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AC Compressor: How It Works and Replacement Tips

Your AC compressor is the lifeblood of your air conditioner. The compressor is responsible for circulating and pressurizing the refrigerant in your unit, so the refrigerant can carry and release heat. If refrigerant didn’t move throughout your unit and release heat, cold air wouldn’t be produced and your home would remain warm. This means, without the compressor, your unit wouldn’t be able to function.

While it is one of the most important parts of your air conditioner, the compressor can also be one of the most expensive parts to replace. It’s crucial you understand how your AC compressor works and what to look for when you suspect it might be failing, so you can maintain a comfortably cool home all summer long.

The role of the AC compressor

The AC compressor is an essential part of how your air conditioner works. In central air conditioning systems, the unit is split with the air conditioner located outside and its heating counterpart, like an air handler or furnace, located inside. With packaged air conditioners, the entire unit is located outside. When the HVAC unit is located both inside and outside, the air conditioner compressor can always be found in the outdoor portion of the unit, but it should only be inspected by a licensed HVAC professional.

The compressor is powered by a motor, and its main job is to both circulate and apply energy to the refrigerant in the unit. Refrigerant is a chemical cooling compound that absorbs heat and humidity from your home, carries it, and then releases that heat and humidity outside to ultimately cool your home. But, the refrigerant can’t do its job without the compressor.

Refrigerant changes from liquid to gas during its journey through the air conditioner, but when it reaches the compressor, it is in gaseous form. The compressor applies energy to the gaseous refrigerant, or compresses it, so it becomes a high-pressure gas. The compressor also raises the temperature of the refrigerant, so that it’s hotter than the temperature outside. Once the compressor performs these two tasks on the refrigerant, the refrigerant is forced into the condenser coil. Here, it can release all the heat and humidity it’s carrying outside and turn back into a liquid.

Without the condenser, the refrigerant wouldn’t release any heat and humidity from your home to the outside. That means, heat would just circulate throughout your air conditioner and back into your home, resulting in no temperature change at all. Thanks to the compressor, your home can reach your desired temperature quickly and efficiently.

Signs of a failing AC compressor

If your air conditioner compressor fails, your entire air conditioner will fail, resulting in the need for AC troubleshooting. An HVC compressor carries a high voltage so improper handling can result in serious injury or death. Therefore a licensed HVAC technician is the only person to inspect and service a broken compressor, but there are some signs you can look for that indicate it’s time to call a professional. These include, but are not limited to:

  • Unchanging temperatures in your home: If your AC is on, but the temperature in your home isn’t going down, the compressor might not be working properly. If the compressor isn’t releasing hot air outside, it’s getting stuck in your unit and ultimately in your home, making it impossible for the temperature to drop.
  • Lukewarm or cool air is being released outside: The compressor is in the portion of your air conditioning unit located outside. When it’s functioning properly, it should be releasing hot air outside. To detect whether your unit is releasing hot air, go outside while your air conditioner is turned on. Without getting too close to your unit, stand near the outdoor fan. Without actually touching the air conditioner, align your hand with the fan. You should be able to feel a stream of hot air coming out of the air conditioner. If you feel lukewarm or cold air coming out outside, your compressor might not be working.
  • Strange noises coming from your AC: When your unit is turned on and functioning properly, you should hear the fan and compressor running smoothly, with a slight hum. If you hear banging, hissing, clattering or screeching noises, it’s likely that your compressor, or another component of your AC unit, is not working properly and you need to call an HVAC professional.
  • Leaks around your unit: If you go outside and see a leak around your air conditioner, do not go near it. This may be a refrigerant leak, which is a sign that some part of the AC cooling cycle, possibly the AC compressor, is not running smoothly. Refrigerant is a dangerous chemical, and should only be handled by an HVAC professional.

AC compressor replacement: What to consider

If you suspect that your AC compressor might be failing, you’re likely wondering if you should repair it or replace your air conditioner altogether. The first step in this process is to bring in an HVAC professional to ensure it’s your compressor that is broken and that no other parts of your unit are causing issues. After that, here are some things you should consider when you’re thinking about whether you should repair your air conditioner compressor or replace the entire unit:

  • How long you’ve had the unit, and if it’s almost time for a new AC anyway.
  • If your unit is under warranty or not for new parts.
  • The cost of replacing the AC compressor vs. replacing the entire unit.

AC compressor replacement costs

How much it costs to replace your AC compressor depends largely on if your unit is under warranty or not. If your unit is under warranty, an AC compressor replacement can cost $600 to $1,200. If it’s not under warranty the replacement can cost anywhere from $1,300 to $2,500, according to data collected by Home Guide with 9 AC repair companies, reviewed on Oct. 13, 2020.

Keep in mind, sometimes it might be more cost effective to replace your unit entirely if your compressor doesn’t work, especially if your unit is not under warranty. According to the same Home Guide data, a new air conditioner can cost $3,300 to $5,900.

AC compressor maintenance

AC maintenance is NOT a DIY project, and AC compressor maintenance is no exception to that rule. Compressor maintenance should only be handled by an HVAC professional. The main things you can do yourself to maintain your AC unit are to make sure nothing is on top of or blocking your air conditioner that might obstruct it from doing its job, and to regularly change your AC filters as needed.

Beyond that, AC compressor maintenance is to be handled by an HVAC professional. When your technician services your unit, they’ll make sure your compressor and the rest of your unit is running properly. They’ll also clean your condenser coil, which works hand in hand with the compressor to release hot air. With proper maintenance, the AC compressor can last up to 15 years!

Bottom line

The AC compressor is responsible for pressurizing the refrigerant so it’s able to release heat and humidity from your home outside. Without the AC compressor, your air conditioning unit wouldn’t be able to function properly. Home AC compressors can be expensive to replace, so it’s important you get your unit serviced regularly by an HVAC professional and know the warning signs of a broken compressor.

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