How To Add Freon To A Car In 5 Easy Steps


Long rides during the summer months can be unbearable if your car’s AC isn’t functioning properly. Nobody likes to be too warm while driving, and failing to keep your vehicle cool can be very frustrating. That’s why knowing how to add freon to a car can be useful if you are on the road regularly and you don’t have the time to go to a mechanic.

In fact, finding a refrigerant you can use to refill your car’s air conditioning system shouldn’t be too difficult since currently there are only two types of refrigerant you can use in a modern car. So, in this article, we are going to show you how to add freon to a car and take you through each step of the process.

How does a car’s air conditioning system work? 

The air conditioning systems most cars have are consist of outdoor and indoor units that turn a refrigerant into liquid and utilize it to create cool air.

The compressor that is located in the outdoor unit of the AC system applies pressure to the refrigerant in order to turn it from a gas into a liquid. Once the refrigerant becomes liquid it is moved to the evaporator coil or the cooling compartment where its temperature is reduced.

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Afterward, the refrigerant returns to its original gaseous state and it is dispersed by a fan that is a part of the system’s indoor unit. Consequently, the entire system cannot function properly if there is too much or too little refrigerant in it, which is why you must check its cooling capabilities on a regular basis.

When to recharge your car’s AC?

In case you start noticing that your car’s AC isn’t cooling the vehicle as efficiently as it used to, you might want to check if the level of refrigerant is below the normal level. However, you should keep in mind that this happens rarely, and you may not have to recharge the AC system even after years of frequent use.

Clogged filters, leakage, or damaged components are the most common reasons why the AC system starts to malfunction. In some cases, the old refrigerant needs to be vacuumed out of the system before you start refilling it with a new refrigerant.

Choosing the right refrigerant for your car 

Only three types of refrigerants can be added to a car, but which one is the right fit for your car depends on when the vehicle was manufactured.

All cars made before 1994 are using the R-134 refrigerant, but actual freon has since been banned because it was harmful to the environment. Vehicles made after 1994 are using the R-134a refrigerant that is less flammable and more environment-friendly than R-134.

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Some car manufacturers have started using the R-134yf in the last several years because it disintegrates in the air quicker than the R-134a refrigerants. The brands like DuPont, Interdynamics, and Johnsen’s produce some of the best and most eco-friendly refrigerants you can find on the market. Opting for the most expensive option isn’t necessarily the best choice because even the least expensive refrigerants can keep your car’s AC system running properly.

Finding the additional equipment

Besides a can refrigerant, you will also need a pair of protective goggles and a refrigerant dispenser in order to refill a car’s AC system with freon.

Some brands sell refrigerant cans together with dispensers, but you should pay close attention to their features, because a model you’re considering may not allow you to measure the pressure in the AC system.

The refrigerant dispenser must be equipped with both a trigger and a pressure gauge so that you can monitor the pressure in the system while refilling the refrigerant. That is why it is important to purchase a refrigerant dispenser that will enable you to go through the entire process safely and effortlessly. You can find more car maintenance tips at this link.

Adding Freon to a car

Gather all the equipment you are going to need to recharge the refrigerant and use eye protection to avoid injury.

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Install the dispenser 

The first step you will need to take is to attach the refrigerant dispenser to the can. This is an intuitive process as you just have to place the can at the bottom of the refrigerant dispenser and then fasten then dispenser to the can.

Make sure that the dispenser is firmly in place before proceeding further to eliminate any chances of leakage or injury.

Check if the compressor is functioning properly  

You will have to establish whether or not the low refrigerant levels are in fact the reason why your car’s AC isn’t functioning at full capacity.

In order to do this, you will have to start your car’s engine, turn the AC on, and set the fan to the maximum. Afterward, you should locate the compressor that is connected to the engine by a hose on the low side fill port.

You should then search for a pulley on the compressor, and check if its middle part is spinning. The compressor is functioning properly if the middle part of the pulley is spinning, but if it is not you should proceed to add approximately half of the refrigerant can to the car’s AC system. If the issue still persists afterward, you should take your vehicle to the mechanic, as this can be a sign of a more complex problem and you shouldn’t attempt to fix it on your own.

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Find the refrigerant fill port 

After you open the car’s hood you will have to find the refrigerant fill port that is located on the left side of the engine bay. The fill port looks like a small metal pipe that has rubber hose at either end.

