Home Diagnosis and TroubleshootingClimate Control and Air Conditioning Car AC Not Blowing Cold Air? Troubleshoot Here

Car AC Not Blowing Cold Air? Troubleshoot Here

by Jordan Harris
Car AC Not Blowing Cold Air

The air conditioning in a car is a blessing most of us take for granted. Decades ago, air conditioning was a luxury amenity available in an elite bunch of automobiles. But now, it has become a staple in almost all vehicles, even in the developing markets of the world. But what if your car AC is not blowing cold air?

When the AC is not blowing cold air, the importance of having properly functioning air conditioning becomes clear to us. We have all been there and done that.

But what makes an AC give up? How do you end up with an AC not blowing cold air? How do you troubleshoot it? And how do you correct it? In the next few moments, we will get down to the nitty-gritty of this issue and list out ways to correct it.

To understand why your AC is not blowing cold air, it is necessary to have a basic understanding of the functioning of the air conditioning system. Let us give that a glance before we dive deep into our subject.

How Does The AC Of A Car Work?

Air conditioning is one of the systems that car users use almost every time they use their vehicle. You can never ignore the importance of this system in elevating your driving experience.

The air conditioning system is built up of multiple components. Any of these can be a reason why your AC is not blowing cold air (and learn how to make car AC colder). Let us look at every one of those systems in detail.


Powered by the engine via the serpentine belt, the compressor plays a key role in initiating the air conditioning process. It is the workhorse of the air conditioning system. The compressor is employed to pressurize the refrigerant and turn it into a high-pressure, high-temperature gas.

An AC compressor clutch engages the compressor when you turn on the air conditioning. Multiple pistons inside it which can compress the refrigerant.


This is similar in function to the radiator of the vehicle. The condenser receives the pressurized refrigerant from the compressor. This runs through several channels within the condenser. Cool air flows into the condenser to condense this gas. The gas converts to a high-pressure liquid, which is then led out of the condenser.


Moisture is the worst enemy of the air conditioning system as it can corrode its components. To remove any remaining moisture in the refrigerant, car air conditioning systems employ a device named Accumulator/Dryer. A desiccant material finds room inside the accumulator/dryer. This takes away the moisture from the refrigerant before it flows into the evaporator.

Expansion Valve

Before the refrigerant reaches the evaporator, it flows through a Thermal Expansion Valve.

The high-pressure liquid refrigerant that flows out of the condenser meets the expansion valve right before the evaporator. The expansion valve has a tiny hole in it. When the high-pressure liquid refrigerant squeezes through it, it boils immediately. This turns the refrigerant into a low-temperature gas that is then fed into the evaporator for cooling the air. The expansion valve also serves as the middle point of the air conditioning system where the high-pressure parts end and the low-pressure parts begin.


The evaporator is a device similar in construction to the radiator, with channels for the cold gas to travel through. This is responsible for cooling down the air that flows into the cabin.

Heater Fan

This is a simple fan located in front of the evaporator. This fan blows the ambient air through the evaporator, and to the cabin. The flowing air gets cooled as it passes through the evaporator. This cold air cools down the cabin and gives you a comfortable ride.

If you want a detailed explanation of the air conditioning system in a car, you can refer to this video which explains each part and its function.

Why Is Your AC Not Blowing Cold Air?

The most common answer to this question is either a compressor failure or leaks in the coolant system. But these are not all, car AC not blowing cold air can be caused by many other issues as well.

AC Has Run Out Of Charge

A common problem that many car users face is their AC running out of charge. This is not a problem per se. It is more of a routine maintenance procedure that must be done after using the car for a long period.

Just like other fluids in your car, the air conditioning refrigerant runs out after many years of use. This needs to be recharged or refilled. Else, it can end up being a reason for your AC not blowing cold air.

Recharging the air conditioning is not a beginner’s task so it is always better to take your vehicle to a garage to get it done. But if you feel adventurous, do-it-yourself refrigerant kits are available in the market. These help you recharge your AC yourself.

Watch this video to understand how these DIY kits work, and how to use them.

Refrigerant Leaks

This is an issue that can lead to the air conditioning system running out of charge. The refrigerant flows through your AC system at high pressures thus even a small leak can be a quick escape for the whole refrigerant. The nature of the refrigerant itself makes it even worse. It evaporates instantly after coming to contact with air.

If you see your refrigerant levels dropping drastically even after a recharge, you can be certain that there is a leak somewhere in the system. Several other signs also point at a possible leak, like an audible click when you turn on the AC, AC switching between ON and OFF, making hissing sounds when the vehicle is turned off, and some oil residue around the pipes and AC hoses.

If these symptoms suggest that you have an AC refrigerant leak, take the help of a professional AC mechanic to pinpoint and alleviate the leak. This is no rookie task as you need specialized tools to spot the leak. Mechanics introduce ultraviolet fluids into the system using these tools to find the leak in the system by showing a pressure drop.

