Home Diagnosis and TroubleshootingClimate Control and Air Conditioning How To Evacuate A Car AC System – Is This Worth A DIY Fix?

How To Evacuate A Car AC System – Is This Worth A DIY Fix?

by Jordan Harris
How To Evacuate A Car AC System

Among several questions that automobile owners want to know is, how to evacuate a car AC system.  Evacuating a car’s ac system is an extremely important skill. It ensures that the air conditioning is the perfect condition for those long drives on the highway.

However, some automobile owners shy away from doing this themselves. They believe that they are not equipped enough to perform this themselves. The aim of this article is to counter this notion by providing the information needed to maintain your AC system.

This is a relatively easy process and can be performed by anyone as a DIY project. So, how do you evacuate the car’s AC system? Knowing how to evacuate a car AC system is crucial food the proper maintenance and upkeep of your vehicle.

It entails using proper equipment like a vacuum pump, AC recovery unit, and manifold gauges. You need to keep in mind the OEM-recommended steps. It only takes 30 minutes to an hour to complete the entire process.

An AC system in a car helps to cool the air inside your vehicle. It is made up of different parts like an evaporator, compressor, and condenser. The AC system works by circulating the refrigerant in these parts.

Components Of A Car AC System

The air conditioning system of a vehicle is extremely similar to the components of a normal AC used in a house. You have to keep in mind that a room in a house is huge while on the other hand, the area inside the car is relatively less.

how to evacuate a car ac system

Hence, several modifications are made for the AC to fit comfortably without an issue. Understanding this might help you diagnose why doesn’t my AC work in my car. Or, if you experience issues such as the car AC not working, the car AC not blowing out any cold air, or if the AC only works when you’re driving.

The major components used in a car’s AC are as follows.

1. Compressor

The compressor (and its clutch) of an AC unit in a vehicle is known as its heart of it. The compressor is responsible for regulating the pressure of the refrigerant so that it can help transform the vapor refrigerant into a liquid refrigerant.

This liquid refrigerant is what enables the flow of cool air through the condenser. This further makes the whole cabin pleasant and nice.

2. Condenser

We did talk about a car condenser in the last point, but what exactly does it do? Well as the name suggests a car condenser is responsible for controlling the condensing happing in the AC system.

When you want to set the car’s temperature too high or low, the liquid refrigerant sent by the car compressor has to face the convection force that is put by the radiator fan or by a separate fan. This force is what helps control the condensing.

While you’re looking into AC condensers, it might also prove to be a common point of failure. So, it’s worth being acquainted with some of the bad AC condenser symptoms. And if need be, you might also need to budget for the cost to replace the car AC condenser.

3. Expansion Valve

The expansion valve helps in regulating the already extremely high pressure, by sending a low-temperature liquid refrigerant by the condenser. As the name implies, the expansion valve is responsible for controlling the expansion of the refrigerant as well as reducing the pressure.

It is only after that, it is sent from the car AC expansion valve to the evaporator for the procedure to carry on.

4. Evaporator

As talked on the last point the refrigerant has now reached the evaporator. The evaporator is a device that is placed behind the AC vent and it looks exactly like the heat exchanger.

The responsibility of an evaporator is to take the heat from the car and convert it into liquid refrigerant. Now to do this the evaporator changes this into vapor and further on refrigerant. It is because of this step that you can enjoy cooling through a fan inside the passenger’s section.

5. Orifice Tube

The orifice tube is a device that is in the shape of a cone. And it is responsible for providing restrictions on the flow of refrigerant. Basically, it allows the refrigerant to convert high to low-pressure refrigerant mist before it enters the evaporator.

6. Receiver Dryer

The receiver dryer is known as the safety catch as it maintains the safety of the car. When we are using the air conditioner, sometimes liquid starts flowing towards the compressor instead of vapors, which can damage the compressor.

So the receiver dryer is used inserted between the compressor and evaporator to transform the remaining liquid into vapors and then send it for compression.

7. AC Inline Filter

The air conditioning inline filter is another important part of your vehicle’s air conditioning system. This part is usually responsible for trapping wreckage and dirt that enters the car engine bay while driving. After the air passes through this part, your AC system can then give you clean air.

8. AC Refrigerant

As said before in many of the topics above, the refrigerant has a low boiling point and is used by the air conditioning system of your vehicle as a heat-exchanging medium. The refrigerant usually comes in a fluid or liquid form, and hence changing the temperatures becomes extremely easy through it.

At lower temperatures, this refrigerant converts into gaseous form making it extremely easy to cool the cabin of a vehicle. On the other hand, this liquid at high temperatures takes a liquid state to heat up the cabin to your liking.

Cost To Recharge Car Air Conditioning

There is nothing worse than getting ready to go on a road trip on a hot sunny day without a properly functioning AC system in your vehicle. The cost of getting your air conditioning recharged or serviced is not too expensive (relatively speaking), especially when proper servicing and maintenance can extend the life of your compressor.

