7 Reasons Why Your Car AC Is Not Working And How To Fix It

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Having a non-working AC in the middle of the summer can be pretty frustrating, but also expensive. Here are some pointers that can help you identify why your car AC is not working, and how you can fix them:

  1. AC Leaking Refrigerant
  2. AC Condenser Broken
  3. Electrical Issues
  4. Faulty AC Cooling Fans
  5. Faulty AC Accumulator Filter Drier
  6. Faulty Car AC Compressor
  7. Faulty AC Evaporator

How Does The AC Work

In order to understand your car AC system, you have to start at the refrigerant. The refrigerant is a chemical used in the AC system. When it is in a gas state, it is able to collect, absorb and hold heat. When it is converted into a liquid state, it releases that heat and that process repeats over and over again. That is how the AC works. In order for this process to happen, the pressure has to be right and all the components have to work properly. There are 5 major AC system components:

  1. Compressor and clutch
  2. Condenser
  3. Expansion valve
  4. Evaporator
  5. Accumulator filter drier

All of the components are connected by hoses.

A compressor pumps the refrigerant under pressure throughout the AC system. After leaving the compressor, the refrigerator enters the condenser before it is transferred to the cabin. The expansion valve transfers the refrigerant into a cold gas. From there, the cold gas passes through an evaporator and absorbs the heat from inside the vehicle. At the same time, a fan blows across the fins of the evaporator chilling the air that goes into the passenger cabin. The refrigerant then passes through a drier to filter out any moisture before returning to the compressor to begin the process again.

Now that we got that out of the way, here are the most common reasons why your car AC is not working:

Your AC Is Leaking Refrigerant

It’s actually very easy to find if your AC is leaking refrigerant.

  1. Whenever something leaks in a car, it means that it’s going down, and ends up on the ground. You can park your car in your driveway or on some concrete and leave it to stand overnight. In the morning, back up the car a little bit and see if there is fluid on the ground. If there is, you can perform a small test like smelling the fluid. If it smells like oil, then it’s oil. If not, if it has that freon/refrigerant smell, you got yourself a leaky AC.
  2. If you don’t want to wait 24 hours and you want to diagnose and fix your AC right away, you can perform another test. You can add a special dye to the AC system. But the dye is very difficult to see, so you will need a UV light. Start your car and your AC. Add the dye to the AC system. Grab your UV light and carefully light all the pipes that go in/out the AC system. It’s best if your car is parked in a garage and the light is off. If you are able to find where the leaking is coming from, mark that place and go to the mechanic. Or, if the area is very small, you can try taping it with a heat resistant tape.

Cost Of Repair

This may cost you anywhere from $150-$800. To have a technician inspect your AC, check all the hoses and connections will cost $100-$300. Recharging your AC can cost around $160. Changing some parts on your AC has an average cost of $488. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

In the best scenario, you can use a commercial product to stop the leaking. These products say that they will fix leaks in condensers, evaporators, hoses, and gaskets. The products go for around $25. If this doesn’t work, take your car to the mechanic.

The AC Condenser Is Blocked/Broken

This is a very common issue, and the symptoms are pretty clear. The mission of the AC condenser is very important and can be found on all car AC systems. The condenser is converting the refrigerant coming from the compressor. The refrigerant comes with a high temperature and high pressure and then it’s being converted into a high-pressure liquid and cooled thanks to the condenser.

  1. If your car AC is working, but it’s not cooling as it used to, you might be looking at a blocked/damaged condenser. If the air cannot flow freely, the cabin cannot be cooled properly.
  2. A blocked/broken condenser can cause a leak. Every part has a lifespan, and so does the condenser. When a condenser leaks, it is a noticeable leak and you have to replace the whole condenser because it is a one-piece part.

Cost Of Repair

You won’t be happy when I tell you what is the average cost to replace the condenser. The labor can cost anywhere from $160-$300. The condenser itself is from $240-$350. So, you are looking at an average cost of $500. It’s not that cheap, but, I cannot imagine a summer without an AC. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

This fix will require some tools that not everyone has at our homes.