The refrigerant fill port should be near the part of the engine bay that is called a firewall, and you should just follow the larger of two hoses that protrude from the firewall. Throughout this process, you shouldn’t touch parts of the engine bay or the high-pressure hoses since they can be very hot.

The refrigerant fill port has a plastic lid at the top and you must remove it in order to start refilling the car’s AC system with the refrigerant.

Connect the dispenser to the fill port 

You must stick to the instructions closely while attaching the dispenser to the fill port, and try to complete the entire process as quickly as possible. The first thing you will need to do is get a firm hold of the dispenser’s connector and then lift its outer sleeve.

Squeeze the trigger to remove all traces of air from the hose that connects the dispenser to the fill port and then push the connector to the fill port while still squeezing the trigger and holding the connector’s sleeve.

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Pressing the trigger ensures that an even flow of the refrigerant is coming out of the connector which reduced the chances of air or moisture reaching your car’s AC system.

As soon as you release the sleeve the connector should fall in place, and then proceed to release the trigger. Double-check if the connector is correctly positioned on the fill port before you start recharging the AC system.

Refill the car’s AC with the refrigerant 

The information regarding the maximum and minimum pressure readings for the different air temperatures should be included in the table that comes with the dispenser.

Checking the current air temperature should enable you to determine the pressure range you are targeting. Afterward, you should read the system’s pressure and if the reading is below the targeted range you should start adding the refrigerant to the AC system.

Make sure that the refrigerant can is correctly positioned before pressing the trigger for approximately ten seconds. Let the pressure stabilize for thirty seconds and then check the pressure value that the gauge is showing.

Keep in mind that you should only measure the pressure while the compressor is working, because you may get an inaccurate reading when the compressor is not engaged. Repeat the same process until you reach the pressure range you were targeting.

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Pay close attention to how much refrigerant you are adding to the AC system because you cannot remove it on your own and you will have to take your vehicle to the mechanic.

You should wait for several minutes after you stop adding more refrigerant to the system and then measure the pressure once again. If the last pressure reading shows the values you were targeting, you can proceed to remove the connector from the fill port and put back the protective cover.

If you feel that the can is empty, you can replace it by turning it upside down and holding the trigger for approximately one minute before unscrewing the empty can from the dispenser. You can then attach a new can of the refrigerant to the dispenser by following the same steps we described, even if the connector is still attached to the fill port.

When done, you should switch on your car’s AC and check if its cooling capabilities are back to normal. If everything went right you will not have to check the level of refrigerant in your car’s AC system for the next six months or an entire year.

Frequently Asked Questions about how to add freon to car

How much does it cost to recharge the refrigerant in the car’s AC system? 

Recharging a car’s AC system with fresh refrigerant isn’t expensive and it shouldn’t cost you much more than $30 or $40. Opting for the most expensive refrigerant on the market isn’t necessarily the best option, as even the cheapest refrigerants can keep your car cool for a long period of time.

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What to do if the pressure doesn’t change between two readings? 

The pressure in the AC system isn’t going to rise as soon as you start adding refrigerant, and it may take a while until you can spot a noticeable difference in pressure between two readings.

How to get a compressor to engage? 

Reading the pressure of the AC system isn’t possible if the compressor isn’t engaged. In case the middle part of the pulley that is attached to the compressor isn’t moving when you start the engine, you should try adding half of the refrigerant can.

If the issue persists after you added fresh refrigerant to the system, you must take your car to the mechanic.

Is it possible to add a freon to a car without a pressure gauge?

Technically, yes it is possible to add refrigerant to a car’s AC system without measuring pressure. However, you can easily end up adding too much refrigerant to the system if you don’t read the pressure values, which can cause serious damage to the entire AC system.


Even though adding freon to cars isn’t a highly complicated process, you must still stick to all instructions in order to avoid causing more damage to your car’s AC system. Finding an eco-friendly refrigerant shouldn’t be too hard, but you should also make sure that you have all the equipment you need in order to go through the entire process safely and efficiently.

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Hopefully, this article has helped you recharge your car’s AC system. Leave a comment and share your experiences with us. You can find some of the most common reasons why a car’s AC is blowing hot air at this link, or you can learn what to do when you add too much oil to a car here.

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