If you still feel adventurous and dares to do it yourself, we suggest not to. Not only the job is hard to do, but it can also cause physical harm if not properly done. The refrigerant is a very toxic substance. Most modern vehicles use a type of refrigerant named R134a. This compound uses Tetrafluoroethane (CF3CH2F), a chemical that can cause serious harm if inhaled. There are other types of refrigerants too, which this list details.

Electrical Issues

As your car air conditioning has electrical components, all gremlins that affect your car’s electrics affect them too. This can include anything from a blown fuse to a short circuit. Common electrical issues exist in the electrical control systems of the air conditioning system, especially if you have an automatic climate control-equipped vehicle.

To diagnose this issue, you can use a test light to ensure that power is adequately being sent into the AC compressor relay. The failure of any control component inside the cabin can block the power supply to this unit. Refer to your owner’s manual to find out where the relay is located inside the fuse box.

After locating the relay, use the test light to test the terminals while you have turned your AC on. If it is detecting an electrical flow, this means that the relay is getting powered by the battery. As this relay engages the compressor clutch, it must function properly. Mechanics use a relay switch in place of the actual relay to test if power is being sent from the relay to the compressor clutch. If it is engaging/disengaging the clutch, the electrical part of your vehicle’s AC should be mostly fine.

But if there is an issue, you will need help. Depending on the issue that is plaguing your AC, the costs for repair can vary. For repairing your electricals, seek the help of a professional.

AC Compressor Failure

The compressor in the air conditioning plays an important role in its functioning. The compressor is responsible for keeping the refrigerant at higher pressures before it reaches the condenser. This essential part can fail due to many reasons. Any leakage in the refrigerant lines or short circuit in the electrical system can end up in a malfunctioning compressor.

A broken compressor renders the air conditioning unable to pressurize the refrigerant. The pressure drop will bring down the effectiveness of the air conditioning. This can be a possible explanation for your car AC not blowing cold air.

Given its complexity in diagnosis as well as just reaching the compressor, it is no rookie job to rectify this issue. This problem can only be resolved only by a pair of seasoned hands. You can refer to this story here to understand more about the compressor replacement procedure as well as the costs tagged to it.

Also, removing the compressor needs removing the serpentine belt. Refitting this must be done carefully as an improperly tensioned belt can end up creating malfunctioning in many components.

If you wish to know more about serpentine belts, or other forms of drive belts, this video is a very reliable source

AC Condenser Failure

As we have already established, condensers in air conditioning systems play an important role. They bring down the temperature of the pressurized refrigerant using ambient air, converting it from a gaseous state to a liquid state. Any glitch in this operation can bring down the operating efficiency of the air conditioning system.

The main condenser-related issue that leaves your car AC not blowing cold air is a change in its physical structure. The condenser placed at the aft end of the vehicle gets blocked or even damaged by debris from the road. It can also get itself blocked due to dirt buildup, especially after a drive-through slush.

Physically inspecting the condenser is the only way to see if it is blocked by debris in any way. If found to have dirt buildup, get the condenser cleaned, and inspect for any physical damage. If it is all well and good, you should be good to roll.

Condenser Fan Failure

Another condenser-related issue that can render your car AC not blowing cold air is the failure of the condenser fan. The condenser fan performs the important duty of pulling the ambient air into the condenser, cooling the flowing refrigerant gas down.

Any failure in the operation of the fan can hamper the process of the air conditioning system. The condenser will not get adequate cooling and your car will not blow cold air. The gremlins that render the fan useless can be dirt/dust buildup that chokes the fan, a blown fuse, or any other electrical problem.

The repair process for this issue can be daunting for a newbie. Removing the condenser fan is a complex task. So if your hands have not seen enough grease, get a professional to replace them for you.

Faulty Expansion Valve

The expansion valve is a key element of the AC that sits at the inlet of the evaporator, regulating the flow of the refrigerant. It cools and lets in the right amount of refrigerant, based on the cooling requirements and load. Anything more, the evaporator can freeze over. Letting in less refrigerant can leave your car AC not blowing cold air.

The symptoms that point at a potential expansion valve failure is, of course, an underperforming AC system. The expansion valve can fail and not let in enough refrigerant; hence you will get hot air from the vents.

On the other hand, if the expansion valve stays open, it can pump in refrigerant, even when it is not needed. In these cases, the other components of the AC will be put under unwanted load at all times, reducing their longevity as well.

Replacing an AC expansion valve is a tricky business. But this guide will hold your hand through it if your car is not blowing cold air and your expansion valve is the one to blame.

Faulty Drier/Accumulator

The accumulator of an air conditioner plays a vital role in keeping moisture away from the internal components. Moisture entering the system can cause large issues including corrosion. To keep the moisture away, these components use special desiccants.

Car AC Not Blowing Cold Air

Can you guess what is more dangerous than water if it enters the compressor? The desiccant keeps the moisture away. Any failure in the drier/accumulator can cause the desiccants to enter the AC system. This saturation of the desiccant material can cause problems to the compressor.

Getting your accumulator/drier checked is a good idea to maintain the health of your air conditioning system. This can avoid some situations in which your car AC is not blowing cold air.

