The warm air inside your home is drawn into the system through return ducts and then go over a refrigerant coil. As the warm air is blown across the cooled coil, heat is removed. Refrigerant lines then carry the heat outside. Now you’re left with cool, comfortable indoor air that you can enjoy on the hottest of days. And that’s pretty much it. Sure, the equipment is more complex than that, but the process itself is easy to break down and comprehend.
"Very impressed. Returned call within 24 hours. They came out the same day I spoke with them and made the repair within 25 minutes. Very low service call fee. I had another repair service out two weeks earlier and after 3 service calls and the central air still not fixed and temperatures in the high 90's, it was such a relief to have a company identify the problem, have the necessary part with them and fix the problem."
A split system is a combination of an indoor air handling unit and an outdoor condensing unit. The indoor air handling unit contains a supply air fan and an air-to-refrigerant heat exchanger (or cooling coil), and the expansion device. The outdoor condensing unit consists of a compressor and a condenser coil. Split-systems are typically found in residential or small commercial buildings. These systems have the highest energy efficiency rating (EER) of all the available AC systems. Manufacturers are required to take the EER rating a step further and provide a seasonal energy efficiency rating (SEER) for use by consumers. SEER ratings vary widely and range from 10 to 20. The higher the SEER rating, the more efficient the AC system operates. If heating is required, an alternate method of heating the interior of the building must be used, usually in the form of electric or gas heating. 

A pinging or popping sound coming from the duct work can come from thermal expansion—the ductwork expanding and contracting as it heats and cools.  Or, air blowing past a loose flap of metal can make the sound. Track along the duct runs, listening for the sound. If you locate it, make a small dent in the sheet metal to provide a more rigid surface that’s less likely to move as it heats and cools.
The Chartered Institution of Building Services Engineers is a body that covers the essential Service (systems architecture) that allow buildings to operate. It includes the electrotechnical, heating, ventilating, air conditioning, refrigeration and plumbing industries. To train as a building services engineer, the academic requirements are GCSEs (A-C) / Standard Grades (1-3) in Maths and Science, which are important in measurements, planning and theory. Employers will often want a degree in a branch of engineering, such as building environment engineering, electrical engineering or mechanical engineering. To become a full member of CIBSE, and so also to be registered by the Engineering Council UK as a chartered engineer, engineers must also attain an Honours Degree and a master's degree in a relevant engineering subject.
A number of other variables can influence your decision on whether to repair or replace your furnace, as well. In addition to cost and brand, consider the expected lifetime of your furnace. If it is more than 15 years old, it might make more sense to invest in a new unit even if it costs more than simply repairing the current problem. Long-term costs also play into the equation. For example, your new furnace may be more energy efficient than the current unit. Even though you will pay more for the actual installation, you might be able to make back your investment through lower energy bills. To make your decision, consult with a reliable professional on what to do. In inspecting your furnace, they will be able to make an informed recommendation that looks not just to the next year, but years into the future. That way, you can make the best possible decision for your home and budget long-term.
Air conditioning is common in the US, with 88% of new single-family homes constructed in 2011 including air conditioning, ranging from 99% in the South to 62% in the West.[50] In Canada, air conditioning use varies by province. In 2013, 55% of Canadian households reported having an air conditioner, with high use in Manitoba (80%), Ontario (78%), Saskatchewan (67%), and Quebec (54%) and lower use in Prince Edward Island (23%), British Columbia (21%), and Newfoundland and Labrador (9%).[51] In Europe, home air conditioning is generally less common. Southern European countries such as Greece have seen a wide proliferation of home air-conditioning units in recent years.[52] In another southern European country, Malta, it is estimated that around 55% of households have an air conditioner installed.[53] In India AC sales have dropped by 40%[clarification needed] due to higher costs and stricter energy efficiency regulations.[54]
If the condenser coils are clogged, the compressor can overheat and shut down. You’ll experience intermittent periods of minimal cooling, followed by no cooling. Even if you’re “sure” the condenser coils are clean, clean them again. Turn off the power. Flip the air conditioning service and furnace circuit breakers in your main electrical panel to the “Off” position. Next, turn off the power switch right at the furnace or air handler. Then yank the disconnect block (Photo 1) and clean the condenser coils (Photo 2). If the air conditioning service still doesn’t work properly after you’ve cleaned the condenser coils, installed a new filter and opened all the supply vents, proceed with the following repairs.
*We work on all brands: Adams, Aire-Flo, Amana, Arcoaire, Armstrong, Beutler, Bryant, Carrier, Centurion, Coleman, Comfortmaker, Cozy, Daikin, Day & Night, Dayton, Ducane, Emerson, Empire, Evcon, Fedders, Friedrich, Frigidaire, Fujitsu, Gaffers & Statler, General Electric, Gibson, Goldstar, Goodman, GMC, Haier, Heil, Honeywell, Intertherm, Janitrol, Kenmore, Lennox, Luxaire, Maytag, Mitsubishi, Payne, Rheem, Ruud, Samsung, Sanyo, Sears, Sharp, Spartan, Tappan, Tempstar, Thermal Solutions, Trane, Utica, Weatherking, Westinghouse, Whirlpool, Williams, York, and Zephyr.

Installing or replacing central air can be a huge expense, so you’ll want to get it right. To ensure that you have the best advice, we surveyed more than 14,000 Consumer Reports readers about new central air-conditioning systems they bought and installed between 2009 and 2016. We learned how satisfied they were overall with their purchase, the cost of repairs, how many systems break, and which parts break most often.

While there's nothing you can do to guarantee your air conditioner or furnace will never need repairs, there are ways to take better care of your system. Changing out the air filters every 3-6 months, making sure nothing is obstructing or interfering with the outside unit, and keeping all vents unblocked in well-used rooms will help keep your air conditioning and heating system operating efficiently.

Furnace RepairCompany