Every air conditioning system of a vehicle depends on a steady flow of refrigerant to circulate through it. This refrigerant is what allows the air conditioner to produce the cool air which comes out of the vents in the dashboard.
The only way this refrigerant can continue flowing properly is from a component called an air conditioner compressor (aka: AC compressor). What this component does is it creates pressure which pushes the refrigerant and keeps it flowing consistently.
But like anything, an AC compressor can fail. Here are some common symptoms of AC compressor failure and how much you can expect it to cost to fix it.
Bad Car AC Compressor Symptoms
AC compressors endure a lot of stress. Car air conditioning systems get turned on and off constantly and this power fluctuation may put a lot of wear on the compressor.
Over a certain number of years, this stress could wear down the compressor and cause it to eventually malfunction. Let’s look at the most common warning signs that may present themselves with a bad AC compressor.
1) Warm Air From Vents
If you turn on your air conditioner and warm air blows out of the vents, even after a few minutes, your AC compressor might be failing. Without a working compressor, refrigerant can’t circulate properly, preventing the system from creating cool air.
You may notice this gradually. At first, the air might simply feel less cool, but then becomes increasingly warmer over time. Eventually, you’ll get no cool air at all, just warm air from the vents.
2) Strange Noises
When you turn on your air conditioner, listen for unusual sounds. A failing AC compressor often produces strange noises. These could be grinding, squealing, or rattling sounds coming from the front of the engine bay.
The compressor has several internal components, including bearings, that can wear out over time. As these parts degrade, they make it harder for the compressor to operate as intended, resulting in these noises. If you hear these sounds, take it as an early warning sign that your compressor needs attention.
3) Reduced Cooling Efficiency
Your AC system may still produce cool air, but nowhere near as effectively as before. In many cases, you’ll start to notice that it takes longer for your car’s interior to cool down or that it doesn’t get as cold as it used to.
While the AC compressor isn’t the only possible cause, this could indicate that the compressor is starting to fail but hasn’t completely stopped working. The compressor might be struggling to circulate the refrigerant, resulting in less efficient cooling.
4) Moisture or Water Inside the Car
If you notice excessive moisture or water droplets inside your car, especially on the dashboard or floor near the front passenger footwell, it could indicate an AC compressor issue.
While some condensation isn’t all that abnormal, too much moisture suggests a problem. A failing compressor may not effectively remove humidity from the air, leading to excess moisture in the cabin. This can cause foggy windows, musty odors, or even water pooling on the floor.
5) Leaking Refrigerant
The AC compressor has internal seals that prevent refrigerant (freon) from escaping while it’s under pressure. If these seals wear out or deteriorate, refrigerant can leak. You might notice a thin, oily substance under your car or a slight hissing sound when the AC is on.
Refrigerant leaks are serious, as they reduce your AC’s efficiency and can harm the environment. Think you have a refrigerant leak? Get it checked by a professional as soon as possible.
6) Skipping or Squealing Belt
When you start your AC, pay attention to any squealing or skipping sounds from the engine area. These noises often indicate a problem with the belt that connects the AC compressor to the engine.
If the compressor is failing, it may not turn smoothly, causing the belt to slip or squeal. This sound is usually most noticeable when you first turn on the AC.
7) Inconsistent AC Performance
Your AC might work fine one moment and then suddenly stop cooling effectively the next. This on-and-off performance could indicate that the compressor is failing intermittently. You might notice that the cool air comes and goes, or that the AC works well on some days but not others.
This inconsistency often suggests that the compressor is on the verge of complete failure. Unfortunately, this random symptom is often hard to replicate by a professional mechanic but if you’re aware that it’s going on, it can help them in the diagnostics process.
AC Compressor Replacement Cost
We recommend Parts Geek for the best prices and selection.
The truth is, replacing a vehicle’s AC compressor isn’t cheap. On average, expect to pay $1,000 to $2,000 for professional replacement. Here’s how it breaks down:
- Parts Cost: A new, good quality AC compressor typically costs between $400 to $1,000 depending on your vehicle’s make and model. High-end or luxury vehicles may have even higher part costs. While you may be able to find 3rd party compressors compatible with your vehicle for $150 to $200, the quality can be hit or miss and many mechanics won’t install them for you or warranty the job.
