Your home AC compressor is a device inside the condenser unit that is responsible for extracting the heat from the refrigerant. It also raises the pressure of the vapor by compressing it, hence the name “compressor.” There are several different types of compressors, and they can all go bad at some point.
When an AC compressor goes bad, your system will not function properly, if at all. How do you know if the compressor is the problem? This article will help you determine if the AC compressor has gone bad and if you should repair it or replace it. We will also cover the estimated costs for replacing your home air conditioner compressor.
How AC Compressors Work
Secondarily it also lowers the temperature of the refrigerant to allow the AC system to cool and remove the excess heat from the system and your home.
When the refrigerant leaves the evaporator unit, it has low pressure and is extremely hot. Regardless of the ambient temperature outside, the refrigerant going into the condenser unit is hotter. This causes a heat exchange as the heat is transferred from the coils to the air outside.
The compressor then takes the low-pressure vapor and compresses it, creating a high-pressure vapor. As the high-pressure vapor cools, it is then drawn through the system due to the physics of pressure change. This cycle is repeated as the compressor receives low-pressure refrigerant and cools and condenses it for a return trip through the system.
Types of AC Compressors
As we mentioned above, there are several different types of AC compressors. Let’s take a look at the common types found in your home AC systems.
Single-Stage vs Two-Stage
Single-stage compressors are the most frequently encountered in the US. They have a single operation: on. When they turn on (the inside temperature rises above the set temp on the thermostat), they run at full capacity until the internal temperature falls to the set range.
When the temperature is reached, the compressor shuts off and waits until the temp rises again. With a dual-stage compressor, they have two operation modes: low and high. They are a smarter system, and, based on the internal temperature will choose which mode to run in.
When it is needed, the compressor will run at full capacity like the single-stage unit. However, they will run at low speed to maintain the temperature longer. This means they will run longer but at a lower capacity, helping reduce humidity in the home better than a single-stage compressor.
A reciprocating compressor works similar to a car engine. It has valves, cylinders, and pistons. When the compressor turns on, the pistons begin to reciprocate or move up and down inside the cylinders. The suction valve allows refrigerant to enter the cylinder chamber, and as the piston rises, it compresses the vapor causing the pressure to rise.
When the pressure exceeds the pressure of the discharge valve, the valve opens, and the high-pressure vapor runs through the system to the evaporator. The entire cycle repeats as long as needed to cool the home to the desired temperature.
Not only are scroll compressors more efficient, but they also allow for liquid to enter the chamber, which can cause any other type of compressor to fail.
Scroll compressors are comprised of two perfect conical spirals interlocked together.
The first spiral is permanently mounted inside the compression chamber while the other is floating.
When energized, the floating spiral vibrates and spins inside the other, creating a varying degree of chamber space between the walls of the two spirals.
As the vapor moves through the ever-tightening spirals towards the center, it is compressed, and the pressure is increased. By the time the vapor reaches the center of the spirals, it is a high-pressure vapor and escapes through the discharge port.
A screw compressor, also known as a rotary screw compressor, uses two counter-rotating screws to compress the vapor. As the screws turn, they act as a type of interlocking gears. The low-pressure vapor is introduced at the larger end and is compressed as it is screwed towards the smaller end.
The high-pressure vapor is then released through the discharge valve, and the cycle repeats. Screw compressors aren’t usually found in homes as they are designed for massive airflow (up to 20 tons). However, the efficient use and minimal vibration are making their way to larger homes where two compressors used to be needed.
A rotary compressor works similarly to the reciprocating compressor. It has a cylinder with suction and discharge valves. However, a rotary compressor doesn’t have a piston that moves up and down. Instead, it has a roller that rotates inside the cylinder, blocking off either the suction or discharge valve as it progresses.
When the suction valve is not blocked, the refrigerant enters the chamber. As the roller rotates, it increases the pressure of the vapor, which is then released through the discharge valve as it is exposed. Since the roller rotates in the same direction, the refrigerant is continuously being pulled in, compressed, and pushed out. This cycle repeats as long as the compressor is active.
Centrifugal compressors are highly efficient but are challenging to maintain in a residential setting. Because they must have an exact range of operation, you won’t find very many being used in homes.
