5 Symptoms of a Bad AC Compressor in a Car

(Updated on March 15, 2021)

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, also known as an AC compressor. What this component does is it creates pressure which pushes the refrigerant and keeps it flowing smoothly. It also heats up the refrigerant, which plays an important role in the production of cool cabin air.

As long as the AC compressor stays functional, you should have a stable flow of cool air coming from the vents. But like anything, an AC compressor can fail.

How an Air Conditioning System Works

A/C

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.

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. People who use their air conditioners on a regular basis will experience problems with them sooner than those who never run the AC.

There are some warning signs that will present themselves if your AC compressor is starting to go bad. Below are 4 common symptoms.

1) Strange Noises

serpentine belt squealing noise

If you switch on your air conditioner and there are a lot of strange noises being generated, then your AC compressor is likely starting to fail.

The compressor relies on a sealed bearing and numerous other components to turn. If the internal bearings or components were to get damaged or worn out, then it will make it more difficult for the compressor to operate properly.

Strange noises will only be the beginning of the problem. That is why you should take this symptom as an early indicator that you need to get your AC compressor replaced.

2) Hot Air From Vents

air conditioning vent

If you turn on your air conditioner and you only get hot air blowing out of the vents even after a couple minutes, this is a clear indicator that your AC compressor is failing.

If the refrigerant cannot circulate through the air conditioning system because of a bad compressor, then it is not going to create the cool air that you want. As a result, you will have hot air instead.

This might be a gradual process where you will first feel the cool air getting slightly warmer. After a while, the air will get to the point where it is completely hot with no coolness whatsoever.

3) Leaking Fluid

The AC compressor has its own internal bearings which prevent fluid from leaking while it is pressurizing the refrigerant. If these bearings become worn out or damaged then fluid can easily leak through them.

You will need to replace the bearings rather than repair them.

It’s crucial to take care of leaking refrigerant quickly, as the most common type (freon) is very harmful to the ozone layer of the atmosphere when it is released into the environment and evaporates.

4) Skipping or Squealing Belt

bad serpentine belt symptoms

This is a sound you may hear when trying to start the air conditioning system is the AC compressor is bad and the belt can’t properly turn with it.

5) Stuck AC Compressor Clutch

The AC compressor clutch allows the compressor to use the engine power only when it is needed.

If the clutch were to get stuck or seize entirely, then it would not be able to correctly transfer power from the engine over to the compressor. The AC could be stuck in the “on” position (eventually causing early wear damage to the air conditioning components) or it may be locked in the “off” position and not work at all.

You can check under the hood of the car while the engine is running to see if the compressor clutch is spinning when the AC is switched on (you may need to check the manual to see where the clutch is on your vehicle if you’re unsure).

In most cases, you won’t be able to repair the clutch either if it has seized like this. Your only option would be to replace the clutch and sometimes the entire compressor.

AC Compressor Replacement Cost

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car A/C compressor replacement cost

An AC compressor is a very significant component in any vehicle and thus will be one of the more expensive parts to replace when necessary.

First, make sure to check the belt which connects the AC compressor to the engine, because sometimes a worn or damaged belt can cause the same symptoms. If a faulty belt is not repaired in a timely manner then it will probably damage the AC compressor.

The component itself can cost anywhere from $650 to $950 or more. The labor costs will likely be anywhere from $150 to $200. This means that you could be looking at a total price of $800 to $1,150. There will also be taxes and fees added to these totals as well.

Conclusion

While the air conditioning system is not an entirely necessary system in the car, it’s very useful for defogging the interior windows (by absorbing excess moisture from the inside air) and of course, for cooling the interior off on hot days.

If you are unable to afford a replacement right now, just expect warm air to always be blowing through the vents into the cabin.

41 thoughts on “5 Symptoms of a Bad AC Compressor in a Car”

  1. 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.

    Reply
  2. 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?

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    • 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.

      Reply
      • 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.

  3. 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???

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    • 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.

      Reply
  4. 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

    Reply
    • 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.

      Reply
  5. 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?

    Reply
    • 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!

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      • 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.

  6. 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?

    Reply
  7. 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?

    Reply
  8. 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.

    Reply
    • 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.

      Reply
  9. 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?

    Reply
  10. 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?

    Reply
  11. 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?

    Reply
  12. 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?

    Reply
  13. 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:

    Reply
  14. 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.

    Reply
    • 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.

      Reply
  15. 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.

    Reply
  16. 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?

    Reply
  17. 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.

    Reply
  18. 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!

    Reply
    • 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.

      Reply
  19. 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????

    Reply
  20. 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.

    Reply

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