(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
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.
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.
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.
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
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
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
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
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.
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.