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 Car Air Conditioning Works?
Though AC systems have become more sophisticated over the years, with some offering up to four zones of individual temperature control, the basic air conditioning technology remains more or less the same.
- The system uses a compressor driven by a pulley connected to the engine or, in electric cars, an electric motor attached directly to the compressor.
- The compressor compresses low-pressure refrigerant gas to a high pressure.
- The pressurized refrigerant gas flows into the condenser behind the car’s front grille, where a twisting tube system cools the refrigerant into a high-pressure liquid.
- The high-pressure liquid refrigerant moves through an accumulator or receiver dryer, which removes any water that might damage the system.
- The high-pressure fluid passes through an orifice tube or expansion valve. This allows the refrigerant to expand and cool to move to the evaporator core as a near-freezing low-pressure liquid. In the evaporator, the liquid converts back to a low-pressure gas.
- A fan blows air over the evaporator and sends the cool air into the passenger compartment.
- The low-pressure refrigerant gas flows back into the compressor where the process begins over again.
Common Causes Why is My Car Air Conditioner Not Blowing Cold Air?
The most common reason why your AC is not blowing cold air is due to an empty AC system, which is caused by a leak.
It can also be caused by a faulty AC pressure switch, a bad compressor, or a damaged AC condenser. In more rare cases, it can also be an issue with your heat controller.
The main issues that occur with the car’s air conditioning system are due to poor maintenance. Here is a more detailed list of the most common causes of a car AC not blowing cold air.
#1. Empty AC System.
Your AC system is filled with an ac refrigerant, making sure the whole system is working correctly. This refrigerant system is under high pressure, and it can reach 15 bars when the car is running.
For the AC system to work properly, it needs this pressure and a specific amount of refrigerant.
If you leak in the AC system, the pressure will get lower and lower, until it finally stops working at all.
The AC system also leaks very slowly through hoses and other places. This is an extremely slow process, though, and you can expect to refill it every 6-7 years.
If you haven’t refilled it in 6-7 years, it is definitely time for a refill. If you filled it more recently than that, it is time to check it for leaks.
Only let a certified workshop with the proper equipment do work to your AC system. The AC system should always be checked for leaks before a refill.
#2. Faulty AC Pressure Switch.
There are two AC pressure switches in your car that monitor the high-pressure side and the low-pressure side of the air condition system for safety reasons.
If the pressure gets too high, it will stop the AC compressor from cooling the system anymore. This is a safety mechanism. The same is true if the pressure gets too low.
If the AC pressure switch is faulty, it can give the AC compressor faulty signals to stop – even if it shouldn’t – and this will cause your AC system not to function at all.
#3. Faulty AC Compressor Clutch.
Some car compressors use a clutch inside the air compressor. The serpentine belt powers the air compressor pulley, and when you activate the AC, the clutch connects the air compressor to the pulley.
This makes the AC compressor to spin and power the AC system. If this clutch is too worn, it may cause the AC compressor not to start at all. You can replace this clutch in many AC compressors, or even remove shims for the clutch for it to work a little bit more.
Most newer cars have a variable AC compressor, though, and in this case, no AC compressor clutch can fail.
#4. Faulty AC Compressor.
The AC compressor clutch isn’t the only thing that can be damaged. The compressor itself can also fail if you are unlucky.
The AC compressor pumps refrigerant around in the AC system for it to cool properly. Occasionally, the pump fails and stops pumping at all, and this will cause your AC system to blow hot air.
If the AC compressor fails, you often have to flush the whole AC system afterward, because there might be metal pieces everywhere.
#5. Damaged AC Condenser.
The condenser is installed in the front of the car, and it transfers heat away from the evaporator inside the car.
The AC condenser is often installed in front of the radiator, and this means it sits in a very exposed position. Stones and other pieces of detritus can damage it when your car is traveling at high speeds.
This often causes the AC condenser to start leaking refrigerant. You will usually need to replace the AC condenser at least once every 10 years.
#6. Damaged Condenser Fan.
The condenser needs wind passing through it to remove the heat properly. As you might imagine, wind won’t pass through naturally if your car is moving at a low speed. For this, your car needs a fan so that air is pushed through even when your car is moving slowly.