These use a piston and cylinder to draw in the refrigerant. An impeller spins, causing the refrigerant to gain velocity, raising its pressure. As the pressure increases, the refrigerant is moved to the discharge valve where it is expelled into the system, and the low-pressure refrigerant is pulled in to start the process over again.
Choosing Replacement Compressors
When it comes time to repair or replace your compressor, there are several factors to consider. Let’s take a look at those factors now.
Identify Compressor Problems
Before you replace the entire compressor or condensing unit, you should check all of the common fault areas first.
If you determine it is the compressor that needs to be replaced, you can move down this list. Compressor repairs aren’t common since most parts are sealed and internal.
If the external or non-sealed parts are found to be at fault, you can replace those parts only. However, in most cases, a complete compressor replacement will be in order.
Type of Compressor
The first thing you need to do is determine which type of compressor you have. In most cases, you will have a single-stage or reciprocating compressor. Once you know the kind of compressor you have, you can get the rest of the information needed (see below) to find the correct replacement.
Compressors come in different sizes for the various sized HVAC units. You will need to know the unit size of your compressor. This will ensure that the mounting brackets line correctly inside the condensing unit and that all of the copper tubing and connections are correct.
If you are in doubt of the size, look for the model identification late, which will tell you the name, make, and model numbers of the compressor. From there, you can search online for the specific model to get the needed specifications.
Consider Brand of Original Compressor
It is typical for homeowners replacing a compressor to look for the best deal. However, the unit you are replacing was most likely matched with the HVAC system you have for a reason. It is generally advised to replace the old compressor with an OEM replacement, or at a minimum, a model from the same manufacturer.
Before you start tearing out the old compressor, you should check the paperwork to see if a warranty covers the compressor. In most cases, if the warranty period is still active, you can save a lot of money by having a professional do the replacement by making a warranty claim.
You should note that labor warranties are often shorter than the warranty on parts. You may have to pay for the replacement labor out of pocket, but this will still save you time and potentially a lot of money by taking on the project yourself.
Age of AC Unit
Finally, it is worth considering the entire AC unit, its age, and its condition. With labor costs already established, it may be a wise move to replace the whole system. The blower motor, evaporator unit, and the condensing unit might cost you more to replace, but if they are going out within the next few years, it could be a wise investment to get it all done at once.
AC Compressor Warranty Guide
While the original warranty will vary by vendor, manufacturer, year of purchase, and even model number, we can give you a basic rundown of what to expect for a warranty length.
If you find a compressor with a warranty of fewer than five years, you really should find another compressor. Five years is the industry minimum for compressors and most condensing units for split AC systems. A well-known brand will make slightly more affordable compressors by offering older model internal parts. The warranty is usually the first thing to get cut, along with the price tag.
Goodman is a prime example of this. If you buy a new Goodman compressor, you automatically get a 5-year limited warranty without having to do anything. However, if you register your compressor and meet specific predefined requirements (having a newer or more efficient HVAC system, for example), the warranty is extended from an additional five years to a lifetime warranty.
Ten-year warranties are more accepted and are easily the average warranty period for an AC compressor in a stacked or split home AC system. Companies like Lennox, Goodman, Rheem, Trane, and many others offer a ten-year warranty on most of their compressor lines.
12 + years
If you find a warranty that exceeds 12 years, you know you have something good. You will have to pay a little extra for these compressors, but the long-term benefits may be worth it. American Standard and Rheem both offer warranties greater than a dozen years for certain models, sizes, and types of compressors.
Usually, to get a warranty for over ten years, you will need to purchase other participating products, such as the entire condensing unit, or a fan motor, along with the compressor itself.
While the large print will state a lifetime warranty, the smaller print will tell you it is only as long as you own the home.
Even smaller print might indicate that the warranty is only valid if certain criteria are met, such as installation by a certified and approved electrician.
When dealing with a lifetime warranty, make sure you read and understand all of the details and follow all instructions for registration and compliance. You should also keep a photocopy of the warranty, the purchase receipt and other documents in a safe and secure place.
In most cases, the compressor warranty will not cover labor. This means that while the cost of a new compressor, should yours burn out within the warranty period, is covered, removal and installation are not.
Rheem, Ruud, and Tempstar are known to cover labor as well as the compressor for a certain time frame. Make sure you read their requirements for qualification for your specific model before you pay, though.
