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How does Air Conditioning work?

Air conditioners and refrigerators work the same way. Instead of cooling just the small, insulated space inside of a refrigerator, an air conditioner cools a room, a whole house, or an entire business.

Air conditioners use chemicals that easily convert from a gas to a liquid and back again. This chemical is used to transfer heat from the air inside of a home to the outside air.

The machine has three main parts. They are a compressor, a condenser and an evaporator. The compressor and condenser are usually located on the outside air portion of the air conditioner. The evaporator is located on the inside the house.

The working fluid arrives at the compressor as a cool, low-pressure gas. The compressor squeezes the fluid. This packs the molecule of the fluid closer together. The closer the molecules are together, the higher its energy and its temperature.

The working fluid leaves the compressor as a hot, high pressure gas and flows into the condenser. If you looked at the air conditioner part outside a house, look for the part that has metal fins all around. The fins act just like a radiator in a car and helps the heat go away, or dissipate, more quickly.

When the working fluid leaves the condenser, its temperature is much cooler and it has changed from a gas to a liquid under high pressure. The liquid goes into the evaporator through a very tiny, narrow hole. On the other side, the liquid’s pressure drops. When it does it begins to evaporate into a gas.

As the liquid changes to gas and evaporates, it extracts heat from the air around it. The heat in the air is needed to separate the molecules of the fluid from a liquid to a gas.

The evaporator also has metal fins to help in exchange the thermal energy with the surrounding air.

By the time the working fluid leaves the evaporator, it is a  low pressure gas carrying the heath out of the home. It then returns to the compressor to begin its trip all over again.

This continues over and over and over until the room reaches the temperature you want the room cooled to. The thermostat senses that the temperature has reached the right setting and turns off the air conditioner. As the room warms up, the thermostat turns the air conditioner back on until the room reaches the temperature.

What is a heat pump?

Imagine that you took an air conditioner and flipped it around so that the hot coils were on the inside and the cold coils were on the outside. Then you would have a heater. It turns out that this heater works extremely well. Rather than burning a fuel, what it is doing is “moving heat.”

A heat pump is an air conditioner that contains a valve that lets it switch between “air conditioner” and “heater.” When the valve is switched one way, the heat pump acts like an air conditioner, and when it is switched the other way it reverses the flow of the liquid inside the heat pump and acts like a heater.

Heat pumps can be extremely efficient in their use of energy. But one problem with most heat pumps is that the coils in the outside air collect ice. The heat pump has to melt this ice periodically, so it switches itself back to air conditioner mode to heat up the coils. To avoid pumping cold air into the house in air conditioner mode, the heat pump also lights up electric strip heaters to heat the cold air that the air conditioner is pumping out. Once the ice is melted, the heat pump switches back to heating mode and turns off the heat strips.

How do I check for a dirty evaporator coil?

Probably the easiest way is to measure the temperature of the air entering the system at the filter then measuring the temperature at the closest register. A good system will show a 20-25 F degree difference in temperature. A restricted airflow will have a higher differential. If the house does not cool properly even after Freon is freshly added to the system, then the evaporator coil may need cleaning. Dirty coils afe a very common source of inefficient cooling.

What brand do you recommend?

We at Affordable Heating & Air recommends Everest . Everest air conditioners have been declared one of the most energy efficient brands in the industry and have also been getting very good reviews for their  sound insulation which significantly reduces noise levels. Most Everest central air conditioners meet, and in many cases exceed, the energy efficiency requirements set by the Energy Star Program.

What is a BTU?

BTU stands for British Thermal Unit. This the measurement used to describe the cooling capacity, or amount of heat removed from the air, of the air conditioner. It is a measurement worked out according to the amount of cooling needed to lower the temperature of one pound of water by one Fahrenheit degree. One ton of cooling is the equivalent of 12,000 Btu’s/h.


Contractors and government agencies say the biggest mistake consumers make when buying air conditioners is getting a unit with too much capacity. An unscrupulous contractor will sell you an air conditioner with too much capacity because it costs more, but the bigger disadvantage occurs once you own it. It will frequently cycle on and off. This is inefficient and expensive.
Capacity is measured in BTUs (British Thermal Units). The specification is most commonly expressed in tons. Sometimes you’ll see BTUs per hour (a ton equals 12,000 BTUs per hour). A range of two to five tons is typical for a house.

How do I know the contractor is qualified to do the job?

First and foremost, makes sure that the contractor is a legally licensed contractor. By law, all contractors must prominently display their contractor license number on all advertising and business information. If you don’t see it, that can be a warning sign. Heating and air is a fairly complex industry. While it does not guarantee that a contractor is totally competent, it is still a strong indication that the contractor knows what he or she is doing if they have a license.

Other important factors are years of experience and the number of years that the company has been in business. Basically, bad companies tend not to survive if they have a consistent record of bad workmanship,. A company like Affordable Heating & Air with decades of service to the community is usually a safer choice than a company without as track record.

What if I have questions about the bid?

With the word “affordable” in our name, customers sometimes think we are “the cheapest”. This is not the case. Our goal at Affordable Heating & Air is to give our customers the best possible value for the money they are spending to heat and cool their homes. Our prices are fair, and, well, affordable. Our experience has shown that cheap pricing tends to reflect workmanship that attempts to cut corners and attempt to accomplish installations in ways that are not always good for the home or business owner. On the other hand, our representatives are more than happy to discuss any questions that you might have in a clear and friendly manner.

What is EER?

Abbreviation for Energy Efficiency Ratio. This is a measurement of the efficiency of the cooling unit. It is calculated by comparing the Btu’s to the watts of electricity consumed and the higher the efficiency rating the more efficient the unit. This benefits both environment and consumer as less energy is used which results in a lower operating costs.

My air-conditioning stopped cooling, what can I do?

A lot of problems with air conditioning are caused by dirt, so the first thing you can do is trying to clean the unit. . Keep the outside coils as clean as possible. Keep plants from growing against the finned area, keep the exhaust pathway free of obstructions. A dirty inside coil can cause the coil to ice over and the flow of air is reduced. The major cause of dirty inside coils is not changing the filter often enough.

What is a S.E.E.R. Rating?

SEER (or S.E.E.R.) Rating stands for Seasonal Energy Efficiency Rating. It is the rating and performance standards that have been developed by the U.S. government and equipment manufacturer’s to produce an energy consumption rating that is easy to understand by consumers. It has a universal formula and conditioning that can be applied to all units and compensates for varying weather conditions.

Basically, the lower the S.E.E.R. rating, the more energy (electricity) is required to produce the desired effect.

S.E.E.R. of “6” produces about 6 BTU/hr of cooling, per watt of electricity.

S.E.E.R. OF “12” produces about 12 BTU/hr of cooling per watt of electricity. This would be about double the cooling effect of a 6 S.E.E.R. Unit.

Nowadays, energy consumption is a very, very important issue and is sure to remain so for a long time into the future. This increased efficiency has become more and more important as electricity rates continue to rise.

What is a Split-system?

This is an air conditioner that has been split into two units. The outdoor unit contains the condenser and compressor, the indoor unit contains the evaporator coil.

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