If this fan fails, there might be a problem with the AC system at lower speeds. If you notice that your AC is working at higher speeds, but not at lower ones, there could definitely be a problem with the condenser fan.
#7. Clogged Cabin Filter.
The cabin air filter is responsible for filtering the air that enters the vehicle’s air conditioning system. The filter catches all the dust and impurities that enter the passenger compartment and can, therefore, become clogged over time.
Also, a clogged cabin air filter leads to a deterioration in the air conditioning system’s cooling. It is recommended to check and clean the cabin air filter frequently.
If you feel that there is a meager amount of air blowing through the vents, it could absolutely be a clogged air filter.
#8. Faulty Blend Door Actuator.
When you turn the heat controller on the AC control unit, there needs to be something that controls the heat inside the car. This part is called the blend door actuator, and it controls a flap that redirects hot or cold air inside of your car.
The setup can look a little bit different from car to car, but the main function is the same. If this actuator is faulty, your car might blow hot air out from the vents even if you need cold air.
#9. Faulty Heat Controller / Air Condition Control Unit.
The last cause on this list is a faulty heat controller. If this fails, it may send the wrong signal to the blend door actuator, and this may cause it to blow hot air instead of cold.
Most older cars have wires for this, but newer cars have an electronic signal between these, which can fail. The air conditioning control unit is often quite expensive. You should check the other possible causes on this list before deciding to replace it.
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:
#1. Check the Refrigerant Level.
The first thing you should do is check the AC refrigerant. Refrigerant is the chemical that makes your AC blow cold air.
If it is low, the AC will only blow warm air. To check, you can use a gauge or take it to a shop. Sometimes a small leak causes low refrigerant, so it needs fixing too.
If you notice bubbles or hissing sounds when checking, that usually means a leak. Don’t ignore it because adding refrigerant without fixing a leak is temporary. Also, the color of the refrigerant can show if it is old or dirty.
New refrigerant is usually clear or light green. Old or contaminated refrigerant can make the AC inefficient.
When adding refrigerant, follow the instructions carefully. Overfilling can damage the system. Make sure the car is on and AC is running while refilling. Test the air after refilling; it should feel colder in a few minutes.
Check for leaks using soap water on connections if you do it yourself. Bubbles mean there is a leak. Fixing small leaks can be done with sealant, but bigger leaks need professional help. Always use gloves and safety glasses when working with refrigerant.
- Refrigerant low? Check with a gauge or shop
- Look for leaks by hissing sounds or soap bubbles
- Refill carefully; don’t overfill
- Test AC after refilling
#2. Inspect the AC Compressor.
Your AC compressor is like the heart of the system. If it is not working, air won’t get cold. First, check if the compressor clutch is moving when AC is on. If not, there could be an electrical issue or a mechanical failure. Sometimes it is just a blown fuse.
Listen for strange noises. Clicking or grinding can mean internal damage. A bad compressor often reduces airflow or stops cold air completely. Also, check the belts connected to the compressor. Worn or broken belts can stop it from spinning.
Electrical issues can be simple. Check fuses and wiring for damage. A multimeter can help test voltage. If the compressor is completely broken, replacement is usually the only option. It is expensive, but necessary to restore cooling.
Sometimes the compressor works but the pressure is wrong. High or low pressure can indicate a problem in the system. You might need professional help to measure pressure accurately. Proper maintenance helps prevent future compressor problems.
- Check compressor clutch movement
- Listen for strange noises
- Inspect belts and wiring
- Test pressure with a professional tool
#3. Clean or Replace the Cabin Air Filter.
A dirty cabin air filter can block airflow and make your AC seem weak. The filter is usually behind the glove box or under the dashboard. Check it every year or 12,000 miles, whichever comes first. A clogged filter can also make the AC work harder, reducing its life.
Removing the filter is simple. Open the compartment, pull out the old filter, and check for dirt or leaves. Replace it with a new one if it looks dirty. Make sure it fits snugly and is installed the right way.
