Central Air Conditioner Parts: Costs and Components

An overview of key central air conditioner parts, including descriptions and cost for brands including Carrier, Rheem, and Trane

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Creating cool air is no simple task. Just ask nature, which has long had a monopoly on the ability to perform the task. Air conditioners don’t create cool air--they displace heat--but they’re about the nearest any man-made technology has come to what only nature can do. Therefore, as you might predict, there are a great number of small, precise, and expensive parts that make up a central air conditioner. These range from small capacitors contained in nearly any electrical device to an air conditioner’s primary workhorse, the compressor. The following is a rundown of these parts, including descriptions and predicted cost.

Primary Central Air Conditioner Parts

Compressor

The compressor, as previously noted, is the workhorse of all the central air conditioner parts. The entire process of displacing heat begins with the compressor, which pressurizes the refrigerant (most people think of Freon when they think of the refrigerant, but Freon has been replaced by more environmentally friendly hydrofluorcarbons). The pressurization drops the refrigerant’s volume, which transforms the refrigerant into vapor. The compressor forces this vapor toward the condenser.

Should You Replace?

Experts recommend only replacing the compressor if it's covered by the manufacturer's warranty. Think of it like a car engine: once the engine goes, it's usually best to replace the car rather than pay for a new engine. If a compressor is not covered by a warranty, it's generally best to replace the unit entirely. Usually, you'll get a more efficient unit with a 10-year warranty that costs little more than a compressor replacement.

Condenser Coil

By the time the vapor arrives at the condenser coil, another key central air conditioner part, it will have soaked up enough warmth to become superheated. Here, in the condenser, the vapor collides with the outside air. Because the vapor will be hotter than the outside air, the heat carried in the vapor is transferred into the outside atmosphere, away from your home.

Should You Replace?

Unfortunately, you don't have a choice. If the condenser coil dies, you'll need to replace the entire air conditioning unit.

Evaporator Coils

Following the transfer of heat, the refrigerant is sprayed into a small pipe, at which time a thermodynamic reaction occurs. Because the refrigerant has a large surface area but minimal volume in its current state, it cools and transforms into a liquid. Here, the evaporator takes over. The liquid collides with the evaporator coils, and mixes with the hot air in the building. While on the evaporator coils, the refrigerant sucks up moisture and heat. The moisture becomes condensation and drips down a drain. What’s left is cool, arid air circulating throughout the building.

Should You Replace?

Evaporator coils cost a minimum of $500 wholesale. Depending on how tricky the installation may be, labor can cost hundreds of dollars or more. The decision, therefore, comes down to the age of the unit. It's often wiser to spend the money for a new unit if your system is aging, thereby boosting your efficiency and offering a new 10-year warranty.

Secondary Central Air Conditioner Parts

Note that besides air filters and coil fins, repairs using the other parts listed below will need expert handling, and therefore labor costs must be considered.

Air filter

Air filter aren’t as much central air conditioner parts as they are a key additions to a central air conditioner. Your air conditioner doesn’t necessarily need one to operate, but without one the system can be damaged and your house filled with unwanted particles. Filters block out dust, pollen, and other nasty particles from entering your home through the air ducts. Some are reusable and some are disposable. Most experts recommend homeowners change the filter monthly when the air conditioner is in peak use. Filters should be replaced every six months during season when they’re not in use. Old filters can reduce energy efficiency by 15 percent.

Cost: Whether Trane, Carrier, Rheem, or another brand, filters cost anywhere from $3 to $20 and come in standard sizes.

Coil fins

Aluminum fins on the evaporator and condenser coils can bend over time, which blocks air flow. Generally, these do not need to be replaced. Air conditioning contractors and dealers sell a special tool called a fin comb that can push the fins back into place.

Cost: Coil fin combs are about $10 to $20.

Contactor relays

Contactors turn on the fan and compressor and kick on when the temperature falls below the thermostats set level.

Cost: About $90 to $180 for parts for Trane, Carrier, Rheem, and other popular brands.

Time delay

The time delay protects the contactor from power surges and short cycling by detecting unusual patterns, such as outages during storms, and forcing a time delay between when the contactor kicks on and off.

Cost: About $90 for parts for Trane, Carrier, Rheem, and other popular brands.

Compressor power pack

Power packs can revive a seemingly dead compressor at a far less expensive price than a new unit.

Cost: About $95 for parts for Trane, Carrier, Rheem, and other popular brands.

Other Parts

Of course, there are countless other parts that make up an air conditioner, from the smallest screws to the drain channels. The above listed parts, however, should cover a wide range of air conditioning repair needs.

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