- Labor Cost: Because the complete replacement procedure usually takes anywhere from 4 to 8 billable hours, a large chunk of your final bill will be labor. Expect anywhere from $300 to $1,000 on labor costs, with the hourly rate mainly determined by type of shop and location.
- Additional Expenses: It is often recommended to replace the AC condenser and expansion valve at the same time. In fact, some manufacturers require it for the warranty to be in effect. Because of that, your final total might be $100 to $400 higher.
Before committing to a full replacement, have your entire AC system inspected. Sometimes, issues that seem like compressor failure can be caused by simpler, less expensive problems like a worn belt or low refrigerant levels.
As with any expensive service, get multiple quotes from reputable shops. Sure, it may be a small hassle, but the few extra minutes spent can often save you hundreds of dollars.
If you’re comfortable with auto repairs, you can save a good amount of money by replacing the compressor yourself. However, it’s no simple task and proper handling of refrigerant requires special equipment and knowledge. With AC compressor replacement, a large majority of car owners prefer to leave this job to the pros.
Common Causes AC Compressor Failure
Air conditioner compressors can stop working for several reasons. Here are some of the most common:
- Lack of Lubrication: Like other mechanical components in an engine bay, a compressor has many moving parts that need proper lubrication to work well. When there’s not enough oil in the system, the compressor can overheat and seize up.
- Dirty Coils: The condenser and evaporator coils can get clogged with dirt and debris over time. This makes the compressor work harder than it should, which can lead to premature failure.
- Refrigerant Leaks: If there’s a leak in the AC system, the refrigerant level will drop. This makes the compressor run constantly to try to maintain the right pressure. Running non-stop can cause the compressor to wear out faster and even overheat.
- Electrical Problems: The AC compressor relies on electrical signals to work as it should. Issues with the AC clutch, relay, or switches can prevent the compressor from turning on or off as intended from the factory.
- Age and Wear: Similar to almost anything, AC compressors wear down over time. The more you use your air conditioning, the faster the compressor will wear out. It is said that most compressors last between 8-12 years with regular use. Even if you live in a cooler climate, your AC is typically on when blowing warm air to defrost windows since it acts a dehumidifier.
How an Air Conditioning System Works
The air conditioning system of a vehicle works much like a refrigerator. The AC compressor is driven by the engine of the vehicle, connected by a belt on the front of the crankshaft. It’s the driving force behind the cycle of hot and cold refrigerant movement.
The compressor pulley is attached to the crankshaft so it always spins when the engine running. Since most people don’t want the AC on all the time, a compressor clutch connects the pulley to the compressor driving shaft when the AC is switched to “on” to make the compressor run.
Compressor
The compressor pressurizes (which also heats up) the gaseous refrigerant that it receives from the evaporator. It then sends the hot gas to the condenser.
Condenser
The condenser itself becomes hot as the hot refrigerant passes through it, and this heat is then transferred to the cool air being forced into it as the car drives along. The evaporation valve at the end of the condenser cools the refrigerant vapor even more so that it turns back into a liquid.
Evaporator
The cool liquid refrigerant enters the evaporator, where warm air is blown over it by a fan. The evaporator is under low pressure, so the boiling point is much lower. The liquid refrigerant absorbs the heat from the air so that it boils, evaporates, and becomes a relatively cool gas.
The warm air that was blown over the refrigerant is now cool air which is blown into the cabin to cool everyone inside.
- Sun Visor Won’t Stay Up? (4 Common Causes and How to Fix) - March 20, 2025
- 8 Symptoms of Low Engine Compression (and What It Means) - March 13, 2025
- 7 Common Adaptive Cruise Control Problems (and What Causes Them) - March 6, 2025
My 1999 toyota Sienna is my wonder car. Runs like a champ even with 195,000+ miles. On my way home from road trip and within 10 miles from home, my air conditioner went quiet and noticed although the button was pushed in, the light wasn’t on. I turned the air flow to off and turned off air conditioner and tried to turn it both back on. AIr flow came out normal and air conditioner light still didn’t turn on. It was a long drive day and just wanted to get home, so I didn’t try again.