  1. First, start off by recovering the refrigerant. For this, you need a machine. They cost anywhere from $300-$600. It will be cheaper if you just leak the refrigerator.
  2. Remove all parts(radiator, condenser fans, grills, headlights) that are in the way of the condenser.
  3. Remove the AC lines that lead to the condenser.
  4. Disconnect the condenser. Loosen up the bolts that hold the condenser. Remove it slowly and make sure you don’t damage the wiring.
  5. Install the new condenser.
  6. Reinstall the lines leading to the condenser.
  7. Recharge the AC with refrigerant.

AC Electrical Issues

These electrical issues are not as common as a refrigerant leak, but they still happen. Performing a visual inspection is a great start.

  1. The car AC has many switches and relays, and many parts mean more chances to broke down. Non-operating AC does not mean that the AC itself is broken, or a condenser or a fan. It can be the little things. There are a low-pressure and high-pressure cut off switch, power steering switch and wide open throttle switch. These components mission is to disengage the compressor while it loads. If your car AC turns on and starts to blow hot air, it could be because of the components that I mentioned above.
  2. Another thing that fails, and is an electrically operated component is the compressor clutch. This is a separate part from the compressor and can be serviced separately. This component is energized by a coil which pulls the clutch into a grip. This component connects the engine revolutions and a freon pump. This component can be checked and diagnosed with an ohmmeter. Replacing the compressor clutch can be a delicate operation.

Cost Of Repair

  • The low-pressure and high-pressure cut off switch costs around $15-$30.
  • The power steering switch costs around $25-$30.
  • And the wide open throttle switch costs $13-$20.
  • The compressor clutch is a little it expensive. It costs anywhere from $150-$300.
  • The labor costs $80-$200.

Repair It Yourself

I personally do not try to fix any electrical issues on a vehicle. If you don’t know what you are doing, it is best if you pay a mechanic. A small error with the electronics can lead to a damage. Anything from a blown fuse to setting your car on fire can happen.

Faulty AC Cooling Fans

As I said before, the condenser converts the refrigerant to liquid form. This means that the condenser has a lot of work and gets hot. This is where the AC cooling fan comes in to play. This component is designed to keep the condenser cool. Here are few symptoms that a faulty ac cooling fan has:

  1. If you feel a lukewarm air coming out of the air vents, that is the first symptom of a faulty ac cooling fan. This happens when the fan is not working and the condenser has gotten very hot.
  2. If your car overheats while idling can also be a symptom of faulty cooling fans. During the converting process, the condenser can create a big amount of hot air. This hot air gets to the engine and affects its temperature. This issue occurs only when your car is parked. Once you get the car moving, it will cool down from the airflow.
  3. Another symptom is a burning smell coming out of the AC vents when your turn on the AC. This happens when the condenser overheats to a burning point and emits an odor. The more you drive your car with an overheated compressor, the more damage is done. So, whenever you feel a burning smell, turn off the AC and fix your issue.

Cost Of Repair

The cost of a Fan can vary from $307-$784. Fans of BMW are the most expensive on the market. The other cars use fans with a price of $307-$440.

The labor cost is anywhere from $70-$238. Again, the BMW replacement is the most expensive. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

  1. Start the car engine and open the hood. Locate the condenser fan.
  2. Test the condenser fan relay which is located in the relay box under the hood.
  3. Check the pressure of the AC system. There is a general reading located in the manual of each car.
  4. Remove the condenser by removing the electrical connections and then remove the mounting bolts.
  5. Install the new condenser.
  6. Test the AC to make sure it is working properly.