Alongside that, it also helps your air conditioning system perform optimally season after season.

how to evacuate a car ac system

A professional AC recharge can cost you anywhere around $150 to $300, including the Freon cost, on average depending upon the make and model of your vehicle. You should get your AC serviced every 100,000 miles or so, due to the fact that your refrigerant diminishes over time.

Hence, if you want your vehicle to have an effective air conditioning system, this service should be added to your list of maintenance schedules. You can also save a little bit of money by performing this service as a DIY project.

While recharging your car’s air conditioning, you can expect to pay anywhere around $40 to $60 for an AC recharging kit (make sure you also understand how to charge AC system). Servicing or recharging your AC might sound like a good and cheaper alternative but you need to know what you’re doing before you start working under the hood.

Even though this method might seem extremely convenient than taking the car to the shop, you need to understand what steps are undertaken while serving the AC at a shop vs doing the job by yourself.

Regardless, there are some things that you need to be wary of. For example, not understanding how often does a car AC needs to be recharged. And thus, mistakenly having overcharged the AC with freon.

AC Vacuum Pump

The air conditioning vacuum pump is responsible for removing unwanted air and water vapor from the air conditioning system of your vehicle. The first thing you need to do while repairing your AC system is to remove and recover the refrigerant from the system. This is usually done so that this refrigerant can be reused later.

Once the recovery of the refrigerant is done, you can now proceed to troubleshoot the AC system and repair the part that is malfunctioning. The next step is to make sure that the system is absolutely leak-free. You need to take certain steps to rectify a leak if there is any.

The evacuation process is the next step to service your car’s air conditioning. This is the part where the vacuum pump is used to remove the air and moisture from the AC system. Once this is done the recharging process of the air conditioning can be carried out. Once the whole process is done do a full system checkup.

You can refer to our guide on how to test a car AC compressor, as a good starting point. The latter might also help if you have issues such as a bad AC pressure switch. Or, if you notice any bad AC compressor symptoms (and how to tell if AC compressor is bad), among other AC-related issues with the A/C compressor in your car.

How To Evacuate Car AC System

The first step for servicing the AC system on your vehicle is to evacuate the existing refrigerant from your AC system. Hence here is the answer to the question on everyone’s mind,” how to evacuate the car system on an AC.”

Evacuating or discharging an air conditioning system on a vehicle is a simple process, provided the necessary tools are available to you.


A car’s air conditioning system needs to be evacuated as a part of the routine maintenance when the system needs to be recharged. Different automakers use an array of different components and parts for their air conditioning system.

However, all of these systems perform the same basic function and follow the standard air conditioning design. Hence the understanding for recharging the AC system remains the same. Here is a list of steps you need to follow to evacuate the car AC system.

How To Evacuate A Car AC System, Step 1:

The first thing that you need to do while evacuating or discharging your vehicle’s AC system is to get the proper equipment to do it. You can not stop this process in the middle and continue the next day as it will damage the AC. Hence you need to prepare before you start discharging your AC system.

The things that you would need are protective glasses and gloves. This is to ensure your safety while working on your vehicle.  Alongside that, you would also need different tools like a manifold gauge, vacuum pump, AC recovery unit, and a recovery tank. The manifold gauges help to point to the central connection on your vehicle’s system.

The vacuum pump like the name suggests removes all the from the recovery tank and creates a vacuum. AC recovery unit moves the refrigerant to the recovery tank. You also need to prepare the recovery tank by opening the valves and releasing nitrogen into them.

How To Evacuate A Car AC System, Step 2:

The next step that you have to undertake is to remove the air and moisture from inside the recovery tank. You can do this by attaching a vacuum pump to its blue-colored valve. You can get a vacuum pump on a rental basis as well. Make sure that the recovery tank valves are closed as you do this.

After this is when you need to turn on the vacuum pump while simultaneously opening the blue-colored valve. You need to leave the vacuum pump for approximately an hour. This is so that all the air and moisture can be removed from the recovery tank. Close the recovery tank valve and the vacuum pump once you are done.

Tip- make sure to do this step in the order as is given. Otherwise, you may end up sucking the oil from the vacuum pump into the recovery tank once the vacuum was created.

How To Evacuate A Car AC System, Step 3:

The third step that you need to do is to hook up the manifold gauges. You need to make sure that these gauges are closed before you connect them to your vehicle. You need to check out and make a note of the high-pressure and low-pressure sides under the hood of your vehicle as you do this.

Usually, the high-pressure port is situated between the condenser and the expansion valve. On the other hand, the low-pressure port is on the return line between the compressor and the evaporator. You need to connect the red manifold connector to the high-pressure side. While the blue connector goes on the low-pressure side.

how to evacuate a car ac system

You’d be familiar with this if you’ve been through our guide on AC low side pressure being too high. You do not need to worry about the size difference between the two as the end fittings of these connectors differ from each other. They are also color-coded for your convenience.

Alongside that, you also need to connect the hoses to the recovery unit. You need to connect the yellow manifold connector to the corresponding port on the AC recovery unit or the machine that says in.

Once that is done you need to get another yellow connector and hook one of the ends to the recovery unit that says out. You need to make sure that the other end of this yellow connector is attached to the blue-colored valve of the recovery tank.