In the old days having A/C (Air Conditioning System) in a vehicle was considered a luxury. But in the modern era, it is a basic facility that every auto manufacture gives with their vehicle to customers. The condenser in the air conditioner is a very vital component in the process of air-drying and air-cooling. If something bad happens to the condenser of the air conditioner then it will not work effectively, especially in the summer season.
I have a 2004 Honda Accord. I was told the AC Compressor Unit needs replaced. No AC only hot air. My radio seems to over heat and shut off the clock even disappears. Then when the clock comes on I can turn it back on. But it shuts off again shortly after. Is this due to the bad AC Compressor Unit????
I don’t know. It sounds like the radio might not be grounded properly.
I am newly widowed and when it rains it pours. My 2013 BUICK VERANO is on, it only blows warm air. The condenser was replaced 4 months ago due to a front end collision. We hoped that would fix it. The Freon shows at 100%. There are no noises. I had a check at Auto Zone but nothing popped up about air. (My car is also stalling every time I stop at red lights or anywhere else I have to stop for a minute). For this, I have been putting car in Neutral and revving to 20RPMS or so to keep it going, then when light tuens green, I shift back into D and it USUALLY works. With me being a female in late 40’s I know nothing about cars and am afraid of being taken. I don’t have the $ for that. Just spent $12k for husbands funeral. He was to have the car worked on last week, but of course that didn’t happen when he had his heart attack. ANY SUGGESTIONS OR HELP, MUCH APPRECIATED!
Hey Gina, I am sorry to hear about your husband. It could be the A/C compressor, I am not sure. I’m also not sure if the stalling is related to the issue with the air conditioning, or if there is a separate problem with a component such as the idle air control valve. You will probably need a bit of diagnostic work to know for sure. Good luck and I wish you the best.
Good day, I use a Toyota Matrix 2003 model. Whenever I put on my A/C and try to accelerate rapidly the car experience a seizure but it works fine when the A/C is turned off..please is this as a result of bad A/C compressor.
My engine runs hot with AC on and cools as soon as AC is shut off.
Have you verified the operation of both your radiator fans?
Good day, I use a Toyota Camry 2004. Whenever I put on my ac and I’m on speed my ac works perfectly well, but as soon as I stop in traffic, it blows hot air. Also when I have it in park, it blows well. It only stops when I’m in traffic. Please what do you suggest?
Do A/C compressors get tired?
I had a guy tell me it was pressurizing only at high rpm, and wanted to replace the compressor. I thought they either worked or not.
I have a 2010 Nissan Rogue I replaced the fan motor sensor and the fan motor now when I turn on the ac it blows hot air but sometimes it blows cold air.
Hmm, I’m not really sure about this. I’d start by checking the car for codes and taking it to e mechanic if nothing helpful comes up in the scan.
I have a 2012 Kia optima Turbo, I am now putting on my 5th compressor. Three from the dealership and two (Including this one) from a private shop. I have replaced condenser, compressor, something sort of valve(Forgot what its call) All four has a life span of 7-8 weeks: It works perfect then bam it just stops: Could it be an electrical surge:
Hi, my car makes a squealing type sound whenever the ac is on and I press the accelerator only while driving, it stops making any noises as soon as I turn the ac off. What could this be please?
Check the belt tension on the serpentine belt. The belt may be loose.
I have a 98 Chevy Silverado that blows cold air for maybe 5-10 seconds when turned on and then it sounds like something blocks the cold air or stops the cold air and it just blows hot air. It will continue to blow but just not cold. Any idea?
What is the usefulness of condenser and dryer in the system
The condenser cools the refrigerant and turns it from a gas back into a liquid.
hello my 08 focus’s condenser doesn’t spin when i turn on the a/c and it just blows out warm air. It’s full of freon, is my condenser bad?