You might have to pay a professional electrician to remove the old compressor and install the new one. However, this is a recommended practice anyway. When dealing with 220 volts and the chance of being fined up to $10,000 for releasing refrigerants into the atmosphere, a compressor replacement is something better left to the professionals.
AC Compressor Maintenance
When we speak of compressor maintenance, we mostly refer to the condensing unit you will find outside your home (if you have a split AC). Because the compressor is housed in the condensing unit, general maintenance need only apply. Here are things you can do to protect your compressor and prolong its functional life.
- Replace your AC filter regularly.
- Clean the louvers of the condenser, removing any debris, build-up, or contaminates.
- When the ambient temperature drops below 40 degrees Fahrenheit, wrap the condenser to prevent freezing.
- Keep the condenser unit free of obstruction, branches, bushes, etc. A minimum of two feet in the rear and four feet on the sides and front should be maintained. More if possible.
- If your compressor has a high-pressure switch, engage the switch during the summer months.
- Shield the compressor from direct sunlight to help maintain the temperature, when possible.
Signs of a Bad AC Compressor
How do you know if the AC Compressor is going bad? There are a few tell-tale signs that the compressor itself is on the way out.
Be warned that most of the following situations could also be another part of your HVAC unit (the air filter and thermostat are common problems that can simulate a bad compressor). Be sure to check everything before jumping to a compressor replacement.
AC Not As Cold/System Is Blowing Warm Air
If your AC kicks on as normal, but the air coming out of the vents is warm or not as cold as it should be, the compressor may be failing. This is also a sign of bad airflow. Before diagnosing the compressor, you should change the air filter and clean the condenser coils. It is also possible that you have too much or too little refrigerant in the system.
System Keeps Tripping Circuit Breaker
If the circuit breaker in your panel trips every time the compressor kicks on, this can be a sign of electrical overdraw, which means your compressor is on the way out. It is also possible this is due to an overheated unit, or one low on refrigerant (causing the compressor to overheat).
If the compressor itself is making loud noises all of a sudden or you hear strange sounds coming from the condenser unit and you have verified it isn’t the condenser fan or fan motor, the compressor could be worn out internally.
Compressor Clutch Not Moving
If your automotive AC isn’t working, you may find that the clutch doesn’t engage. This can be a sign that the compressor is bad. It is also possible that the bearings in the clutch plate have worn, or there is an electrical connection problem.
The Outside Unit Shakes When It Starts Up
If your condensing unit vibrates or shakes when the system kicks on, the compressor could be to blame. Double-check the compressor mounting bolts to ensure the rubber feet are intact and that the bolts haven’t rusted out. If not, the compressor is most likely faulty.
Common Causes of AC Compressor Failure
An AC compressor, at some point, will fail. With constant temperature extremes, moving parts, electrical connections, and refrigerant contaminants, it is only a matter of time. The most common causes of AC failure are overheating, freezing, and improper refrigerant levels.
Poor maintenance can lead to an early demise of the compressor. Proper airflow is needed, and cleaning the coils and louvers of the condenser regularly, is required. If the fan motor goes out, this can also lead to overheating.
A small leak in the refrigerant fill valve cores can lead to compressor failure by slowly leaking refrigerant. Similar to having a clogged air filter, the system will work twice as hard when the levels are low, or the filter is dirty.
Age is another factor. If your compressor is over ten years old, you should maintain regular annual inspections of the entire system.
AC Compressor Replacement & Repair Costs
So how much does it cost to replace your AC compressor? The answer depends on a lot of factors. Let us break it down for you here.
If your compressor is still under warranty, you should make a claim. However, you will also need to read the fine print of the warranty to find out exactly what is covered. As we mentioned before, labor costs generally aren’t covered by the warranty. Neither are extra replacement parts such as the filter dryer, copper tubing, or electrical wires.
Once you call in the claim on the warranty, the cost of the compressor itself should be covered in full or at least prorated. You will still need to cover the labor fees, which can range from $35 to $200 per hour. This also doesn’t include the extra parts. Be sure to get a few quotes from licensed repair companies before making your final decision.
No Longer Under Warranty
If your compressor is no longer under warranty, you are responsible for covering the cost of the entire project. This will include all the charges above, plus the cost of the new compressor. Once you have found your compressor, you can then get quotes on replacement costs.
