, notes the window area and the direction the house faces, and measures insulation levels. These data are entered into formulas that are used to calculate the amount of cooling your house needs.

Another important consideration is the ability of the selected air conditioner to remove moisture from the air. Different models have different abilities to handle moisture. The contractor should understand how to pick an air conditioner that is suitable for your house, and for your climate. For more on choosing the best unit for your needs, and on dealing with contractors, see above.

Note: Installation and service charges may be added to these costs.

Source: 1994 Measure Cost Study, California Energy Commission

­Wouldn't it be nice to know how these indispensable machines work their magic?

­ Air conditioners come in various sizes, cooling capacities and prices. One type that we see all the time is the window air conditioner, an easy and economical way to cool a small area:

Window Air Conditioner

People who live in suburban areas usually have one of these in their backyard:

Air Conditioner

If you live in an apartment complex, this is probably a familiar sight:

Air Conditioner

Most businesses and office buildings have condensing units on their roofs, and as you fly into any airport you notice that warehouses and malls may have 10 or 20 condensing units hidden on their roofs:

Air Conditioner

And then if you go around back at many hospitals, universities and office complexes, you find large cooling towers that are connected to the air conditioning system:

Air Conditioner

Even though each of these machines has a pretty distinct look, they all work on the same principles. In this article, we will examine air conditioners -- from small to huge -- so you know more about what you're seeing.

Friday, June 27, 2008

~Air-conditioning Basics~

An air conditioner is basically a refrigerator without the insulated box. It uses the evaporation of a refrigerant, like Freon, to provide cooling. The mechanics of the Freon evaporation cycle are the same in a refrigerator as in an air conditioner. According to the Merriam-Webster Dictionary Online, the term Freon is generically "used for any of various nonflammable fluorocarbons used as refrigerants and as propellants for aerosols."
Air Conditioner Cycle

Diagram of a typical air conditioner

This is how the evaporation cycle in an air conditioner works (See How Refrigerators Work for complete details on this cycle):

  1. The compressor compresses cool Freon gas, causing it to become hot, high-pressure Freon gas (red in the diagram above).
  2. This hot gas runs through a set of coils so it can dissipate its heat, and it condenses into a liquid.
  3. The Freon liquid runs through an expansion valve, and in the process it evaporates to become cold, low-pressure Freon gas (light blue in the diagram above).
  4. This cold gas runs through a set of coils that allow the gas to absorb heat and cool down the air inside the building.

Mixed in with the Freon is a small amount of a lightweight oil. This oil lubricates the compressor.

So this is the general concept involved in air conditioning. In the next section, we'll take a look inside a window unit.

~Air Conditioning~

Just about every modern car, truck or SUV sold these days can be had with air conditioning. It's so common that most people take it for granted. You press the button for air conditioning in your car and — presto! — cold air starts to flow out of the car's vents. It's easy, it's simple, and it's a major convenience. Could you imagine driving to a job interview in Phoenix, Ariz., if your car didn't have air conditioning? By the time you got to your interview, you'd be a sweaty, stinky mess.

Have you ever wondered how the air conditioning in your vehicle works? If you're like most people, you probably haven't. But we're here to educate you painlessly. Air conditioning is the process by which air is cooled and dehumidified. The air conditioning in your car, your home and your office all work the same way. Even your refrigerator is, in effect, an air conditioner. While there are many physical principles that relate to air conditioning, this article sticks to the basics. It explains the general concepts of automotive air conditioning, the components used and what you need to know to keep your car's A/C system working properly.

Did you know that when you turn on the A/C in your car, you are burning extra gasoline to make yourself feel cooler? It's weird to think that by burning something you become cooler, but it's true.

Here's a simple example of evaporation. Imagine that you're swimming around in your neighbor's backyard pool on a summer day. As soon as you get out, you start to feel cooler. Why? The water on your body starts to evaporate and turns into water vapor. And as it evaporates, it draws heat away from your body, and you get goose bumps. Brrr! Now let's say your neighbor hands you a big glass of ice-cold lemonade. You take a sip and set it down on a table. After a minute or two, you notice that water has collected on the outside of the glass. This is condensation. The air surrounding the glass becomes cooler when it encounters the cold glass, and the water vapor the air is carrying condenses into water.

