11 Reasons Your Car AC Blows Warm Air While Idling – Solve Car Air Conditioner Not Blowing Cold Air When Idle Puzzle

Car AC Not Cooling

Vehicle AC not cooling is a big issue in hot weather. Almost every air conditioner user faces this problem. It is no fun traveling in a car whose air conditioning system doesn’t blow cold air. Fixing the “Vehicle AC not cooling” issue is very important to protect yourself from discomfort and dizziness in the car.

In this powerful guide, you are going to quickly learn the eleven complete reasons for car AC blowing warm air while idling.

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What is Car Air Conditioning System

A car air conditioning system is a mechanism that cools the air inside a vehicle and removes excess moisture to provide comfort to the passengers. The system comprises several components, including a compressor, condenser, evaporator, expansion valve, and refrigerant, working together to maintain the desired temperature and humidity levels in the car.

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Car AC Blows Warm Air While Idling

The cooling system of the vehicle became an obligatory component of the car. Nowadays, hardly a car is manufactured without an air conditioner. The air conditioner provides comfort to the car owner and passengers.

Sometimes, automobile air conditioning gives poor cooling capacity. It happens due to many reasons, but for you, it is important to know the reasons why the car is not cooling enough. So, when you visit the workshop, you have confidence in yourself that the technician does not misguide you. Below are the eleven complete issues due to which automobile air conditioning not blowing cold air during engine idling.

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11 Reasons For Car AC Blows Warm Air While Idling

automobile air conditioning Blows heated air while Idling can be caused by many reasons. Below are the eleven complete reasons for a car’s cooling system not cooling.

  1. Refrigerant Leak
  2. Defective Compressor
  3. Clogged Condenser
  4. Faulty Condenser Cooling Fan
  5. Clogged Expansion Valve Or Orifice Tube
  6. Moisture In The cooling system System
  7. Clogged Evaporator
  8. Overfilled With Refrigerant
  9. Dirty Interior Filter of Air
  10. Worn Compressor Belt
  11. Overheated Engine

1. Refrigerant Leak

Inspecting The AC System
Inspecting The cooling system System

The biggest reason for the vehicle cooling system blowing hot air while the car is idle, is due to low refrigerant levels.

“According to air conditioning expert of the society of automotive engineers (SAE) Ward Atkinson says, the A/C system is not fully airtight, It is nearly airtight. Refrigerants always trying to escape from the system.

Ward Atkinson

“O” ring seals and hosepipes lose their elasticity with time, which forces refrigerant to escape from the cooling system. Therefore, the automobile air conditioning will fail to provide cool air when the outside air temperature gets warm.

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2. Defective Compressor

Seized Compressor
Seized Compressor

A defective compressor is a common reason for automobile air conditioning to start blowing heated air. Sometimes, the

air conditioning system in your car does not work properly due to a lack of lubricating oil, which escapes with a refrigerant leak. Without enough lubricating oil, the ac compressor may seize and becomes defective.

As a result, the compressor will not compress the refrigerant properly, which leads to poor automobile air conditioning cooling. Lubricating oil is necessary for a compressor smooth running.

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3. Clogged Condenser

Clogged Condenser

Sometimes vehicle’s cooling system does not operate correctly at idle due to a clogged ac condenser. Dust and leaves gather on the surface of the condenser causing condenser blocking and air obstruction. So, a blocked condenser will not dissipate much heat resulting in warmer air.

4. Faulty Condenser Cooling Fan

Condenser Cooling Fan
Condenser Cooling Fan

The condenser cooling fan sits on the condenser. It makes the refrigerant cool when the refrigerant flows in condenser tubes. So, If you turn on the AC during hot weather, a faulty AC cooling fan can prevent the car’s AC from blowing cold air.

Some condensers release heat by the natural air passing through them while driving, either by the forward motion of the vehicle or by fans that actively force air through the condenser. A faulty or dead condenser cooling fan will not run and dissipate enough heat from the condenser when it is hot outside. Therefore, when the ambient air temperature increases the vehicle cooling system will not release cold air when you’re moving. So, make sure you have a good working condenser fan.

5. Clogged Expansion Valve Or Orifice Tube

Expansion Valve
Expansion Valve

A blocked expansion valve or orifice tube is also a common reason for a vehicle A/C not getting very cold at idle.

The expansion valve and orifice tube convert refrigerant from liquid to vapor state. When metal particles accumulate in the expansion valve, they cannot operate fully in an excellent way. Therefore, the valve remains stuck in an open or closed position due to which the car runs with heated air.

6. Moisture In The Air cooling System

Moisture is a common reason for vehicle air conditioning throwing heated air while idling. It is the poison of the cooling system. It can react with lubricating oil and forms formic acid, which slowly deteriorates the whole cooling system’s performance. So, a moisturized cooling system will not cool the car properly, especially when the air from outside is hot.

