AC System

How To Discharge Car AC At Home?

Mike Cross
Updated Jul 4, 2021

Most cars these days have air conditioners in them, and this is a nice luxury to have because it keeps you cool in the summer. If it is hot outside your window isn’t going to do much good, so having your car AC to rely on is a conviction that most people take for granted.

Sometimes though your cars air conditioning stops working and needs to be worked on or the refrigerant needs replaced. In order to work on the AC or replace the refrigerant, the old refrigerant has to be removed.

In this case, it is called discharging the AC unit. You may be wondering if you can do this yourself at home and if so then how. Well, after reading this article you will know the steps you need to take to discharge your cars AC at home.

How To Discharge Car AC At Home?

What do you need?

Before going into how to discharge a car properly AC, we will provide a list of all the things you will need. The main things you will need are

  • An Air Conditioning Service Machine
  • Refrigerant Purity Tool
  • Supply of HC-134A (if you are recharging your AC as well and not reusing old refrigerant)

The list is fairly short of what you need, but it is important to know how to use the tools properly as well. Proper knowledge of how to use the tools and following proper safety precautions is very important with this process.

Coolant is bad for the environment and you, so it must be stored and disposed of properly after being discharged from your vehicles air conditioning if not being reused.

Steps to Discharge AC

The first thing to do to discharge refrigerant from your cars AC system is to determine if the refrigerant is pure or not. You don’t want to reuse bad refrigerant, and you want to make sure there are no sealers in the refrigerant which might tear up the server machine.

You test the purity of the refrigerant you will use the refrigerant purity tool. To do this, you will first need to locate the low and high-pressure ports. A lot of times there will be a minus symbol on the low port and a plus sign on the high one.

After locating the ports, you will remove the cap of the high-pressure port and connect the purity tester to it. This will pull out a small about of refrigerant and test it. If it is pure, you are good to go. If it is not, then other steps which we will explain in a moment must be taken.

After testing the purity of the refrigerant in the AC unit, you will then connect the air conditioning service machine. The way it is connected is by removing both the high and low-pressure port caps.

Then you will take the red line from the AC service machine and connect it to the high port. After you have the red line connected you will take the blue line and connect it to the low port.

Steps to Discharge AC
Steps to discharge AC?

It is important that you have the lines connected all the way because the machine is going to create a vacuum to pull out the refrigerant.

If the refrigerant was pure, then you can move on to removing it, but if it was not, then you need to add filters into the lines to prevent sealants and other things from going into the server machine. You don’t want things going into the service machine because it can damage it.

Once both lines of the machine are connected, you can turn it on. Notice to see if there are any pressure readings. There should be pressure if there is not then you probably have a leak that will need to be fixed.

Most machines are really simple to operate these days. They are automatic, and you just have to push a button or turn a knob to start it.

Once the machine is started, it will turn on a pump and create a vacuum which will suck the refrigerant into the reservoir tank on the machine. If the coolant was pure, then you can reuse it, but if it was not pure, then it will need to be disposed of properly.

After the machine is done pulling coolant out of the cars AC the pressure will have reached zero. That is how you can know if the AC is fully discharged.

It really is that simple to discharge your cars AC. Once you are done doing the repairs you needed you can use the server machine to add refrigerant back into the car as well. This makes the process really easy.

What not to do?

So, now that you know the proper steps to take to discharge your cars AC we will cover what not to do. The first thing that you should never do to discharge your cars air conditioning is to disconnect any hoses while there is a refrigerant.

That is because refrigerant is bad for you and the environment. It is actually illegal in most place to remove it improperly. Also, the refrigerant must be disposed of properly.

The next thing you should never do is remove refrigerant on your own if your area has a law that requires you to have an EPA certification to remove it.

Some governments require you to be certified to remove refrigerant from a cars AC. If your area is one of those, then you need to follow the law.


Discharging your car's air-conditioning isn’t as hard as you might think if you have the proper tools. The problem is a lot of times those tools can be hard for an everyday person to get.

This is due some to the fact that a lot of areas require certification to remove refrigerant from a car because they want to protect the environment and make sure it is done right and disposed of properly.

If you can get an air conditioning service machine, a refrigerant purity tool and a supply of HC-134A, then you can easily discharge your cars ac on your own.

You now know that all you have to do is locate the high and low-pressure port, test the purity of the refrigerant, and then connect the server machine and turn it on.

The service machine does all the work creating a vacuum with the pump and pulls all the refrigerant out into a tank. Then you are done and have an empty AC that you can work on or replace with clean refrigerant. It really is that easy to discharge your cars air-conditioning at home.

Mike Cross
Life is too short to drive with stock audio

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One comment on “How To Discharge Car AC At Home?”

  1. Great Coverage. You covered all my mistakes, ... everyone of them. will now be better informed from now on.

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