• Matt Weber

How an Air Conditioner Works

As the weather warms up, the average homeowner turns their thoughts to that old standby -- the air conditioner. At least, we hope it's on standby, because when the air condition stops working, the house quickly gets hot and stuffy.


Air conditioners draw in warm air from the home and pass it over an evaporator coil that absorbs heat and removes humidity, which cools the air. The AC unit then expels the heat outside and pushes the cold air back into the room to make the temperature more comfortable.

To achieve this procedure, most air conditioners contain the following parts:

  • Condenser coil

  • Compressor

  • Metering Device, such as an expansion valve

  • Condenser Fan

  • Blower

  • Electrical components

  • Evaporator coil or “A” coil

  • Furnace or Air Handler (central air conditioners only)

If any of these parts break or work inefficiently, your AC unit may need repairs or replacement.


Air Conditioner Maintenance Basics

A broken, underperforming or malfunctioning home cooling system in the peak heat of summer is frustrating. Before you call a service technician about your unit, there are several basic maintenance and diagnostic steps you can perform. Knowing what’s wrong with your air conditioner is half the battle. The experts at Enercare, offer the following tip to address common AC problems.


Old Age

The average central air conditioner lasts about 15 years. If your unit is showing signs of old age, like poor performance or unusual noises, it’s likely time for a replacement.


Frozen Coils

If your evaporator coils don't get adequate airflow or they are clogged they can freeze and your AC unit may stop working. Dirt and other types of debris can clog the air filters and ducts, which restricts warm air from reaching the coils. Without the warm air, the coils can’t cool the air being pushed through your AC unit efficiently and may eventually freeze.

If your coils are frozen, you may notice:

  • Warm air coming out of the vents, despite the AC unit being on

  • Condensation or ice on the AC unit or the outdoor refrigerant line

  • Obvious signs of ice on the coil after opening the air handler

If you discover a frozen coil, don’t try to clear the ice by hand because you may damage the unit. Instead, you can use a do-it-yourself remedy to thaw the ice before consulting with an HVAC technician. If the following steps don’t resolve your problem, we suggest you contact an AC expert. You may have a more serious malfunction, like a refrigerant leak, which must be handled by a licensed professional.

  1. Turn off the AC system using the external (wall) thermostat and make sure to turn off the unit using the furnace switch.

  2. Replace any dirty air filters.

  3. Open the furnace or air handler’s panel.

  4. Let the ice thaw naturally. Having the fan run can cause damage to the blower motor and the circuit board.

  5. After the coil has thawed (this may take 24 hours or more depending on how much ice buildup there is), reseal your unit.

  6. Turn on the power by turning on the furnace switch and adjusting the thermostat to come on and wait for your home to cool. If the home reaches the desired temperature and the AC unit turns off, you’ve probably solved the problem. If this doesn’t happen, consult an HVAC technician.

Refrigerant Leak

Refrigerant is the chemical found within the coils that helps cool the air, and without it your air conditioner won’t work. Refrigerant exposure can be dangerous, so if you have a leak (or suspect one) it’s crucial to contact an expert.

If you have a refrigerant leak you may notice:

  • A loss in cooling power

  • Air vents not blowing cold air

  • Hissing sounds coming from your AC unit

  • Frozen evaporator or condenser coils

  • Unusually high AC-related electric bills

Overworked Capacitors and Contactors

If your AC unit isn’t blowing air, you may have a capacitor or contractor issue. Capacitors and contactors work to keep essential motors running in the unit, such as the fan motor and blower motor. The parts require a significant amount of electricity to run, so they tend to get overheated and overworked during hot summer months — especially on older AC units.


Defective Thermostat

Sometimes the unit is not working due to other parts of the HVAC system, like a faulty thermostat. If the thermostat is not working properly, it may give the AC unit wrong information, which causes it to run when it shouldn’t or not turn on when it should.


If you want to read more AC troubleshooting insights and selection information? Then check out Enercare's blog post, The 2021 Definitive Buyer's Guide to Air Conditioners.

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