A clean filter improves airflow and efficiency. It can also reduce bad smells from mold or dust. Even if your AC seems fine, changing the filter is an easy way to prevent problems. Sometimes, people forget this small step and wonder why AC is not cold.
Always use the correct filter type for your car. Cheap filters may not trap dust well. Also, consider checking the evaporator behind the filter. Dust and dirt on the evaporator can reduce cooling and airflow.
- Locate and check cabin filter
- Replace if dirty or clogged
- Ensure proper fit and direction
- Inspect evaporator for dust
#4. Examine the AC Condenser.
The condenser works like a radiator to cool the refrigerant. If it is blocked, the system can’t cool properly. Check for dirt, leaves, or bugs on the front of the condenser. A clogged condenser often leads to warm air coming from vents.
Cleaning is usually easy. Use a hose and gently spray water to remove debris. Avoid strong pressure because it can damage fins. For more serious buildup, a soft brush can help. Make sure nothing blocks airflow to the condenser.
Leaks in the condenser can also reduce cooling. Look for oily spots or wet areas on the condenser. If you see them, professional repair is recommended. Some small leaks can be sealed, but most require replacement.
After cleaning or fixing leaks, test the AC. If airflow improves and air is colder, the condenser was likely the problem. Regularly checking it can prevent big issues in hot weather.
- Inspect condenser for dirt or leaves
- Clean gently with water or brush
- Check for leaks or wet spots
- Test AC after cleaning
#5. Check the AC Blower Motor.
The blower motor pushes air into the cabin. If it is failing, you may feel weak airflow or no air at all. Listen for strange noises like squealing or rattling when turning on AC. If the motor is dead, only repair or replacement works.
Sometimes, the issue is not the motor itself but the resistor. The resistor controls speed settings. If speed settings don’t work correctly, check the resistor. Also, fuses and wiring should be inspected for damage.
Replacing a blower motor is not too difficult for many cars. Usually, it is under the dashboard on the passenger side. Disconnect the wiring, remove screws, and slide the motor out. Install the new one carefully and reconnect wiring.
After replacement, test the fan at all speeds. Make sure air blows strongly and consistently. Regular checks of the blower motor help prevent sudden failure in hot weather.
- Listen for motor noises
- Check resistor and fuses
- Replace motor if needed
- Test airflow at all speeds
#6. Inspect the AC Electrical System.
Modern cars rely on electronics to control AC. A small electrical problem can stop cold air. Check fuses, relays, and wiring for damage. Sometimes a loose connection or corrosion is the cause.
The AC control panel can also fail. Buttons may not respond or settings may jump. If this happens, test with a multimeter or seek professional help. Electrical issues can be tricky and dangerous.
Relays are small switches that power the compressor or fan. If a relay is bad, the system may act strangely. Swapping a relay with a known good one can quickly test it. Also, check ground wires for corrosion.
After inspecting everything, test the AC system. Make sure air is cold and airflow is normal. Fixing small electrical problems early prevents bigger repairs later.
- Check fuses, relays, and wiring
- Inspect control panel functionality
- Test relays with a known good one
- Ensure proper grounding and connections
FAQs.
Q: Why is my car AC not cooling?
Your car’s AC may not cool because of refrigerant loss, a clogged condenser, or a faulty compressor. Check for leaks in the system. Make sure the condenser is clean. If problems continue, see a mechanic for a full diagnosis and repair.
Q: How can I check AC refrigerant levels?
To check refrigerant levels, use a pressure gauge on the AC service ports. Compare the readings to standard values. If levels are low, you may need a recharge. Handle refrigerant carefully, as it can be dangerous. Seek professional help if you are unsure.
Q: What causes AC compressor failure?
AC compressor failure can happen due to low refrigerant, electrical problems, or wear and tear.
Regular maintenance helps avoid these issues. Look out for unusual noises or leaks. If the compressor fails, replacing it with a new one is the best option for optimal performance.
Q: How do I clean my car AC condenser?
To clean the AC condenser, start by removing debris with a soft brush. For tough dirt, use water and mild detergent. Make sure the condenser is completely dry before using it. Regular cleaning helps the system work better and lasts longer.
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.