Both of these examples occur at normal atmospheric pressure. But higher pressures can also change a vapor (or a gas) into a liquid. For example, if you look at a typical butane cigarette lighter, you can see liquid inside it. But as soon as you push down on the button, butane gas comes out. Why? The butane is under high pressure inside the cigarette lighter. This high pressure causes the butane to take liquid form. As soon as the butane is released and it encounters normal atmospheric pressure, it turns back into a gas.

OK, those are the basic ideas. But how do they apply to making your car's vents blow cool air? The principles of evaporation and condensation are utilized in your car's A/C system by a series of components that are connected by tubing and hoses. There are six basic components: the compressor, condenser, receiver-drier, thermostatic expansion valve, the evaporator and the life-blood of the A/C system, the refrigerant.

Refrigerant is a liquid capable of vaporizing at a low temperature. In the past, R-12 refrigerant was used in cars. But this chlorofluorocarbon (CFC) is harmful to the earth's ozone layer. Consequently, all vehicles built after 1996 use R-134A, a more environmentally friendly refrigerant.

Here's how an air conditioning system and its components work.

Step One: The compressor is the power unit of the A/C system. It is powered by a drive belt connected to the engine's crankshaft. When the A/C system is turned on, the compressor pumps out refrigerant vapor under high pressure and high heat to the condenser.

Step Two: The condenser is a device used to change the high-pressure refrigerant vapor to a liquid. It is mounted ahead of the engine's radiator, and it looks very similar to a radiator with its parallel tubing and tiny cooling fins. If you look through the grille of a car and see what you think is a radiator, it is most likely the condenser. As the car moves, air flowing through the condenser removes heat from the refrigerant, changing it to a liquid state.

Step Three: Refrigerant moves to the receiver-drier. This is the storage tank for the liquid refrigerant. It also removes moisture from the refrigerant. Moisture in the system can freeze and then act similarly to cholesterol in the human blood stream, causing blockage.

Step Four: As the compressor continues to pressurize the system, liquid refrigerant under high pressure is circulated from the receiver-drier to the thermostatic expansion valve. The valve removes pressure from the liquid refrigerant so that it can expand and become refrigerant vapor in the evaporator.

Step Five: The evaporator is very similar to the condenser. It consists of tubes and fins and is usually mounted inside the passenger compartment. As the cold low-pressure refrigerant is released into the evaporator, it vaporizes and absorbs heat from the air in the passenger compartment. As the heat is absorbed, cool air will be available for the occupants of the vehicle. A blower fan inside the passenger compartment helps to distribute the cooler air.

Step Six: The heat-laden, low-pressure refrigerant vapor is then drawn into the compressor to start another refrigeration cycle.

As you can see, the process is pretty simple. Just about every vehicle's A/C system works this way, though certain vehicles might vary by the exact type of components they have.

The best thing about air conditioning is that all you have to do is press a button to make it work. Air conditioning systems are pretty reliable. On a modern and relatively new vehicle, it is rare to have problems. And if there are problems, they are pretty much one of two things: No cool air or insufficient cool air. If you own an older car and its A/C system doesn't seem to be working properly, here are some general troubleshooting tips:

~No Cool Air~

  • Loose or broken drive belt
  • Inoperative compressor or slipping compressor clutch
  • Defective expansion valve
  • Clogged expansion valve, receiver-drier or liquid refrigerant line
  • Blown fuse
  • Leaking component: any of the parts listed above or one of the A/C lines, hoses or seals
~Insufficient Cool Air~
  • Low refrigerant charge
  • Loose drive belt
  • Slipping compressor clutch
  • Clogged condenser
  • Clogged evaporator
  • Slow leak in system
  • Partially clogged filter or expansion valve
Most A/C repairs are best left to a repair shop. Recharging the refrigerant, in particular, requires special equipment that most people don't own. There are a couple things you can do, however. First, make sure to have the system checked regularly according to your vehicle's owner's manual. Second, if you live in a place with a cold climate, it might not make much sense to run the A/C during the winter months, but many shop technicians recommend running your A/C system regularly, because it contains a light mineral oil in the refrigerant to keep the compressor properly lubricated. The general rule of thumb is 10 minutes per month. Some heating, ventilation and air conditioning systems also engage the A/C compressor for defrost mode (for example, most GM vehicles).

