Your car’s air conditioner is, of course, the system that allows you to adjust the air temperature inside your vehicle. If there comes a point where you have to make repairs to your car’s air conditioning, you’ll have to drain the refrigerant from your A/C in order to make any repairs.
In order to properly drain the refrigerant from your A/C, you’ll need a piece of equipment known as an A/C recovery machine. Depending on what kind of refrigerant your car uses, you may also need a license to legally handle it.
Today, we’ll be walking you through how to drain and recharge the A/C system in your car, and we’ll explain how your car’s A/C works and what the difference is between the various types of refrigerants that are available.
How Does My Car’s A/C System Work?
Before we get into how to drain your car’s A/C system, let’s take a quick second to go over how the system works. If you’re draining your A/C system to try and make a repair, knowing how your system operates might make this repair a bit easier.
The first major component of your A/C system is the compressor. The compressor is essentially a pump that pressurizes the refrigerant and moves it throughout the system. When the refrigerant enters the compressor, it increases in pressure but also in temperature.
To do its job, the refrigerant needs to be at a relatively low temperature in order to absorb heat from the engine. After the refrigerant leaves the compressor, it enters the condenser, which lowers the temperature of the refrigerant but retains its pressure.
Once the refrigerant has been cooled by the condenser, it enters the receiver. The receiver is a chamber filled with a bunch of filters and dessicants that remove water and other impurities from the refrigerant. It’s important that there is absolutely no water in the refrigerant, otherwise it can end up freezing inside the A/C system and damaging it.
After leaving the receiver, the refrigerant hits the expansion valve. The expansion valve does two things; it greatly lowers the pressure of the refrigerant, turning it from a liquid to a gas, and it cools the refrigerant even further.
Finally, once the refrigerant is in a cold, low-pressure state, it enters the evaporator. As the refrigerant flows through the evaporator lines, it absorbs all the heat in the surrounding air. A fan blows over the evaporator and sends this chilled air into the passenger compartment.
Finally, when the refrigerant has finished passing through the evaporator, it is in a hot, low-pressure state, and is ready to enter the compressor again.
What Type of Refrigerant Does My Car Need?
You might think that all cars use the same kind of refrigerant, and up until about 25 years ago you would have been right. However, these days there are a few different types of refrigerants for car A/C systems.
If you’re unsure of what the difference is between these types, let’s clarify that now.
Often, you’ll see people refer to A/C system refrigerant as “Freon”, although nowadays this is not strictly accurate. Freon is actually a trademarked name, and is only found on refrigerants that contain chlorofluorocarbons (CFCs).
R12 refrigerant is the only refrigerant on this list that actually contains Freon. As of 1994, Freon has been banned from all new cars sold in North America because it was found to have serious negative effects on the planet’s ozone layer.
Older cars that were made to take R12 refrigerant are still allowed on the road today, and R12 is still available for such vehicles. However, it’s possible to convert an older car to run on newer types of refrigerant, which can make your A/C system more environmentally friendly as well as more efficient.
As of right now, R134a is the most commonly-used type of refrigerant in car A/C systems. Compared to R12, R134a is more environmentally friendly and more efficient.
However, it’s still not the perfect refrigerant to use. While it is better for the environment than R12 (or rather, not as bad for it), it’s still not very good; if R134a gets into the atmosphere, it can have a greenhouse gas effect. That’s why R134a is starting to be phased out in favor of R1234yf.
R1234yf is the newest variety of refrigerant present in modern cars. It’s pretty much the same as R134a in terms of performance, but the big difference is that R1234yf breaks down much more quickly in the atmosphere. As such, it contributes far less to the greenhouse effect.
How to Drain the Refrigerant From Your A/C
Before you begin the process of draining the old refrigerant from your car, first make sure that you have an A/C recovery machine on hand. You won’t be able to remove the refrigerant without one, so the importance of this equipment can’t be overstated.
In addition, you should make sure that you’re actually qualified to remove your car’s refrigerant. If you have an older vehicle that still uses R12 refrigerant, you can’t legally drain your refrigerant unless you have a license to do so. If your car uses either of the other types of refrigerant, however, you can legally do this yourself.
Assuming you have the right equipment and the right qualifications, here’s how to properly drain the refrigerant from your car’s A/C:
- There are two refrigerant lines on the back of the compressor, one with low pressure and one with high pressure. Each line has a service port that you will attach the recovery machine to. The low-pressure line is the thicker one, which the high-pressure line is the thinner one. Once you’ve found these ports, attach the corresponding hoses of the recovery machine to them.
- Start the machine, and it will automatically begin pulling the old refrigerant from the system. It will stop automatically once the system is empty.
- Disconnect the machine from the A/C system, making sure to shut off the valves on the machine before you do so (if applicable).
How to Recharge Your Car’s A/C
Once you’ve removed the refrigerant from your car, you’ll obviously need to add some more before your A/C system can run again. Here’s how to go about doing this:
- Turn on your car and turn the A/C to its maximum setting. If you’ve totally drained the system, the compressor won’t turn, as there needs to be enough refrigerant in the system to begin with for the compressor to work. Rest assured, if the compressor doesn’t turn when you start the car, this is normal.
- Locate the low-pressure service port on the A/C system.
- Grab your fresh can of refrigerant, and attach it to the low-pressure port using the recharge hose it came with. To do so, just push the fitting for the recharge hose on top of the port until you hear it click into place.
- With the can of refrigerant securely attached to the service port, pull the trigger on the recharge hose for about 5-10 seconds to fill the system. You don’t want to overcharge the system, so fill it until you get an internal pressure reading of about 40 psi.
How Often Should I Recharge My A/C System?
Unlike other automotive components that should be inspected and replaced periodically, A/C systems will pretty much always work as long as they’re maintained correctly. In short, you don’t have to recharge your A/C system unless it’s not working as well as it normally does.
Does Adding More Refrigerant Make My A/C Colder?
Yes, but only up to a certain point. A/C systems are designed to operate at a very specific charge capacity, and overfilling your A/C system with refrigerant will actually make it less effective.
This is because it’s not about the amount of refrigerant in the system that determines how well it works; rather, it’s about the level of pressure within the system. Overfilling your A/C system will overpressurize it, which makes it much harder for the liquid refrigerant to change into a gas when it has to.
Why Is My Car’s A/C Not Working?
It’s important to have a working A/C in your car, especially if you live somewhere that gets really hot in the summer. In this instance, having a working A/C system is not only a quality of life feature, but also an important safety feature; it can get dangerously hot in an enclosed car if there’s not air conditioning.
As for why your A/C might stop working, these are the most common reasons:
- The compressor is faulty
- There is a refrigerant leak
- The condenser is clogged or broken
- There is an electrical issue