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7. Clogged Evaporator

Clogged Evaporator In Car AC
Clogged Evaporator In vehicle air conditioning

Unlike, the condenser that releases heat from the refrigerant, the evaporator adds heat to the refrigerant. It works oppositely as the condenser does.

If your car’s air conditioning doesn’t blow cold air when your car is moving, the issue may be related to the evaporator. The evaporator absorbs the heat from the inside of the car and makes the interior air cool. A blocked or leaked evaporator will not provide enough air from the interior and as a result, the ac will not blow cold air.

8. Overfilled With Refrigerant

AC Overcharge With Refrigerant
cooling system Overcharge With Refrigerant

Overcharging is also a usual reason for vehicle cooling system does not cool the air in hot weather. Refrigerant overloading can increase the pressure on the low-pressure side by liquid running too far into the evaporator.

This phenomenon makes the low-pressure side a low-sucking side. This decreases the cooling performance of the vehicle cooling system and eventually, the hot air will blow out of the vents.

9. Dirty Cabin Air Filter

Clogged Air Filter Of Car AC
Clogged filter of air Of Cooling System of vehicle

The air conditioning system works well with a clean filter. A dirty filter of air is a reason for the vehicle’s A/C system not cooling properly. It filters the debris and pollens from the air to make the interior air clean and healthy. A dirty filter of air will not allow enough air flow, therefore, maximum air will not move across the evaporator, which leads to poor cooling of the car cooling system.

10. Worn Compressor Belt

Worn AC Belt Of A Car
Worn Air Conditioning Belt Of A Car

If the air blowing is warm when you turn the ac on then ac may be defective due to a worn-out belt. The serpentine belt has an important function in running the compressor.

The compressor consumes a lot of power from the engine. If the compressor belt is worn, weak, or loose by constant usage. The compressor belt will slip when ac starts, and will not rotate as it should, forcing the A/C not to blow cool air.

11. Overheated Engine

Overheated Engine
Overheated Engine

An overheated engine is also a big factor in vehicle A/C system isn’t blowing cold air. The Car ac throws cool air if the engine is not too warm. An overheated engine produces too much heat, which affects the cooling capacity of the condenser cooling fan. As a result, the vehicle AC will not blow cold air properly.

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How To Fix Car AC Not Blowing Cold Air When Idle

Here are a few steps you can follow to fix your vehicle’s A/C system if the air is blowing warm at idle position:

  • Check The Refrigerant Level: A low refrigerant level can cause the A/C to blow heated air. If the refrigerant level is low, it needs to be recharged.
  • Inspect The Compressor Of Cooling System: If the AC compressor is not functioning properly, it may blow gentle air. Check the belt for cracks or damage, and inspect the clutch for any issues.
  • Check The Condenser: When the ac starts blowing warm air, it may be a sign of a clogged condenser. Which can reduce the performance of the cooling system. Clean the condenser to improve its performance.
  • Examine The Evaporator: If the evaporator is dirty or clogged, it will also reduce the performance of the cooling system, due to which air gets warmer. Clean the evaporator to get hot to cold air.
  • Inspect The Fans: The fans play a crucial role in the performance of the A/C system. You will not receive cooler air if the fans are not functioning properly. Check the fans and their motors for any issues.
  • Leaks In The Cooling System: Leaks in the cooling system can cause refrigerant to escape, resulting in the A/C blowing heated air. To fix this issue, check for refrigerant leaks, which must be located and repaired by a professional.”

Note: It is recommended to consult with a professional mechanic to help with your car issue if you are not experienced in fixing Vehicle A/C systems.


In conclusion, an AC emitting warm air while idling is an annoying problem, but it can usually be fixed without too much effort. After checking all of the potential causes listed above, if your car A/C still isn’t emitting cold air when you’re idle, then it’s time to take your vehicle to a professional mechanic. Proper maintenance and regular checks can help prevent future issues with your car’s A/C system. Regularly replacing the cabin filter can help keep your car’s A/C system running smoothly and efficiently.

Frequently Asked Questions (FAQs)

Will the temperature of air inside the car change when the car is not moving?

The temperature of the air inside a car can change when the car is not moving, but it depends on various factors such as the outside temperature, the amount of sunlight entering the car, and the insulation of the car.

Is it better to use the air control while driving at high speed when the temperature of air is getting cold?

It depends on the preference of the driver. If they want to regulate the temperature of air, they can use the system to control the air system to adjust it to their desired level. However, if they prefer to blow ice cold air, they may not need to use the system to control the air while driving.

Does the air throwing from the AC feel colder at high speeds while driving?

Yes, the air throwing from the AC can feel colder at high speeds while driving because the air is coming into contact with more hot surfaces, making it easier for the chilled air blowing to lower the overall temperature of air inside the car.

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