How To Recharge Your Car’s Ac?

Does your car AC stop blowing cold air? Is it warm like or hotter than the ambient temperature? When a car AC stops blowing cold air as it’s supposed to, it is a sign of a system leak or low Freon. At such a point, it is essential to check for system leaks and recharge the refrigerant.

Contrary to the idea that air conditioning systems transport cold air into the cabin, it expels the heat from the ambient air, making it less hot or colder. It accomplishes this with a set of vital components, like a condenser and compressor, which depends on refrigerants to generate cold air.

The most common reason for an AC system to blow warm air is low refrigerant. And if you know how to recharge car AC, the fruit is an ever-present icy feeling when driving in summer. Thanks to the RXmechanic team, here you learn what you need, what to do, and how to do it.

How Do I Know If My Car AC Needs To Be Recharged?

Modern air conditioning systems work with compressors, which run with refrigerants and oil through the system to generate icy air. Every AC system has two lines – the high-pressure lines and the low-pressure lines. 

The refrigerant gets circulated as a gas from the low-pressure line and converts into a liquid state before passing through the high-pressure line. The constant circulation of refrigerant from the low and high-pressure lines keeps the home and car air conditioner cold.

You’ll agree, the air conditioning system is pressurized. And for this reason, they are properly sealed. Under normal usage and over time, the seals in the system will develop leaks. Once a leak occurs on the system, it’ll leak out the refrigerant over time. This will make the AC unable to produce cold air.

When this happens, you’ll need to recharge the AC for it to function as it should. However, like other system components, the AC system will display some signs to notify the driver to recharge it.

how to recharge ac in car (r134a)

AC not blowing cold air

The air condition system functions by circulating refrigerant on the AC system components. So, if the level drops too low, it will not function properly leading to the inability of or insufficient cold air generation.

You’ll notice warm air coming from the air vents instead of cold air. You can check out this article for other reasons AC is not blowing cold air.

AC clutch not engaging

When you set your AC to max cold settings, you should hear clicking sounds that show the clutch is engaging. The AC pressure switch, which reads the system pressure, signals the clutch to engage.

With too low refrigerant in the system, the pressure switch will not keep active. This will also make the AC clutch not engaging. As a result, the system will not circulate the low refrigerant, making the air conditioning system not working at all.

Refrigerant leaks

More serious evidence that you need recharging ac in a car is refrigerant leaks. If you notice any greasy substance on the AC fittings, joints, or see pools of refrigerants on the AC components, it’s a clear sign of system leakage.

Of course, system leaks mean loss of refrigerant. The leak will continue until all the refrigerants evaporate out of the system.

It is important to note that recharging an AC system with leaks will not address the issue. Instead, you’ll need to fix the leak before recharging the car AC.

If you notice these signs and suspect your air conditioning system needs a recharge, inspect the system for leaks before recharging it. Read this article on how to make a car AC colder.

What’s next? Let’s look at how to recharge car AC in the following few paragraphs.

Tools and Gears Needed To Recharge Car AC

Recharging car AC is pretty simple. However, working on cars can be dangerous and messy. So you need some safety gear when recharging car Ac in cars and homes. Here are the safety gears to keep you safe.

  • Safety glasses
  • Mechanic glove.

Aside from the safety gears, before you start the process, you need to get some items close by. Visit an auto store and get the following items.

  • Can of refrigerant
  • Thermometer
  • Hose connector (if the refrigerant doesn’t come with any).

If you want to get everything needed to recharge your car AC and don’t want to look for it one after the other, get a car AC recharge kit. It contains everything you need to recharge your car AC.

Getting your tools and gears close by before proceeding with a repair job will save you some precious minutes.

You’ll need to find a good workspace to carry out the AC recharge properly. A driveway, street parking, or garage floor will be okay. Check your local laws to avoid violations if you intend to do the job on-street parking or driveway.

Here’s How To Recharge Car AC

Note: Always put on your safety glasses when doing work under the hood. Do not allow the refrigerant to touch your skin. Read and follow all instructions on the AC recharge kit.

how to recharge car ac with gauges

Step 1: Switch on the AC

Start the car and switch on the air conditioning system to high or max.

Step 2: Check if the AC clutch is engaging

An AC clutch is attached to the AC compressor, which connects to the engine via a drive belt. The compressor plays a significant role in converting the refrigerant from gaseous to liquid form.

The AC clutch engages when the AC is on high or max settings. Locate the compressor pulley and find out if the clutch is engaging.

If the AC clutch is engaging and it’s still slightly cooling the cabin, you need to recharge the system. However, you still need to test the pressure.

Suppose the AC clutch is not engaging, you likely have electrical issues, a failed AC clutch, or too low refrigerant in the system. Either way, proceed with the pressure testing. After that, add refrigerant to determine why the clutch is not engaging.

Step 3: Test the AC pressure

Switch off the vehicle and locate the low-pressure AC line. Two lines connect to the compressor – the low and high-pressure lines.

The low-pressure line is located on the passenger’s side in the engine bay with a grey or black cap. It is the only fittings that will size the refrigerant hose connector. Test the pressure on the low-pressure line before proceeding to the next step.