Hi, I recharged the AC gas because my car was blowing hot air. This didn’t solve the problem so I had a garage take a look. I was told this was due to a faulty evaporator temperature sensor which is sending a signal telling the car that is it already cold and start to produce warm air as not to freeze over. I took it to another mechanic and was told it is a faulty compressor. I don’t know which one to believe as I don’t want to get one thing fixed for it to still not be working. Please help?
Did either mechanic test the system? I would believe the one who ran tests. If neither did, find a shop who will test so you know for sure.
Very good information. My husband turns on both heat and ac at the same time. Is this good or bad. I just replace the ac compressor on my CRV.
Nothing wrong with doing that, it’ll just give you warm, dry air. That’s what I’ve done in the winter for years. It’s often humid where I live and I’ll fog up the windshield if I don’t.
Hello,
2011 Nissan Murano in Phoenix AZ, can hear bearings like marbles in a metal box grinding around, air goes from cold to hot and back have to turn on and off to make it start and run cold air, have heard sounds similar to a cow mooing, dealership says pressure was overcharged with Freon & needed reset. Question is aren’t the bearings going out? Surely we need a new AC compressor right?
I have Toyota Sienna 2005. About 2 years ago, when I turned on the A/C on highway, it kept on blowing hot air. After trying on and off few times suddenly it started working and has been working fine since then. The vehicle has not run for last two months and today when I turned on the a/c it won’t blow cold air. I kept on trying(on and off) but it did not work.
At standstill,I can hear the clicking noise when a/c is turned on and engine ramping up.
Is it the problem with the clutch?
Not sure. It probably needs a recharge at the very least. While it’s in the shop they can check the compressor too.
Mine is doing same thing. Did you find a fix?
My AC starts blowing hot air when i start driving it takes a few miles before it starts blowing cool air but if i stop say in traffic for any length of time or am parked it will start blowing hot again until i get moving again. I am going to assume this is a sign my compressor has failed?
You maybe low on engine coolant, may want to check the anti-freeze level! Our old van used to do that when it was low!
You might also check that the condenser fan is coming on when the engine gets to operating temperature. If it doesn’t come on check for 12vdc at the fan plug. If you have voltage and the fan isn’t coming on then your fan motor is bad. The condenser fan must operate for your ac to blow cold air, especially when the vehicle is not moving.
What was the problem?
hi my toyota corolla 15 no noise just not blowing cold air. is this a compressor or just need freon??
It may have a leak, or simply need a recharge.
Hi there my 2010 Tahoe does put out cold air but when I turn on the air conditioner for the first time there’s a definite clunk coming from the area where the AC is. Could this be the compressor? It only does it when I first turn it on. Thank you thank you
It’s probably the compressor clutch. The clutch allows the serpentine belt to turn the A/C pulley without spinning the compressor until you want to turn the A/C on. At that point, the clutch engages and spins the compressor.
It may simply need an adjustment but a slight vibration as the compressor kicks in is fairly normal. If it’s more than a slight vibration, I’d take it to a shop just to have them make sure nothing’s wrong.
My a/c in my 2016 Nissan Altima went from blowing cold air to cool air and then hot air, what do I do about that???
The A/C system may have a leak, the compressor could be struggling, or you may simply need a recharge. I’d take it to a shop to have it looked at.
How would you fix that? There’s a lot of noise coming from the engine and I’ve been told it’s the AC compressor failing. How can I save it?
If it’s not simply the accessory belt slipping, you may have to replace the A/C compressor. A slipping belt usually makes a squealing noise, especially on startup or hard acceleration.
No leaks anywhere in my truck ac compressor runs no voices I charge it last couple days holds pressure but then all the refrigerant is gone. I was told I have a whole in the compressor but nothing leaking around the compressor when we che k it idk what to do!! We have put dye in the lines etc.
Wish I would have seen this sooner! All the warning signs were there. Now I have no choice but to replace the compressor when I could have taken steps to save it.