Stuck Blend Air Door

The blend air door acts as a valve that prevents the warm air around the engine from flowing into the cabin. The moment air conditioning is turned on, the blend air door closes off the warm air from flowing into the cabin. This helps the cool air to flow into the cabin, cooling it down.

If the blend air door gets stuck, the warm air from around the engine flows into the cabin. No matter how well your air conditioning is functioning, you will still end up with your car AC not blowing cold air. Fixing the blend air door is no biggie but getting to it is a task on its own. Blend air doors are usually mounted deep inside the dashboard. This may need expert eyes and hands to reach and repair.

Car AC Not Blowing Cold Air: How Much Will It Cost To Repair?

Depending on the complexity of the repair, the prices can range from $150 to $700 for minor repair and well over thousands for major repairs. A simple recharge of refrigerant can set you back around $100 to $140. You can use services like Wrench, Yourmechanic, or Openbay for a reliable quote. Connecting with your trusted neighborhood garage will also fetch you a good deal.

This guide can give you a better insight into the repair procedures as well as the costs related to them.

How To Keep Your AC Healthy?

Irrespective of the form and function, every part of your car needs complete care and maintenance to perform at its best. The air conditioning system is no different from it. Proper maintenance will ensure the smooth functioning of the AC system in your car. This will get rid of any situations in which your car is not blowing cold air.

There are a few steps that you can take to ensure the longevity of your air conditioning system.

Run It At Least Once A Week

Possibly the easiest step to do in this list. Your car’s AC is designed to function for long intervals. But, if it is left without functioning for a while, it can develop failures. Just like every other function of our car, the air conditioning needs to run to ensure its long-term health.

So, even during a cold season, leave your AC on for at least 10 minutes a week. This will help in maintaining gas pressure inside the system and allow the compressor to work properly. Ensure that the AC is set to its lowest temperature and highest fan speed as this procedure is performed.

This can be inconvenient during the harshest of winters, but you can perform this when your car is parked as well. You need not be inside the car for the whole duration. Make sure that it is at a location that is safe to leave the car started. You can also work the AC out by using the defogger function regularly.

Clean Your Cabin Air Filters

Though the skipping of this step will not end up with your car AC not blowing cold air, this is an important part of the AC maintenance procedure. The cabin air filter (and knowing how to replace cabin air filter) prevents dust and pollutants from entering your cabin through the AC vents.

Car AC not blowing cold air

A choked air filter can end up reducing the efficiency of the air conditioning. The cabin filters are easily accessible inside the cabin and can be easily replaced. You do not need professional help for replacing a cabin air filter. Just make sure that you procure the right filter for your vehicle.

Recharge Your AC Regularly

The very important stuff that most people forget is the recharging of refrigerants. Though your refrigerant can perform well for long years, it is suggested that you recharge it once every two years. This can keep your AC running fresh and avoid situations in which your car AC is not blowing cold air.

Service Your AC

If your car is quite old but your AC is still working well, this is a tip for you. Over time, the air conditioning systems in the cars can wear out their health, ending up with an inefficient flow. So, to sustain the current health of the AC in your vehicle, a complete AC service is recommended.

Trained mechanics perform these services with specialized tools. They can detect possible leaks and other damages to the system, even before they turn worse. This can help you foresee the damage and take an action accordingly. This can save more money in the long run than what you may spend on AC servicing. If done properly, you will not have to worry about your car AC not blowing cold air.

Car Air Conditioning: Facts You Need to Know

  1. The most common causes of broken air conditioning are leaks or compressor issues.
  2. If the air is blowing cool but not cold, the problem could be a clogged filter, cooling fan problem, radiator trouble, or the AC may need to be recharged.
  3. You can diagnose your car’s specific climate control problem by checking three things before going to the mechanic.
  4. To check for cooling fan restrictions, make sure the fans on the condenser or radiator are running when the air conditioning is on.
  5. Use a manifold gauge set to check the pressures in the system when diagnosing an air conditioning issue.
  6. If the AC compressor clutch is engaging and disengaging once every few seconds, this is a sign of low refrigerant.
  7. Leaks are the most common problem associated with the air conditioning system.
  8. Use a UV A/C leak detection kit to find leaks and check around fittings, hose manifolds on the compressor, front seal, and o-rings sealing the pressure switches on the back of some compressors, hoses crimped onto fittings, Schrader Valves, and pinholes in the condenser.
  9. The AC compressor, accumulator/drier, orifice tube/expansion valve, condenser, and evaporator core are the main components of the car’s air conditioning system.
  10. The common problems associated with these components and what to look for when diagnosing issues are listed here.

Wrapping it up

As we have already seen, car AC not blowing cold air is a common issue that can be tracked and rectified. But a silly oversight can end up breaking your bank.

Depending on the cause of the issue, the repair procedure can range from a little headache to a full-blown migraine. But with regular maintenance and upkeep of your car’s air conditioning system, you can avoid ending up in such a fix. Including the maintenance of your air conditioning system in your regular vehicle maintenance schedule can go a long way.

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