See more product announcements for Industrial Fans and Industrial Blowers
Pressure Blowers

~Pressure Blowers ~

Unit Heaters

~Unit Heaters ~

FRP-General-Purpose Fume Exhausters

FRP-General-Purpose Fume Exhausters

Selecting Air Conditioner Components

Split system air conditioners contain various components that must be matched up accordingly. We have a special Kit Builder to help you select all the right components.

In a split system, the compressor and condenser coil (contained in a standard unit or heat pump), are installed outside the home, and the evaporator coil is installed inside the home in the plenum of a forced-air furnace or air handler. The indoor and outdoor components of a split-system are usually connected by two refrigeration lines and a low-voltage relay cable.

The following components make up a split system:

Goodman air conditioner Standard Unit (Condenser) or Heat Pump

A condensing unit is the main component of central air conditioning, and is the part that sits outside the home. Inside it is a pump called a compressor, coils, fan and electrical system. The condenser comes entirely pre-assembled and pre-charged with Freon.

When a standard air conditioning system (with a condensing unit) is operated, the condenser in the yard gets warm and the evaporator coil in the furnace gets cold, thereby cooling the home in summer.

With a heat pump, the same happens in summer, but in winter, the reverse occurs: the outside condenser gets cold and the inside evaporator coil inside the air handler gets warm, thereby heating the home. Heat pumps work best in climates where winter temperatures do not regularly fall below 25 degrees Fahrenheit. Most homes in central and northern states use standard systems, and in the south, both standard and heat pumps are popular.

Evaporator Coils

An evaporator coil is the part of an air conditioning or heat pump system that becomes cold when the unit operates. It is connected to the ductwork of the home. When the system is on, air flows through the coil and the cold air is distributed throughout the home.

Evaporator coils are either cased or uncased and must be matched up with the condensing unit or heat pump to ensure proper operation of your air conditioning system. You will need only one of the following three types:

Cased Evaporator Coils

Cased evaporator coils are used primarily if you are purchasing a new furnace. Cased coils and furnaces sold on our site must be matched up for an exact fit.

Horizontal Evaporator Coils

Horizontal evaporator coils are used when you have a furnace that is mounted horizontally.

Uncased Evaporator Coils

Uncased evaporator coils are used primarily if you already have a furnace and will be inserting the coil in your pre-existing ductwork.

Condensing Unit Pad

Pads are simply a base for the outdoor air conditioner or heat pump to sit on. They are made of 2-inch thick plastic and are very rigid. The plastic is made with ultraviolet inhibitors so it will not break down in sunlight. Pads come in different sizes, fitted for your particular condensing unit or heat pump.

Electrical Disconnect

A disconnect is a safety on/off electrical switch mounted on the home near the condenser or heat pump. It is required by electrical code, and is a good idea for safety and system servicing purposes.

Refrigerant Line Sets

Line sets consist of two semi-flexible copper pipes to connect the outdoor air conditioner or heat pump to the indoor evaporator coil. The smaller pipe is called the liquid line. The larger pipe is referred to as the suction line and includes insulation. The liquid line diameter for all systems is 3/8 inches in diameter. The suction line diameter will be either 3/4, 7/8 or 1 1/8 inches, depending on the size and efficiency of the air conditioner or heat pump. Line sets come in several lengths and are designed to be cut to fit your exact needs.

Electrical Whips

Electrical whips are simply wires in a weatherproof casing for outdoor use. They are used to connect the 220-volt power to your outdoor air conditioner or heat pump. A typical installation requires two electrical whips. Whips come in two wire size thicknesses (gauges), No. 10 Gauge or No. 8 Gauge and are used depending on which system size and efficiency you choose.