Step 4: Connect the recharge hose to the service port

Place the quick connect fitting – found on the recharge hose – on the service port and push it down gently.  You’ll hear a click, which indicates it has snapped in properly.

Be cautious this time. Do not pull the trigger as it will release the refrigerant into the atmosphere.

Step 5: Turn on the vehicle again and monitor the gauge

Turn on the car and switch the AC to the max or highest settings. Get in front of the car and watch when the compressor will engage. Once the compressor engages, watch the gauge.

If it reads below 40 PSI, it means the refrigerant is low. The required PSI should be around 40. You wouldn’t want it to get below 40 PSI.

Step 6: Connect the recharge hose to the refrigerant can

Thread the recharge hose on the refrigerant can. This will allow you to inject the refrigerant into the AC system. Once you thread the can onto the hose, depress the trigger and hold it for 5-10 minutes to inject the refrigerant into the AC system.

After 5-10 minutes, release the pressure gauge to ensure you’re not overcharging the system. Repeat this process until you have 40 PSI. It must not be 40PSI but try as much as possible to get close to that.

Step 7: check the cabin temperature

Determine the cabin temperature using a thermometer. Insert the thermometer on one of the air vents close to the steering wheel to read the air temperature.

A fully charged AC system should blow air as cold as 28 degrees. This can slightly vary depending on the ambient temperature.

If the pressure goes over 40 PSI, consider contacting a technician to discharge the gas a bit. It is referred to as ‘high’ low side temperature. An overcharged system or a faulty compressor can cause A ‘high’ low side temperature.

This is where technical know-how comes in. You may conduct an expert HVAC technician to diagnose the system. Here’s where you can compare DIY AC recharge vs. professional.

You have successfully recharged your AC system. Pat yourself on the back! This guide is also helpful for those asking how to recharge car AC after compressor replacement.


Can I recharge my car AC myself?

AC refrigerant keeps your car cooling at all times. If it stops blowing cold air as it used to, you likely have a low refrigerant in the system.

Fortunately, you can recharge the AC system yourself as far as your vehicle runs with r134a refrigerant. Of course, I know what’s running through your mind. You’re asking how to recharge AC in car r134a, right? Follow the instructions above religiously.

Can AutoZone help recharge AC?

Recharging the AC system is pretty easy. The instructions on how to recharge the car AC above will serve as a blueprint. However, sometimes you need the help of a mechanic.

Instances like when you overcharge the system. You’ll need to take the vehicle to a mechanic to evacuate the overcharged gas with an AC machine.

If you need help with your AC recharge for any reason, consider AutoZone AC recharge. AutoZone and its HVAC technicians have all the tools, gears, and refrigerants to service your R12 or R134A vehicle.

Does an AC recharge kit work?

Many folks think the AC recharge kit doesn’t work, but they are wrong. These kits work perfectly. The most common cause of low refrigerant is system leak. If you cannot repair this leak and keep recharging the system, you’re throwing money down the drain.

Auto part manufacturers produce these kits to fix low system leaks and recharge the AC. Here’s the thing: taking your car to an auto mechanic to tear apart the AC system components will cost you thousands of dollars.

This same issue may repeat next summer and you start running to a mechanic shop. Instead of doing this, get an AC recharge kit with 45 to 60 dollars and fix the leak.

How long does an AC recharge last?

You should flush and recharge the AC refrigerant whenever it gets low. This helps to keep the air conditioner cold and keeps you and the passengers comfortable at all times.

The air conditioner is not something that always runs. Unless you live in a hot climate environment where you constantly make use of the AC, a recharge should last up to three years. Of course, you can take a proactive maintenance schedule for recharging your AC system.

How long does an AC recharge take?

This depends on who is performing the recharge. It’ll take professionals 30 minutes on average to completely remove the old gas and recharge a new one. Whereas, DIY may take up to 1 hour. 

Does Walmart do AC recharge?

Walmart does not offer AC recharge services. Instead, they offer various AC rechargers, which you can find under their oil and fluids under the automotive section.

You can buy recharging kits from Walmart for around 45-60 dollars to recharge the AC at a nearby service shop. You can search ‘recharge car AC near me’ on Google to get the list of nearby shops that offer AC recharge services within your vicinity.

How much does it cost to recharge a car AC?

The cost of recharging your AC system is pretty affordable when considering that it extends the life of the compressor and keeps you and your passengers comfortable.

The cost of AC recharge depends on several factors, like your car’s make and model and whether you serviced it yourself or contact an expert HVAC technician. However, the average AC recharge cost by a professional is around $150 to $300.

You can choose to go the DIY route to cut costs. You’ll spend around $45-60 to get a good recharge kit and recharge the car yourself.

Final words

We’ve provided sufficient information on how to recharge car AC and also answered some questions integral to master the skill of recharging your car AC. This should enable you to go through the DIY route using the guides above.

Given the process still seems too intricate to go for DIY fixing, contact an HVAC expert. Whichever route you choose, it is your choice.

Kindly read your local law if you chose the DIY route. This is necessary because you won’t want to violate your local laws.

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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