Why is My Car Air Conditioner Not Blowing Cold Air?

This is a common problem that happens nearly in every car with an AC. The air conditioner may stop working or blowing hot air even after making the right AC settings. It may not be easy to diagnose this problem due to the complexity of the air conditioning system in the vehicle. It becomes even more challenging to deal with the issue since it could also involve other components of the vehicle.

In this article, we are going to dive deep into the air condition components and know how they work. We shall also learn how to diagnose the faults of the air conditioner and how to fix car ac not blowing cold air. Therefore, by the time you read this article to the end, you will have an answer to the question “Why is my car air conditioner not blowing cold air?”

how to fix car ac not blowing cold air

How Car Air Conditioning Works

Let us start by having a good view of how the air condition system works, the function of each part, and how it affects the system. It is crucial to understand how all these parts work together to enjoy the cold air in your cabin. The major parts of the air condition system are:

Refrigerant: While this is not part of the system, it cannot work without it. The refrigerant is the lifeline of the air conditioning system. All the components of the system need it for the AC process to be a success. Refrigerant is found in a gaseous state. In high temperatures and pressure, the refrigerant is in a liquid state. There are many types of refrigerant codded like “R-134A”, “R-410A”, “R-22” and many others. You are therefore advised to stick to the recommended type for your vehicle. Check Here

Compressor: This is considered the heart of the air condition system. The job of the compressor is to compress the refrigerant and convert it from a gaseous state to a liquid state with high pressure and high temperature. For the compressor to work, it connects to the engine with a drive belt and takes its rotation from the engine.

Condenser: This is one of the most sensitive parts of the air condition system. The condenser is located at the front of the car. It looks like the radiator, but it is located right in front of it facing the cooling fans. The primary purpose of the condenser is to condense the high temperature and high-pressure refrigerant coming from the compressor. This happens when the refrigerant flows inside the tubes of the condenser while facing the cold air blowing from the front of the car.

Evaporator: This is the only component that is located inside the cabin. The rest of the components are located in the engine bay. The evaporator looks like a small radiator with the same fins and tubes. The main job of this part is to receive the cold refrigerant from the drier /receiver. As the air from the cabin blows through the cold evaporator core, it exchanges heat with the air from outside. That is when cold air is blown from air vents in the cabin.

Receiver: The receiver is used at the preparation stage. It removes any moisture in the refrigerant that it could have got while in the evaporator. The importance of removing the moisture is to prevent it from building up ice which may lead to blockage and damage of components.

Expansion Valve: The primary use of this part is to convert a high-pressure liquid refrigerant to a low-pressure liquid.

how to fix car ac not blowing cold air

The AC Cooling Process:

  • The process starts with the compressor compressing the refrigerant and converting it from gas to a liquid state. This increases the pressure and temperature of the refrigerant.
  • The hot, pressured refrigerant then travels from the compressor to the condenser and circulates in the accurate tubes of the condenser. This allows the refrigerant to cool down since the cooling fans blow cool air into the condenser. This cools down the refrigerant in the tubes of the condenser.
  • The cool but high pressured refrigerant then travels from the condenser to the receiver /drier. The receiver dries the refrigerant by removing any form of moisture. This makes the refrigerant cooler.
  • The cool, high pressured refrigerant flows into the expansion valve to reduce the pressure level while keeping it cooler. This enables the refrigerant to flow smoothly into the evaporator. By now we have cool, dry, and low-pressure refrigerant ready to do its job.
  • This cool, low-pressure liquid flows into the evaporator, and at the same time, the hot air from the cabin blows into the evaporator core (which has the cool refrigerant). Another heated exchange happens in this step. The refrigerant in the evaporator pipes exchanges heats with the air from outside. After that, the fans take the cool air and blow it into the air vents in the cabin.
  • The hot, low-pressure refrigerant then goes back to the compressor to start another cycle.

For more info, I recommend watching this YouTube video 

Common Causes Why is My Car Air Conditioner Not Blowing Cold Air?

Refrigerant Leakage

The main source of AC problems is refrigerant leakage. This can happen at any of the circuit components or the connection between them. The most common place where you can find leakage is in the external condenser. This could be due to any accident dent in the fluffy fins. You may locate the leakage by smearing some oil on it.