Installation Supplies Packages

Alpine Home Air Products Supplies Packages make your air conditioning or heat pump installation easy! They include nearly all the miscellaneous materials needed for the job. If you are using an uncased evaporator coil, choose a supplies package that also contains pre-fabricated sheet metal for a fast and easy coil installation. All supplies packages include our exclusive 1-hour installation instructional video that clearly shows you how to install your own air conditioning system successfully.

~CaR aIr CoNdItIoNiNg SyStEm SeRvIcE~

L V V Services offer a fully mobile vehicle air conditioning Repair and Regas service; we are based in Bridgend, South Wales and cover an area from Newport to Swansea along the M4 corridor and the surrounding area.

Air conditioning system operation
Air Conditioning

Air conditioning is a system used to create and maintain a comfortable driving environment inside a vehicle. It does this by transferring the heat from inside a vehicle to the outside keeping the temperature down inside the car.The system cools, dries and cleans the air.

The most basic systems have manual temperature control but systems are becoming more and more complex with full climate control on a lot of modern cars which rely on a lot of sensors to maintain the selected temperature.

Air conditioning system schematic diagram-basic system

Air Conditionaing

Common Air conditioning problems
Air conditioning system not cold enough
The Air Conditioning system in your vehicle is not usually covered by most manufacturers servicing schedules and the refrigerant gas that is used to operate the system depletes over time. On average most vehicles lose up to 15% per annum this problem can be caused when then system is not used during the winter months allowing the small “O” ring seals to dry out resulting in a gradual deterioration in system performance eventually resulting in the system being too low to operate at all.

Most problems of this type can be put right fairly easily by a leak check of your system followed by a complete refill of your air conditioning refrigerant, this is sometimes referred to as a re-gas. Please contact us for your air con annual service or re-gas if you live in the Cardiff,Swansea, Bridgend or Newport area.

Air conditioning system smells odd
If you notice any strange smells when you put your air-con on then this could be signs of bacteria build up on your system.

Don’t suffer any longer air con systems can be treated effectively with an anti-bacterial treatment that destroys the bacteria growth and leaves your car smelling fresh again.

Please call for a quote. from one of our mobile air con repair technicians.

Some noises could be early symptoms of a compressor failure (the compressor is the air conditioning pump).The compressor is usually the most expensive part on the system ranging from approximately £230 to £600+ and if the bearings in your compressor break down or if the compressor seizes up it also means that other components can become contaminated with metal particles A flush of the system would then be needed as well as replacement of the compressor, the receiver / drier and the expansion valve - quite a hefty repair bill!

Its not all bad news however - some noises are quite normal

There are 2 different types of air-con system operation some vehicles use a system where the compressor (pump) cycles on and off which means that there is a clicking noise heard every few seconds this is normal, however if this switching cycle changes noticeably or the air con is not very efficient this could be an early symptom of low refrigerant or low gas pressure.

Pool of water underneath the car after using air-conditioning

You will sometimes see a water puddle on the ground, usually under the passenger footwell area, this is a normal feature of the air conditioning system as it is only water dripping from the air conditioning evaporator which has a drain tube fitted to allow the condensation from the evaporator to drain away from the vehicle.

Damp carpet in the footwell or excessive misting of the windscreen

Sometimes the drain tube from the evaporator may become blocked or detached allowing the condensation to build up inside your evaporator if this occurs water will just build up inside your car to a point where there are damp carpets or misting / high humidity type problems.

These are usually fairly easy to resolve. just remember our specialist air con repair technicians are only a phone call away in and around the south Wales area.

AC Control Panel

Today, as we drive our automobiles, a great many of us, can enjoy the same comfort levels that we are accustomed to at home and at work. With the push of a button or the slide of a lever, we make the seamless transition from heating to cooling and back again without ever wondering how this change occurs. That is, unless something goes awry.

Since the advent of the automotive air conditioning system in the 1940's, many things have undergone extensive change. Improvements, such as computerized automatic temperature control (which allow you to set the desired temperature and have the system adjust automatically) and improvements to overall durability, have added complexity to today's modern air conditioning system. Unfortunately, the days of "do-it-yourself" repair to these systems, is almost a thing of the past.

