Overview of Car A.C. Compressor

The car ac compressor is majorly the heart of the air conditioning system. It is responsible for keeping the refrigerant flowing and thereby ensuring smooth performance. So, in case there is any problem with the compressor, the entire air conditioning system will also be affected. Most importantly, a bad ac compressor can prove to be dangerous. Usually, when a compressor begins to fail, it shows a few warning signs.

Air Conditioning System Operating Principle

Basically, the AC system works by 2 principles: evaporating liquids absorb heat, while condensation from vapor to liquid transmits heat to objects and their surroundings. 

The refrigerant is pumped from the compressor under high pressure and under high evaporation temperature. During this stage the refrigerant is pumped to the condenser or the hot rig in steam. At the condenser the temperature of the medium is very high, the fan blows the condenser, the vapor liquid is cooled, condensed into a liquid under high pressure and low temperature. 

The liquid refrigerant continues to circulate to the filter or desiccator, where the refrigerant is purified by absorbing all moisture and impurities. The expansion valve regulates the flow of liquid into the evaporator (evaporator). It lowers the pressure of the refrigerant. Due to the drop of pressure, the liquid becomes a vapor in the evaporator. 

AC system works by 2 principles, evaporating liqui
AC system works by 2 principles, evaporating liquids absorb heat, while condensation from vapor to liquid transmits heat to objects and their surroundings. Source: Drive2

During evaporation, the refrigerant absorbs heat in the car cabin. It means cooling the air mass in the cabin. The air taken from outside comes through the evaporator. Here, the air from the evaporator takes away a lot of energy through the radiator leaves, therefore the temperature of the air will be reduced very quickly. Meanwhile the moisture in the air will also condense and expose. At refrigeration platforms, when the liquid medium is at a high temperature, the pressure becomes a vapor liquid with a low temperature and pressure.

When this process takes place the refrigerant needs a lot of energy, so it takes energy from the air around the evaporator. The energy does not go away but converts from one form to another. The air loses energy, therefore the temperature drops, creating cold air. Refrigerant is in the vapor form, under high temperature and low pressure, returned to the compressor.

AC Compressor Working Principle

The compressor is housed within the condenser unit and the component that starts the chain reaction cools the refrigerant. It should be noted that heat moves toward cooler areas. When the room temperature air passes through the evaporator unit, heat is eliminated from the air. The heat from the air passes along to the refrigerant, which is then fed into the compressor.

AC compressor operating principle.
AC compressor operating principle.

The refrigerant is then compressed, which condenses into a fluid, and is then released under pressure. At this point, the refrigerant is much hotter than when it came in, but the heat is then dissipated through the condenser coils. By the time it reaches the end of the loop, the refrigerant is cold again and fed into the evaporator coils. This cycle continues as long as the air conditioner is turned on and the output becomes hot air instead of cold. 


Your AC compressor is making more noise than usual under the hood

Under the hood, there are many moving parts, many of which produce sounds and noises that you may or may not recognize. Because of this, and the unfamiliarity of many car owners with the noises and their causes under the hood, it can be hard to decipher which noises are unusual and which ones are completely normal. According to JD Power, abnormal, high-pitched squeal coming from under the hood could be caused by several components of an AC compressor failing, including the serpentine belt and other easy to repair parts or more complicated parts that will require an entire replacement.

What Are the Signs and Symptoms of a Bad A/C Compressor?

As we noted above, recognizing the signs when your air conditioner’s compressor might be in the early stages of breaking down or wearing out will keep your home cooler when you need it and likely result in a smaller repair bill. It’s crucial to know how to tell if your A/C compressor is bad.

1. A Lack of Hot Air Being Released OutsideSome of  are as follows.

1. A Lack of Hot Air Being Released Outside

When a compressor is working properly, it takes hot air from inside the home and releases it outdoors. A good way to tell if your compressor is starting to develop a problem is to hold your hand near the fan on the air conditioning unit. If that air is not hot but is instead lukewarm or cool, it’s a sign that your compressor could be having problems. It could mean the unit is not compressing the gas properly.

It might also be a sign of a refrigerant leak. If you’ve noticed that your system has been losing cooling power over time, a refrigerant leak could be the reason. A leak causes strain on the compressor.

2. Loud or Strange Noises From the Unit

Have someone in your home turn on the air conditioning while you stand outside beside the unit. If everything is working properly, the unit will start smoothly, and you’ll hear the compressor and the compressor’s fan motor working properly. If the unit, however, starts vibrating or makes a rumbling noise, a popping sound, banging noises, clicking, growling, clattering or screeching noises, it could be the sign of several potential problems.

Any of these noises might signify that the A/C compressor is having electrical problems. It could also mean that the compressor or a fan is loose thrashing around in the housing. If the unit vibrates when it starts, it may mean that the compressor is “hard starting,” or having problems starting — a telltale warning sign that the air conditioner compressor is about to fail. In any of these cases, you should immediately turn the air conditioning unit off and call an HVAC professional to make repairs.

3. Failure of the Compressor to Turn On

If you notice that the air conditioning is not cooling your home to the temperature you’ve set and the fan inside your home is working properly, check your condensing unit outside your home. If you hear the fan running but the aircon compressor is not running, you have a problem. The compressor should be clearly audible over the fan.

If this is the problem, you may face a replace or repair choice. Failed compressors can be expensive to replace so how to know if the A/C compressor is bad is vital. If your system is aging and has been in operation for about 10 or 15 years, it might make more sense to invest in a new air conditioning system rather than a costly repair.

What Happens If The Car’s AC Compressor Fails?

