How To Put Freon In Car Air Conditioner? [Step By Step]

The freon level in a car’s AC can leak or get drained off at times. Imagine having to travel in a car with an AC that is low on freon and is not functioning properly. Being too warm or all sweaty while driving can completely ruin the driving experience especially during the summer days. This happens when you run low on refrigerant or freon in your car and the simple fix for this issue is adding more freon. This article discusses how to put freon in car air conditioner so read on!

How Does The Air Conditioning System Of The Car Work?

An air conditioner in a car has An outdoor and Indoor unit that utilises the liquid refrigerant to cool the air. An air conditioner generally has three main parts which are – a condenser, compressor and evaporator. 

The condenser and evaporator are in a way just two radiators connected in a loop. The compressor is situated between the two radiators on one side of the loop. This is a sealed system and is filled with a working fluid named r-134a. R-134 is in a low pressure, gaseous state and the compressor takes the r-134a and compresses it which produces heat. 

After the compression is done it is sent to the condenser. The condenser releases the produced heat outside. The liquid refrigerant now moves to the evaporator. The evaporator is located inside the passenger compartment. Inside the evaporator, the liquid refrigerant is allowed to expand which results in the release of heat and the cooling of the evaporator. A fan is inside the evaporator which directs air to it and then directs the air out through the vents of the car. 

As the working fluid can get very hot and very cold it is necessary to ensure that moisture is kept out of the system. If moisture is there in the system then it could result in the forming of ice in the compressor which would in turn damage it. 

Another thing that could affect the air conditioner is the amount of liquid refrigerant present in the system. The air conditioner won’t be able to work properly if the refrigerant is too little or too much which is why one needs to keep an eye on the cooling capacity of the air conditioner regularly. 

When Should One Recharge The Car’s AC?

Are you noticing that your car’s AC is not as cool as it used to be? Or are you wondering why it is not working normally? Then it may be an indication that it is time for you to add more freon to your car’s AC. 

You can check the level of freon in your AC and see if it is below the normal level. However, this going down in the freon level is not a very normal occurrence. So you may not need to recharge the freon level in your car’s AC in years after recharging it once. 

The most common reason that results in the reduced freon level in your car’s AC system are clogged filters, leakage or even damaged components. These may even cause full damage to the car’s AC system and not just a reduction in the freon level in your car’s AC. In some cases, the old refrigerant needs to be vacuumed out of the system before you start refilling it with a new refrigerant.  

How To Choose The Right Refrigerant For your Car?

Before knowing how to put freon in-car air conditioner, you should know what type of refrigerant you should add to your car. There are only three types of refrigerants that can be added to your car. The right fit refrigerant for your car will depend on your car’s manufacturer. All cars that are made before 1994 use the R-134 refrigerant. Proper freon was banned since then as it is very harmful to the environment. Vehicles made after 1994 uses the R-134a refrigerant that is less flammable and more environment-friendly than R-134. 

How To Put Freon In Car Air Conditioner?

If you have no previous experience in adding freon to your car’s air conditioning system before, then, you should know how to put freon in-car air conditioner properly using the right steps. 

1. Use The Additional Equipment

Before proceeding further into the steps involved in how to put freon in-car air conditioner, you have to make sure that you have worn the safety equipment like a pair of gloves and protective goggles. 

You also must have a refrigerant dispenser to refill your car’s AC system with freon. Some brands also sell refrigerant cans along with dispensers. But you need to pay close attention to its features before buying them. A model may not sometimes 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 use it to 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. 

2. Install The Dispenser

After gathering all the equipment and wearing the protective gloves and goggles, the first step you should take is to attach the refrigerant dispenser to the can. Make sure that the dispenser is firmly in place before you proceed further to eliminate any chances of leakage or injury. 

3. Check If The Compressor Is Functioning Properly

Follow the steps to check if the compressor is functioning properly.

  • Start the engine. 
  • Turn the AC on. 
  • Turn the fan to the maximum.
  • Follow the hose from the low side fill port to a cylindrical device attached to the engine – this is the compressor

  • Locate the pulley on the compressor.
  • Is the centre part of the pulley spinning? If yes, then the compressor is engaged as it should be. In case it is no, you can proceed to add half a can of R-134a. If the compressor still fails to engage, take the vehicle to your mechanic. 
  • Leave the engine running and the A/C on maximum until you are finished with the entire filling process.

4. Locate The Low-pressure Side Refrigerant Fill Port

Pop the hood and proceed to locate the low-pressure side refrigerant fill port. There will be a small plastic lid with an L printed on the top. Unscrew the cap to find the port. 

5. Attach The Dispenser

Follow the below steps quickly

  • Grasp the connector on the end of the hose thusly.
  • Lift the outer sleeve of the connector.
  • Squeeze the trigger for 2 seconds to purge the hose of any air.

  • While still squeezing the trigger and lifting the sleeve, press the connector firmly onto the fill port.
  • Release the outer sleeve of the connector, then the connector itself. It should snap into place on the fill port.
  • Release the trigger.
  • Gently tug on the connector to ensure it is properly seated on the fill port.

Squeezing the trigger will help in keeping a constant flow of refrigerant from coming out of the hose thus helping in purging out any outside air and moisture. This will help in keeping them out of your car’s air conditioning system. 

6. Recharge The System

First, you need to take a pressure reading after determining the minimum and maximum acceptable pressure readings for the current outside air temperature. If the needle in the pressure gauge shows below the minimum acceptable range, you can start filling. 

Steps To follow While Filling the Freon In The AC System

  • Squeeze the trigger for about 5 to 10 seconds by slowly tipping and shaking the can. You should never turn the can upside down. 
  • Wait for about 30 seconds for the pressure to equalize. 
  • You have to measure the pressure reading on the gauge again. You should know that one should only measure the pressure while the compressor is engaged. If the pressure is still too low, keep adding refrigerant in the manner described above.
  • When the pressure is correct, stop filling and wait for a few minutes. 
  • Check the pressure one last time before removing the dispenser hose and replacing the protective cover on the fill port.


You can successfully fill your car’s air conditioning system if you follow the above steps carefully. One tip that you must keep in mind is that you should not add too much freon to your car’s AC system. Hope the article helped you in filling freon to your car’s AC system properly.

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