To add to the complications, we now have tough environmental regulations that govern the very simplest of tasks, such as recharging the system with refrigerant R12 commonly referred to as Freon® (Freon is the trade name for the refrigerant R-12, that was manufactured by DuPont). Extensive scientific studies have proven the damaging effects of this refrigerant to our ozone layer, and its manufacture has been banned by the U.S. and many other countries that have joined together to sign the Montreal Protocol, a landmark agreement that was introduced in the 1980's to limit the production and use of chemicals known to deplete the ozone layer.

Now more than ever, your auto mechanic is at the mercy of this new environmental legislation. Not only is he required to be certified to purchase refrigerant and repair your air conditioner, his shop must also incur the cost of purchasing expensive dedicated equipment that insures the capture of these ozone depleting chemicals, should the system be opened up for repair. Simply put, if your mechanic has to spend more to repair your vehicle - he will have to charge you more. Basic knowledge of your air conditioning system is important, as this will allow you to make a more informed decision on your repair options.

Should a major problem arise from your air conditioner, you may encounter new terminology. Words like "retrofit" and "alternative refrigerant" are now in your mechanics glossary. You may be given an option of "retrofitting", as opposed to merely repairing and recharging with Freon. Retrofitting involves making the necessary changes to your system, which will allow it to use the new industry accepted, "environmentally friendly" refrigerant, R-134a. This new refrigerant has a higher operating pressure, therefore, your system, dependant on age, may require larger or more robust parts to counter its inherent high pressure characteristics. This, in some cases, will add significantly to the final cost of the repair. And if not performed properly, may reduce cooling efficiency which equates to higher operating costs and reduced comfort.

AC Flow DiagramVehicles are found to have primarily three different types of air conditioning systems. While each of the three types differ, the concept and design are very similar to one another. The most common components which make up these automotive systems are the following:

COMPRESSOR, CONDENSER, EVAPORATOR, ORIFICE TUBE, THERMAL EXPANSION VALVE , RECEIVER-DRIER, ACCUMULATOR. Note: if your car has an Orifice tube, it will not have a Thermal Expansion Valve as these two devices serve the same purpose. Also, you will either have a Receiver-Dryer or an Accumulator, but not both.

For more information on Air Conditioning, check out The Automotive Air Conditioning Information Server


Commonly referred to as the heart of the system, the compressor is a belt driven pump that is fastened to the engine. It is responsible for compressing and transferring refrigerant gas.

The A/C system is split into two sides, a high pressure side and a low pressure side; defined as discharge and suction. Since the compressor is basically a pump, it must have an intake side and a discharge side. The intake, or suction side, draws in refrigerant gas from the outlet of the evaporator. In some cases it does this via the accumulator.

Once the refrigerant is drawn into the suction side, it is compressed and sent to the condenser, where it can then transfer the heat that is absorbed from the inside of the vehicle.


This is the area in which heat dissipation occurs. The condenser, in many cases, will have much the same appearance as the radiator in you car as the two have very similar functions. The condenser is designed to radiate heat. Its location is usually in front of the radiator, but in some cases, due to aerodynamic improvements to the body of a vehicle, its location may differ. Condensers must have good air flow anytime the system is in operation. On rear wheel drive vehicles, this is usually accomplished by taking advantage of your existing engine's cooling fan. On front wheel drive vehicles, condenser air flow is supplemented with one or more electric cooling fan(s).

As hot compressed gasses are introduced into the top of the condenser, they are cooled off. As the gas cools, it condenses and exits the bottom of the condenser as a high pressure liquid.


Located inside the vehicle, the evaporator serves as the heat absorption component. The evaporator provides several functions. Its primary duty is to remove heat from the inside of your vehicle. A secondary benefit is dehumidification. As warmer air travels through the aluminum fins of the cooler evaporator coil, the moisture contained in the air condenses on its surface. Dust and pollen passing through stick to its wet surfaces and drain off to the outside. On humid days you may have seen this as water dripping from the bottom of your vehicle. Rest assured this is perfectly normal.

