Have you noticed that your air conditioning (AC) is not working as well as it used to? Perhaps it is losing power or is not chilling the air as well as it once did? This could be an indication that the AC unit needs recharging. This is the process of adding more of the specialized liquid, called refrigerant, that runs your AC unit.
The simplest option is to have your car checked over by a trained mechanic to get the job done for you. Recharging the AC is considered by some to be a job best left to professionals because it involves hazardous liquids. However, it can cost hundreds of dollars and many car owners do not have the budget for that. If you take extreme care and read up on how to complete the job safely, it is possible for you to do it yourself. It is also vital that you follow the instructions on any AC kit recharge kit that buy.
First, check with your car dealer or a mechanic that your model of vehicle is able to have its AC recharged. Some older vehicles, generally those manufactured prior to 1995, have AC systems that use an R12 refrigerant. This type of refrigerant is not available any more. For these vehicles, the only option is to have the whole AC unit replaced by a mechanic. Modern vehicles use a R134 refrigerant. It is also important to note that there may be a reason for your AC unit needing a recharge. The most likely explanation is that it is leaking. Only a mechanic can identify this and remedy that fault. However, an AC recharge will provide a temporary solution.
If you do decide to go ahead, here are the essential steps.
Step 1: Gather Everything That You Will Need
Get everything that you will need before you start the job. The most essential items are:
- An AC dispenser with a trigger and a low side gauge
- A sufficient quantity of AC refrigerant. It’s usually 12-28 ounces but this information is located under the hood or in the vehicle manual.
- Meat thermometer for checking the temperature after the recharge.
- Safety glasses and gloves – AC refrigerant is highly toxic and very painful if you get it on your skin or in your eyes.
A preferable alternative to buying a dispenser and refrigerant is to buy a special AC kit which has a can of R134 together with a pressure gauge that is built-in. They come with straightforward instructions for the complete novice and are safer for inexperienced people to use.
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Step 2: Prepare the Recharging Kit
Most kits come as separate parts that you will need to put together. Put on your safety gloves and goggles. Then unpack the kit and check that you have a flexible rubber hose, a refrigerant and a pressure gauge. Put these together by following the instructions with the kit. The hose and gauge may already be fixed together. Twist the gauge counter-clockwise until you cannot twist it any more. This will ensure that the pin inside the kit is fully retracted. The pin will later be used to push down and pierce the can of refrigerant but you shouldn’t do this until you are ready to use it.
When you are happy that the piercing pin is completely retracted, put the pressure gauge and the rest of the kit together. The rubber hose needs to be screwed onto the pressure gauge and tightened. Take this opportunity to calibrate the gauge using the calibration dial. You can find out what the outside temperature is by using a phone app or your own thermometer.
Step 3: Test the Pressure
Next, you need to identify the two air conditioning system ports on your car. There will be a low-pressure and high-pressure port and your owner’s manual will indicate where these are. Also, the cap on the high-pressure port is usually labelled with a H for high and the cap on the low-pressure port is labelled with an L for low. Recharging is carried out through the low-pressure port. It is very dangerous to try to recharge an AC system through the high-pressure port so it should not be possible for the pressure gauge to fit on that port. The kit manufacturer should have made it impossible for you to use the wrong port. If you are really struggling to find the low-pressure port, try to find the two aluminum pipes that come out of the metal wall behind the engine. Follow the pipe with the larger-diameter until you get to a port. This should be the low-pressure port.
The area around the ports is often dirty and oily with debris from the environment and the engine. It is vital that this debris does not enter the compressor because it can cause damage which will cost a lot to fix. Therefore, you must clean the outside of the low-pressure port and you must do this before you remove the cap. A rag or paper towel is fine for carrying out this job but be very particular and make sure that you remove every last scrap of dirt. Something as small as a grain of sand can cause a lot of damage to a compressor.
Next, turn the gauge clockwise until you can feel that it has stopped so that you know that the gauge is sealed off and that it is okay to attach it to the low-pressure port. Slide the outside ring towards you with your thumb and forefinger. Once you have placed the inner ring against the port, release it and allow it to snap into place. The latching mechanism will secure the gauge to the port.
For the next step, you need to start the vehicle up and operate the AC. You may want to get someone else to do this whilst you hold the gauge. Let the system run for a few minutes whilst it gets up to pressure. Then make a record of the pressure that the system is operating at. Now turn off the engine.
Step 4: Adding the Refrigerant
Once you have recorded the original pressure, you need to remove the gauge from the low-pressure port again. Be very careful how you do this because you do not want refrigerant to escape into the atmosphere. Turn it counter-clockwise once again to make sure that the piercing pin is completely retracted. Now, fix the gauge onto the can of refrigerant by screwing it on. Make sure that it is screwed on tightly. It is finally time to pierce the can. You do this by turning the gauge clockwise as far as it will go. At some point, you will know that you have pierced the can because it will make a sound as the pressure in the can is released.
It is time to attach the hose to the port once more. Start the engine again and set your AC to its maximum setting. Allow the system a few minutes to warm up. Then you can start to release the refrigerant into the system by turning the gauge counter-clockwise. Gently tip the can to the left and to the right as the refrigerant enters the system. The gauge will indicate when the system is fully charged. If your system had hardly any refrigerant in it, this part of the job will take a little longer.
Step 5: Complete the Job
When the AC system is full, carefully remove the hose and replace the low-pressure port cap straight away to make sure that dirt cannot get in. Don’t discard the kit. It will be useful to use the pressure gauge to periodically check your system using Step 3 above. Also, if your AC needs recharging again, you can just buy the refrigerant instead of buying a whole new kit.
The final step is to check if your efforts have paid off! Use the meat thermometer to check the temperature of the air coming out of the AC. Insert the probe of the thermometer into one of the AC vents. It’s usually recommended that you use the one on the driver’s side and near the steering wheel. You can expect a fully charged system to cool the air to around 28 degrees. Obviously, the temperature of the ambient air will have an effect on this.
Hopefully, this will rectify the situation for a while at least. If the pressure drops again, it is important that you get the AC system looked at by a skilled professional. Repairs of AC systems should only be carried out by trained professionals and is not a job that you should tackle yourself. Also, the refrigerant is highly damaging to the environment so it is not acceptable for your system to be continually leaking.
Sources
- Recharge Your Car’s AC – Thoughtco
- How To Recharge Car’s Air Conditioning – Your Mechanic