Bad Cooling Fans

Bad cooling fans can have a negative effect on cooling down the hot refrigerant that comes from the compressor.  The hot refrigerant needs to cool down by flowing inside the condenser due to the impact of the fans blowing the cold air.

Bad Compressor

The bad compressor prevents a successful refrigerant flow through the AC circuit, and as a result, you will not get cold air. The common mistake which damages the compressor is leaving it for long periods without use. You can, for instance, leave the AC during the winter without turning it on.

Blocked Condenser

This might be one of the reasons why there is no cold air blowing out of the air vents. A blocked condenser could be as a result of passing by a car in mud or sludge in the pipes. This will cause a barrier between the refrigerant and the cold blowing air by cooling fans. It eventually prevents the refrigerant from cooling down.

Electrical Issues

For the cooling fan to work at its maximum speed to cool down the engine while turning AC on, and also give the refrigerant the cool it needs to operate an order must come from the ECU. It then goes to the fuse box to magnetize a relay that turns on the fan at an appropriate speed. Turning on the AC, therefore, involve many electrical systems that need to be in perfect condition to operate as expected. Any failure in the circuits such as a bad relay will not connect the signals to the fans. This will then prevent good ventilation to the engine, making it heat up.

Bad Clutch Cycling Switch

This is an essential component of the AC system. It is located in the low-pressure area in the AC. Its job is to measure the pressure of the refrigerant flow in the system. When it detects a drop in pressure below a certain level, the switch allows pressure flow to the low-pressure area to equal the pressure in the system. If this switch happens to have a problem such as bad contact or any other electrical fault, it will affect the whole process. This is because the switch is responsible for having a stable pressure in the AC circuit.

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How to Fix Car AC Not Blowing Cold Air:

We have now learned how the car AC works and the common causes of why car air condition is not blowing cold air. Here, we shall learn how to fix car AC when it is not blowing cold air. We shall look at the symptoms or what drivers report and complain about and how to solve the issues:

how to fix car ac

“After turning on the AC I notice that the car became so hot and the temperature gauge is pointing to H”: This is a prevalent complaint about the car AC. In this case, you should know that the cooling fans are not working as expected. The fans cannot stand the high load on the engine after turning on the AC. You, therefore, need to check the fan motors are working. Also, check the fuse box and the fan relay. If you see the problem, change what needs to be changed.

“When I operate the AC I can hear the ticking sound of turning on the Compressor very frequently”: This happens when the level of refrigerant is less than it should be. It could be a refrigerant leakage in the condenser or the links between pipes. In this case, locate the leakage first by checking the condenser and the inlet and outlet pipes. You can use soap water and trace the bubbles to find the leakage spot.

“Car ac not blowing cold air when hot outside” or “car ac not cold enough”: This happens due to two reasons. One of them is the low quantity of the refrigerant, which prevents the refrigerant from absorbing the coldness as required. The other reason could be the blockage of the condenser, which reduces the amount of refrigerant passing by in a certain cycle. The solution to this is to drain the entire refrigerant using a proper device dedicated for this purpose. You then need to charge the AC with a certified brand refrigerant. Always check if your compressor supports the type. Do not forget to check the capacity of the charge.

“Car AC stopped working suddenly” or “car AC stopped blowing cold air all of a sudden”: This could happen due to a failure in the compressor. It could be a result of using the wrong refrigerant type or failure in the drive belt of the car

Some people also complain that car AC is not blowing cold air after recharge. The problem may be caused by the wrong capacity of the charge or the difference in the type of refrigerant. If this is the case, I recommend you have it fixed immediately to protect the AC parts from failure, especially the compressor.

Final Words:

After reading this article, you now understand the AC system, how it works, the parts of your car related to the AC system, and how to diagnose most of the faults in the AC systems. AC faults are very delusive since it involves many parts. One of the easy ways to maintain the cold air in the cabin is to change the cabin/Ac filter periodically. This will keep the evaporator clean and free from clogs. If you feel that you have a problem and you cannot diagnose it by yourself, it is better to seek help from a professional.

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Osuagwu Solomon

Osuagwu Solomon is a certified mechanic with over a decade of experience in the mechanic garage, and he has over five years of experience in the writing industry. He started writing automotive articles to share his garage experience with car enthusiasts and armature mechanics. If he is not in the garage fixing challenging mechanical problems, he is writing automotive repair guides, buyer’s guides, and car and tools comparisons.

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