The ideal temperature of the evaporator is 32° Fahrenheit or 0° Celsius. Refrigerant enters the bottom of the evaporator as a low pressure liquid. The warm air passing through the evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. This heat is then carried off with the refrigerant to the outside of the vehicle. Several other components work in conjunction with the evaporator. As mentioned above, the ideal temperature for an evaporator coil is 32° F. Temperature and pressure regulating devices must be used to control its temperature. While there are many variations of devices used, their main functions are the same; keeping pressure in the evaporator low and keeping the evaporator from freezing; A frozen evaporator coil will not absorb as much heat.


Controlling the evaporator temperature can be accomplished by controlling refrigerant pressure and flow into the evaporator. Many variations of pressure regulators have been introduced since the 1940's. Listed below, are the most commonly found.


The orifice tube, probably the most commonly used, can be found in most GM and Ford models. It is located in the inlet tube of the evaporator, or in the liquid line, somewhere between the outlet of the condenser and the inlet of the evaporator. This point can be found in a properly functioning system by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. You should then see small dimples placed in the line that keep the orifice tube from moving. Most of the orifice tubes in use today measure approximately three inches in length and consist of a small brass tube, surrounded by plastic, and covered with a filter screen at each end. It is not uncommon for these tubes to become clogged with small debris. While inexpensive, usually between three to five dollars, the labor to replace one involves recovering the refrigerant, opening the system up, replacing the orifice tube, evacuating and then recharging. With this in mind, it might make sense to install a larger pre filter in front of the orifice tube to minimize the risk of of this problem reoccurring. Some Ford models have a permanently affixed orifice tube in the liquid line. These can be cut out and replaced with a combination filter/orifice assembly.


Another common refrigerant regulator is the thermal expansion valve, or TXV. Commonly used on import and aftermarket systems. This type of valve can sense both temperature and pressure, and is very efficient at regulating refrigerant flow to the evaporator. Several variations of this valve are commonly found. Another example of a thermal expansion valve is Chrysler's "H block" type. This type of valve is usually located at the firewall, between the evaporator inlet and outlet tubes and the liquid and suction lines. These types of valves, although efficient, have some disadvantages over orifice tube systems. Like orifice tubes these valves can become clogged with debris, but also have small moving parts that may stick and malfunction due to corrosion.


The receiver-drier is used on the high side of systems that use a thermal expansion valve. This type of metering valve requires liquid refrigerant. To ensure that the valve gets liquid refrigerant, a receiver is used. The primary function of the receiver-drier is to separate gas and liquid. The secondary purpose is to remove moisture and filter out dirt. The receiver-drier usually has a sight glass in the top. This sight glass is often used to charge the system. Under normal operating conditions, vapor bubbles should not be visible in the sight glass. The use of the sight glass to charge the system is not recommended in R-134a systems as cloudiness and oil that has separated from the refrigerant can be mistaken for bubbles. This type of mistake can lead to a dangerous overcharged condition. There are variations of receiver-driers and several different desiccant materials are in use. Some of the moisture removing desiccants found within are not compatible with R-134a. The desiccant type is usually identified on a sticker that is affixed to the receiver-drier. Newer receiver-driers use desiccant type XH-7 and are compatible with both R-12 and R-134a refrigerants.


Accumulators are used on systems that accommodate an orifice tube to meter refrigerants into the evaporator. It is connected directly to the evaporator outlet and stores excess liquid refrigerant. Introduction of liquid refrigerant into a compressor can do serious damage. Compressors are designed to compress gas not liquid. The chief role of the accumulator is to isolate the compressor from any damaging liquid refrigerant. Accumulators, like receiver-driers, also remove debris and moisture from a system. It is a good idea to replace the accumulator each time the system is opened up for major repair and anytime moisture and/or debris is of concern. Moisture is enemy number one for your A/C system. Moisture in a system mixes with refrigerant and forms a corrosive acid. When in doubt, it may be to your advantage to change the Accumulator or receiver in your system. While this may be a temporary discomfort for your wallet, it is of long term benefit to your air conditioning system.