How To Evacuate A Car AC System, Step 4:

The fifth step is to get rid of any moisture or any air that might be present in the air conditioning system of your vehicle. Hence what you need to do is to slowly start opening the blue-colored valve on the recovery tank.

You need to keep checking for leaks simultaneously. Once that is done, open the blue liquid valve on the manifold gauge. This will help remove the liquid from the AC system.

Now what you need to do is to open the red vapor valve on the manifold gauge. This step should finish evacuating the car’s AC system. You need to let this evacuation process run for about 30 to 45 minutes, or till the needles on the manifold gauges read zero.

A zero on the manifold gauges is a good sign because it means that your car’s AC system can hold a vacuum. This is proof that there are no leaks in the AC system.

Here is a quick tip. You can leave the manifold gauges hooked up to the vehicle for about 30 minutes to an hour after closing the pressure lines and vacuum pumps. If the reading on the gauges stays the same, then you’re guaranteed a leak-free AC system.

How To Evacuate A Car AC System, Step 5:

Once the AC system is completely evacuated, you need to disconnect the manifold gauge connectors. As soon as the manifold gauges read zero, close the red vapor and blue liquid valves. However, you need to close the inlet valve on the recovery unit first before the outlet valve. Once that is done, turn off the recovery unit completely.

Remember to close the rest of the valves as well as disconnect the different pipes that are connected to the recovery unit. Alongside that, you also need to disconnect the vacuum pump. You also need to replace the black dust caps originally covering the low and high-pressure lines under the hood of your vehicle.

DIY AC Recharge vs Professional

As said before in this article the air conditioning of your vehicle can be extremely important. Alongside a perfectly working AC system, you’d also want your safety and your car’s safety to be in the best condition.

DIY projects can be extremely fun and especially cost-effective. But if you’re new to DIY, this project is not as easy as the others and can cause harm to you or your vehicle. In some cases, it’s worthwhile paying up the oft-high auto air conditioning repair costs. Or if you’re lucky, perhaps that Honda Civic air conditioner recall has you covered.

If something in this system goes wrong it can be more expensive to fix the problem rather than letting a professional recharge your AC unit. You have to remember that handling refrigerant or freon can be extremely difficult.

There is a massive risk of injury, as they can be any contact with the freon or the refrigerant can be extremely painful if came into contact with. Alongside that, releasing freon into the atmosphere is also extremely dangerous and illegal. Hence if you are not 100% sure of what you’re doing, you should always hire a professional.

If you have experience working on your vehicle, then you know how to handle working on your vehicle properly. A professional working on the AC system has the proper equipment and skills to do this without hurting your vehicle. Here is the difference between an AC recharge DIY style vs a professional.

In Conclusion…

As said before, the AC unit on a vehicle is extremely important, especially on hot days. Hence facing an ineffective AC can be really frustrating. Hence, to fix this problem car owners have been asking the question, of how to evacuate a car ac system.

There are several topics have been discussed in this article regarding this topic. We have introduced you to the components of an AC system, how to evacuate it, and the steps you need to take to overcome this problem. Hence this is everything you need to know about the topic, “how to evacuate a car AC system”.

Frequently Asked Questions

Here is a list of all the commonly asked questions relating to the question, “how to evacuate a car AC system”.

How To Recharge Car AC

The first thing you need for recharging your car’s AC is to figure out the temperature of the air. If the temperature of the air blown is 55 degrees or below. Alongside that, different Ac units have different pressure requirements to work at optimal conditions. So make sure that everything is according to the manual that comes with your vehicle. After that what you need to do is find the low-pressure line port. It is usually marked by the letter “L”. The refrigerant is to be added through that line. You also need to hook up the pressure gauge hose to the port in order to check the readings. Proceed with recharging your vehicle, when the pressure gauge starts to read zero.

How Much To Recharge Car AC

As said before in this article, an ineffective AC system is not the ideal situation. Hence you need to take certain measures to get over this problem. One of the things you can do is hire a professional to recharge your car’s Ac system. Now recharging your AC system can sound like an expensive procedure to get for your car, but that is not the case. An AC recharge, if done by a professional, can set you back about $150 to $200. The price usually depends upon the make and model of your vehicle. You should get your AC system recharged every 100,00 miles as it is important for the normal working of your vehicle. You can also recharge the AC system as a DIY project. A DIY recharging kit can cost anywhere between $60 to $80.

How Much Freon Does A Car Hold

Most modern cars have an extremely effective AC system, but it needs to be serviced regularly. Regular services help keep the AC system as good as new. Now if you want to service your AC system you need to have the correct information about the amount of refrigerant your car can actually hold. Most cars can hold up to 20 to 32 ounces of refrigerant. When we talk about larger cars, like an SUV, will need more refrigerant. To know the exact amount of refrigerant your car hold, you need to have a look at the car’s manual. Whenever you decide to change the refrigerant, it is more likely that there is some refrigerant available inside the system. Unfortunately, there is no way to measure the amount of refrigerant that is already present inside the system.

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