Faulty AC Accumulator Filter Drier

This component acts as a filter for the car AC system. It is filled with a moisture absorbing material. It is filtering the debris that may get inside the AC system and it absorbs the moisture that gets pumped into the AC system. If this component fails, you are looking at a corrosion or leaks. A faulty ac accumulator filter drier can be diagnosed with these symptoms:

  1. If you hear a rattling noise when you turn your AC on could be because of the accumulator. The accumulator has chambers inside, and that noise could be because of internal damage(corrosion).
  2. If your ac is leaking refrigerant it could be because of the accumulator. If you notice a huge pool of refrigerant in the morning, you must act fast or all of your refrigerants will leak out.
  3. The moldy smell. I hate this symptom. This actually happened to me when I was on vacation and I couldn’t change the accumulator right away because I was in a different country. I will never forget that moldy smell.

Cost Of Repair

The Ac accumulator has a price range of $41-$103. The labor cost goes from $70-$126. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

This is also a complicated process.

  1. Store the refrigerant by using a recovery machine.
  2. Remove the evaporator tube nut.
  3. Disconnect all electrical connections from the AC.
  4. Remove the compressor hose, accumulator, retaining bracket bolt.
  5. Remove the O-ring seals.
  6. Lubricate and install new O-rings.
  7. Install the compressor hose, accumulator and retaining bracket bolt.
  8. Connect the electrical connections to the AC.
  9. Recharge the AC system.
  10. Test the AC.

Faulty Car AC Compressor

This is a component that you don’t want to fail. Not only will it disable your AC, but it will bring you a huge invoice to pay. This is the most important component of a car AC system. When it starts to fail, it will show a couple of warning signs:

  1. When you turn on the AC, you will not get cold air blowing. In a matter of a fact, it will be as same as you never turned the AC on.
  2. Very loud noises coming from the compressor. All kinds of noises can be produced from the internal bearings or seize. These small components are not something that you can replace. You will have to replace the entire compressor.
  3. When the clutch is not moving. This part is what turns on and off the compressor. If this component fails, it can leave the compressor turned on for a longer period of time, and again, you will have to replace the entire compressor.

Cost Of Repair

Like I said before, this is not something that you want to fix. It is very expensive.

The compressor can cost from $509-$3188. The labor is anywhere from $322-$805. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

  1. Check the pressure.
  2. Check the power and ground of the compressor.
  3. If found faulty, remove all the refrigerant using a machine.
  4. Remove the compressor, receiver drier, orifice tube and expansion valve.
  5. Install the new compressor and the remaining parts(receiver drier, orifice tube).
  6. Recharge the AC system.
  7. Test it.

Faulty AC Evaporator

This part regulates the AC temperature. Any damages to this component may disrupt the cooling process. This component usually starts to leak refrigerant when it gets damaged. The most common reason why it gets damaged is by debris that gets through the air intake.

  1. If there is no cold air coming out of the AC, it could be because of the evaporator. If the evaporator switch fails, it can affect the AC system.
  2. If the temperature changes from cold to hot. This can happen if the evaporator sensor sends an incorrect signal to the computer.
  3. Faulty evaporator could lead to the AC compressor not turning on. The evaporator temp sensor has an important role. A simple malfunction with the evaporator can disrupt the overall performance of the AC.

Cost Of Repair

Compared to the other parts, I can say that this part is inexpensive.

The evaporator costs anywhere from $144-$164. The labor cost is $126-$168. You can save up some money by fixing it yourself. Make sure you have the required tools before starting your work.

Repair It Yourself

  1. Store the refrigerant with a recovery machine.
  2. Cut the joint caps and disconnect the receiver lines.
  3. Tape the lines to avoid debris from entering.
  4. Clean the joints and all areas.
  5. Remove the blower unit.
  6. Disconnect the evaporator temperature sensor.
  7. Pull out the evaporator.
  8. Install the new evaporator.
  9. Connect all the lines.
  10. Test the AC.

Before you start working on your AC, make sure you have the required knowledge and tools to perform the task to the end. Do not start and realize in the middle of the repair that you are missing some of the essential tools. Make sure that you are very careful when working on the AC. As I said before, there are some parts that are very expensive. You do not want to risk damaging the AC compressor. If you have basic knowledge of cars, you can at least diagnose the issue and then go to the mechanic. This way your mechanic won’t lie to you and perform tests that are necessary but costly.

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