It is also wise to ask the repair companies if they will supply the new compressor. Compare that added cost on their quote to the cost of buying the compressor yourself. Usually, there is a bit of a mark-up if the company provides the compressor. You can save a little bit of money by frugal shopping for your compressor online.
Size and Type of Compressor
According to Home Advisor, the cost to replace the home AC compressor will range from $1,350 to $2,300.
This wide range is due to the cost of the various types of compressors. You will need to find out what type, capacity, and size compressor you currently have and replace it with the same size, capacity, and type.
Unfortunately, a compressor isn’t a part of the HVAC system that you can upgrade to bigger or better.
Unless you replace the entire HVAC system, you will need to purchase a compressor that matches the currently installed one.
DIY vs Professional HVAC Technician
There are a lot of times when a DIY project will save you time, frustration, and money. However, repairing or replacing your home and automotive AC compressor isn’t generally one of them. Unless you know the HVAC system, high voltage, and refrigerant handling processes, you shouldn’t mess too much with the compressor or the condenser unit.
The refrigerant is under a lot of pressure, and even on the low-pressure line, there is enough to prevent you from sealing the valve core or replacing a line filter. It is also illegal to purchase refrigerant without a license, not to mention the specialized tools needed to check the refrigerant levels in the system itself.
A mechanic can use computers and machinery to diagnose your car’s AC system properly. Likewise, if your home AC or compressor is still under warranty, it is always better to make a warranty claim than to jump in and attempt repairs yourself. Home Advisor says that the average AC service (non-warranty) costs between $164 and $550 with an additional $35 to $200 per hour for labor.
No amount is worth risking your health, and improper knowledge of the HVAC system can lead to electrocution, cuts, injury, or worse. You can also be fined up to $10,000 for releasing refrigerant into the atmosphere. In general, it is always better to call a professional to handle your HVAC or automotive AC issues.
There are a few things you can do, though. Regular and routine maintenance, cleaning, and preventative measures can be taken. For example, replacing your AC filter is quick, inexpensive, and simple to do. For less than $30, you can prevent most AC issues. Keeping the condensing unit clean and free from debris, as we discussed above, is also something you can do every week to keep your system running efficiently and keep the repairman away.
How to Replace your AC Compressor
If you do decide to replace the AC compressor yourself, you will need some equipment and tools.
- Reciprocating saw to cut refrigerant lines.
- Socket and driver set.
- Oxy-Acetylene torch
- Bucket of water
- AC manifold gauge set
- Sandpaper or pipe sander tool
- Metal file
- Brazing rods
- Personal protective equipment (gloves, apron, goggles, etc.)
- Empty refrigerant collection tank
- New refrigerant
You will also need the new compressor, which should be the same size, capacity, and type as the one you are removing. Remember, compressors are specific to the HVAC system and aren’t a piece you can “upgrade” by changing to a bigger or different type. Copper line tubing, a tube bender, AC filter dryer, and electrical wire may also be needed.
The process is straightforward but can be difficult. Take your time and ensure each step is completed before moving on.
- Shut the AC breakers off in the breaker panel.
- Remove the power disconnect block on the outside of the home. If your block is fused, use a voltmeter to test the fuses.
- Remove the access panel on the condensing unit and use a screwdriver to short the Herm and Common terminals as well as the Fan and Common terminals on the capacitor.
- Remove the fan shroud and pull it out of the way.
- Connect your AC manifold set to the high and low-pressure line connections as well as to the empty refrigerant tank.
- Remove all of the refrigerant in the system.
- Close the refrigerant lines off by closing the stop valves.
- Disconnect the power plug from the compressor (usually a three-pronged rubber-coated, uni-directional plug on the top or side of the compressor).
- Cut the refrigerant lines at the compressor with the saw.
- Remove the mounting bolts at the base of the compressor and lift the compressor out of the condenser.
- Remove the rubber mounts around the bolt holes in the condensing unit (your new compressor should come with replacement rubber).
Before you can install the new compressor, you need to prepare the system. At this time, you should use the sandpaper to clean the refrigerant lines thoroughly. Use the file to sand down any burs or sharp edges and ensure the lines do not kink, bend or flatten at all.