The condenser can’t do its duty of changing the gas into a liquid if the refrigerant gas isn’t compressed at the air conditioner compressor. You’ll notice that the air in the automobile isn’t as cool as it should be.

When a car’s air conditioning compressor malfunctions, debris can spread throughout the system, resulting in potentially costly repairs. Diagnosing and fixing an air-conditioning compressor problem early on can reduce the cost of getting your car’s air conditioning operating again.

Here are the ways to see if your car’s air conditioning compressor needs to be replaced:

Step 1: Turn The AC On High While The Engine Is Running

The air conditioner in the car will turn on as a result of this, and the compressor will turn on as well. Under low pressure, the car air conditioner compressor will suck refrigerant from the evaporator, compress it, and send it to the condenser under high temperature and pressure.

Step 2: Keep An Ear Out For Any Strange Noises

Unusual noises can occur for various reasons, so have a look at the list below of bad AC compressor symptoms before assuming you need a new car air conditioning compressor.

  • Look for any splits, cracks, or missing nuts or bolts in the clamps and fixing points.
  • Examine the hoses and lines to see if engine vibrations are being transferred to the cabin. Hold each line in one hand to see whether the odd noise goes away.
  • A belt drives the car’s air conditioner compressor. Unusual noises could be caused by worn belts, clamping devices, tensioner pulleys, or clutches.

If none of these are the source of the strange sounds, have the car inspected by an expert. Noise might be caused by high pressure in the system or contaminants of the air conditioner refrigerant.

Step 3: Check The Air Vents For Cool Air

If the vents aren’t blowing cool air, there are a few bad AC compressor symptoms you may have to rule out:

  • When the air conditioner is turned on, make sure the cooling fans are running.
  • Check to see if the cabin air filter is clogged.
  • Ensure that no leaves, bugs, or dirt have accumulated in the condenser, obstructing ventilation.

Step 4: Look Under The Car For A Visible Leak

If you have a leak or have ruled out the other possibilities, you’ll need to take your car to a qualified mechanic who will test the system and diagnose the issue.

Final Verdict:

The air conditioning compressor is one of the critical components of a vehicle’s air conditioning system. It is in charge of pressurizing the AC system and maintaining the refrigerant flowing to function properly. Because the air conditioner functions in a constant cycle of on and off, it is prone to wear every time it is turned on. It will ultimately fail and need to be replaced, just like every other component on a car.

Because the compressor is in charge of pressurizing and distributing the refrigerant, any problems with it will impact the remainder of the AC system. Car maintenance is critical, and many people overlook the need for car air conditioning. When you see bad AC compressor symptoms, it’s recommended to assess and fix it.

Troubleshooting Air Compressor Issues

That said, you can troubleshoot before a visit froIn the case of most of the problems we mentioned above, the best thing to do is to call an HVAC professional and have them come look at your unit. They’ll be able to diagnose the problem and make the needed repairs. Air compressor issues are not easily solved by DIYers. In fact, if you’re not careful, you could hurt yourself or make the problem worse.

That said, you can troubleshoot before a visit from an HVAC expert to determine whether the air conditioning compressor is failing. Here’s how.

1. Play With the Thermostat

Turn your thermostat as low as it will go. Doing so should start the air conditioner. If it doesn’t, it signals that you have a problem, which may be the compressor. If the unit starts but makes some of those strange or loud noises mentioned above, it signals another potential problem. If the fan is running but you don’t hear the compressor running, that could be something else entirely.

2. Investigate Your Circuit Box

If you’re having a hard time getting your A/C to start, it may not be a compressor problem. You should always check the circuit breaker to make sure it hasn’t accidentally tripped. This situation may be the case if you have too many appliances going at the same time — the vacuum cleaner, the oven, the television and the air conditioner, for instance.

Most circuit breakers can be found in the basement, the kitchen or perhaps in a hallway or a garage. When you open it, you should see labels beside each circuit that tells you which appliance it powers. A circuit breaker switch has three positions — on, off, or in between. If the circuit breaker is in the middle, switch it off before you turn it back on. If your air conditioning starts up with no problems, you’re okay, but if it keeps happening, it’s time to call an HVAC professional.

3. Check the Fuses

The problem could be a blown fuse. Normally you find the fuse box on a wall on the outside of your home. If you want to check to see if the fuse is the reason the air conditioning isn’t operating normally, make sure you cut the power supply to the unit — in most cases at the circuit breaker — and take out the fuse.

You’ll need to use a multimeter, which you can pick up at any local hardware store. You can then perform a continuity test with the multimeter. If the multimeter says you have blown the fuse, you just need to replace the fuse.

If the circuit breakers and the fuses are all operating properly, you’ll know a faulty compressor is probably the cause of your air conditioning problems.

4. Look for Blockages

If you’ve tried all the above measures, check the compressor’s condensing coil and fans to make sure there are no blockages or obstructions. Branches or even too many leaves can create blockages that undermine the air conditioning compressor’s ability to do its job.

AC Compressor Replacement Cost

The average AC compressor replacement cost is between $400 and $1200, depending on the car model and labor cost. An AC Compressor costs $200 to $700 while labor costs $200 to $500.

The AC compressor itself is quite a complex part, and therefore it can cost a lot to buy a new one.

The labor costs are often around $100 for just the AC compressor replacement, depending on the car model.

However, after the AC compressor replacement, the AC system needs to be refilled, and this procedure usually costs $100 to $200. Before refilling the AC system, you also need to do a leak test on the system, which can take a long time and, therefore, the labor costs a lot.

Learn more: How Much Does an AC Recharge Cost?

The cost to replace your A/C compressor will vary greatly depending on how accessible it is to change, what refrigerant your vehicle uses as well as what type of compressor is fitted. 


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