How to Recharge Your Car AC: 4 Steps to Follow

Have you ever been driving on a hot afternoon and turned on your air conditioner, only to have warm air blow out? Warm air from an otherwise functioning system typically means the unit must be recharged with new refrigerant. Luckily, you can do this on your own or have it quickly fixed at a local shop. 

Learn how to recharge your car AC in four simple steps with this guide. 

How Does a Car Air Conditioner Work?

A car air conditioner works essentially like the one in your house; it simply cools a much smaller area. The system works quickly and effectively because there is only a limited amount of air in your car. Like any AC system, it relies on a key component: refrigerant. 

Refrigerants are chemicals that can absorb heat. In a system like a car AC unit, they work together with a compressor and condenser to keep your car cool. The refrigerant goes from low pressure to high pressure as it engages in this process. 

The refrigerant starts as a low-pressure liquid. As it flows through the system, it gets compressed into a gas. In this state, it can absorb heat. As the refrigerant absorbs heat, the air around it becomes cooler. The cool air is pumped out of the system and into your car. The refrigerant continues to flow through the system, where it is depressurized and repressurized, removing heat from the air at each step.

If there is insufficient refrigerant in the system, the pressurization and cooling process will not work efficiently. The resulting airflow is too warm.

Why Do You Need to Recharge Your Air Conditioner?

Recharging an air conditioner means changing or refilling the refrigerant in the system. Like other liquids in your car’s system, this one can leak or degrade over time. Under normal circumstances, you may only need to recharge the AC in your car every few years or less. However, a leak in the system may force a recharge sooner. 

Determining whether or not you need an AC recharge is a lot like ascertaining if your car’s oil needs to be changed. If there are no problem indicators (such as performance issues or blinking warning lights), you can keep going until your next scheduled maintenance or mileage milestone. Similarly, refrigerant won’t need to be recharged until you notice issues or your technician tells you it’s time for maintenance. 

Refrigerant pressure is key to the system working properly, so the system needs consistent levels.

What AC Refrigerant Does My Car Need?

Many types of refrigerants exist, but one is standard for modern car AC systems: R-1234yf. This is a hydrocarbon refrigerant (sometimes also known as an HFC). HFCs were developed because, unlike previous iterations of refrigerant chemicals, they do not deplete the ozone in the same ways.

Other HFCs were used in cars for many years. R12 was the most common HFC used in cars until the 1990s when R-134a was developed. R-134a became more popular until the 2010s when R-1234yf became an even more eco-friendly option. Many manufacturers now prefer R-1234yf, and nearly all new light-duty cars are designed to use it. In 2020, it became the standard car refrigerant used in Canada, as R-134a was phased out of use as part of the Ozone-depleting Substances and Halocarbon Alternatives Regulations. 

If you’re not sure which your car uses, you can check for the information in several places. Many manufacturers put labels under the hood that include this information so owners or mechanics can easily find it during maintenance. If your car does not have this sticker, you can find the information by searching an owner’s handbook or a refrigerant manufacturer’s database. 

Of course, you can also take your car (or the make and model information) to an auto repair shop or supply store and ask for professional guidance. If your car is older and uses a refrigerant other than R-1234yf, you’ll have to get it serviced by a professional.

4 Steps for Recharging Your Car AC

Auto parts suppliers sell cans of refrigerant that you can use to do an air conditioner recharge in your car. Once you have the canister you need, follow these steps.

1. Find the Low Side Port

Low side refers to the pressure in the system, not the location. The refrigerant gets inserted into the low-pressure side of the system, not the high-pressure side. Both the low side and the high side ports are attached to the compressor, which is found under the hood of your car. The low side port is the larger tube. In some car models, the port cap is marked with an L to indicate it’s the low side.

If you’re uncertain which tube is correct, a diagram from your owner’s handbook or information from the auto supply store where you bought your refrigerant can help you.

2. Attach the Can of Refrigerant

Once you’ve located the correct port, attach the can of refrigerant. It should come with a hose and a nozzle that fits the port for easy insertion. The cans—and the ports you use to insert the gas—vary depending on which type of refrigerant your car needs, so you won’t accidentally insert the wrong type. 

If it doesn’t fit, you have the wrong can or port.

3. Dispense the Refrigerant

You’ll want to wear proper safety equipment as you dispense the refrigerant. Use gloves and goggles to protect yourself from any splashes. You should also check the temperature around you, as the ambient temperature will affect the pressure of the refrigerant. Most at-home charging cans have a pressure gauge that guides you based on the temperature. Heat increases the pressure of refrigerant, so the correct readings may be slightly higher on a 30-degree day than on a 20-degree one.

Shake the can and begin dispensing the refrigerant according to its directions. You’ll want to keep putting refrigerant into the system until the gauge shows you’ve reached the proper pressure for your set temperature. Be careful not to overfill, as this can cause other issues. 

4. Check For Leaks

To make sure your refrigerant stays in the system and does its job, you’ll want to check for leaks. If your loss of cold air was sudden, the system may have a large leak, which you’ll typically be able to hear. Listen for audible hissing that indicates refrigerant is leaving the AC unit. 

If you don’t hear any leaks, monitor your air conditioner output as you drive over the next few months to be sure the air stays cool.

Other Potential AC Problems 

Systems can’t always be perfectly calibrated for refrigerant amount and pressure with DIY solutions. If you’re still experiencing AC problems after recharging your refrigerant, the system may need further adjusting. 

In this case, you should take your car to a technician. They can use specialized equipment to check for smaller leaks that your at-home methods might not have found. They can do this in two ways: either by adding dye into the refrigerant that can be detected with a black light or using a probe that can detect the presence of the gas in places it shouldn’t be. 

If they find a leak, they’ll repair it so the AC system is a closed unit again. Then, they’ll use a specialized vacuum to suck all the refrigerant out of the system before replacing it. The system should start working properly once the pressure level is corrected. 

Occasionally, the problem won’t be with your refrigerant at all. The technician can diagnose and fix any other mechanical issues, whether that’s a problem with the condenser, the compressor, or something else entirely.

Where Can I Get Help? 

While a car air conditioning recharge is relatively simple, it still takes time and supplies. If you don’t want to handle it yourself, or if you’ve recharged your AC already and are still experiencing issues, your car may need further diagnostics and repairs. 

CARSTAR can help–schedule an appointment at a CARSTAR location near you!