It is advised to use a water hose to clean out the condensing unit at this time to remove debris and build-up from the inside of the unit that you usually don’t have access to. You can then replace the rubber mounting pads and begin the installation.
- Place the new compressor into the condensing unit in the same direction the old one was removed.
- Secure the compressor with the mounting bolts and place the refrigerant lines inside the ports on the new compressor. Note, the compressor will have flared tips for the old lines to fit into. This should be a snug fit. Be sure to sand the ports before sliding in the lines; there should be only bare, shiny copper on both ends.
- Wrap the compressor with wet rags where the ports meet the body. You should also wrap the refrigerant lines with wet cloths further down where they enter the condenser unit. This prevents heat transfer, which can ruin other parts of the system.
- Using the torch and brazing rods, braze the refrigerant lines back into the compressor. Ensure a complete seal all the way around.
- Locate the dryer filter on the high-pressure line and cut it off using the saw. Sand and clean the ends of the line and the ports of the new dryer.
- Wrap the dryer in wet rags to protect the filter material from excessive heat and braze the new filter dryer in place.
- Connect the electrical plug into the new compressor.
- Open the stop valves on the refrigerant lines. It is advised to replace the valve cores on the fill valves at this time.
- Connect the manifold gauge to the fill valves and the new refrigerant tank.
- Fill the system with refrigerant.
- Replace the fan shroud and secure it with the mounting screws.
- Reconnect the disconnect block and restore the breakers in the panel.
- Turn the AC on and test the lines for leaks. If a leak is found, you will need to start again to braze the lines until there are no leaks.
- After the system has run for at least 10 minutes, check the refrigerant levels. Fill as needed to ensure the proper level of refrigerant is in the system.
How to Save Money on AC Compressor Repairs
Saving money on an AC compressor replacement is difficult to do. Because of the tools needed, the knowledge required, and the time it takes to complete the job properly, there aren’t a lot of short cuts you can take.
You will be able to save some money by shopping around for the parts. If you purchase everything needed yourself and only pay the repair companies the cost of the labor, you may be able to save a few hundred dollars. However, going this route demands that you know exactly which parts to buy.
You can do the repairs and replacement yourself to save on labor costs. Even this route, though, comes with a downside. You must have a license to purchase refrigerant, and replacing the compressor will require new coolant.
If you cannot make this purchase, you will need to call in a professional. It is almost impossible to think you can find a repair company willing to purchase the refrigerant for you and let you do the work without them.
Safety Maintenance Tips
You should protect your eyes at all times. Safety goggles are a must. You should also protect your hands and forearms.
Refrigerant can instantly freeze your skin leading to frostbite. The acetylene torch can also burn your skin or worse.
When you remove the fan shroud, the top of the coils and the fan blades will be exposed and are very sharp. Caution needs to be taken when dealing with the cover and fan.
When brazing the copper lines, it is important to keep the cloths wet and the system around the area you are working on cool. It is also advised to have a spotter nearby with another bucket of water or a fire extinguisher to watch the space around you while you work.
Frequently Asked Questions
Let’s now answer some frequently asked questions about AC Compressors.
Where can I buy replacement AC compressors?
The best place to make a purchase is in-store. This way, you are ensured you are getting the correct model and type of compressor for your unit. Shopping online can also work, but it is better to go through the manufacturer’s website than through third-party sites like Amazon.
How long do AC compressors last?
HVAC systems are closed-systems, meaning they aren’t open to the elements and therefore last a bit longer. On average, though, a home AC compressor should last between 10 and 20 years in good repair. A car’s AC compressor can last anywhere from 5 to 20 years, depending on usage amount and maintenance.
Do home warranties cover AC compressor replacement and repairs?
Many home warranty companies do offer entire HVAC systems in their coverages. Others will have them as add-ons you can pay extra for. If the coverage for the HVAC system is there, it will include repair, replacement, and parts for the AC compressor.
The repair of a home air conditioner compressor is almost impossible. However, the replacement can be done by a repair technician or as a DIY project if you meet the requirements. You should expect to pay about $1,300, at least, for a replacement of the AC compressor.
This will include the labor and parts in most cases; however, you should get a minimum of three quotes from reputable repair companies before you pay anything. Make sure everything you need is included, so there aren’t any surprises. It is also wise to pay for an inspection before getting a quote for the replacements.
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