So there I was...traveling home to Northern California after spending the week working on our rental property in Spokane, Washington. Driving south on I-5, I'd just crossed the Oregon-California border and come down into Redding when it started to warm up. My 6 year old dog, Soni, started panting when I reached over to turn on the air conditioner in my recently purchased 2002 Subaru Outback. Then it happened. With the controls set to "max cool" I was surprised by a steady blast of warm air. After several minutes waiting and hoping for relief, I resigned to cracking the windows and suffered through the 85 MPH howl for the next 3 hours. Soni was grateful for the breeze but I was plagued by the thought that I might have an expensive problem to deal with. That was it. My future was set. At that moment I knew that I'd have to learn how to recharge my car's air conditioner system. Luckily as you will see, I was pleased to find that the process is rather simple, affordable, and takes little time.

R-12 vs. R-134a

If your car is a 1994 model or newer, charging your car's a/c system is super easy; all you need is a heartbeat, fingers, eyes, and a recharge kit available from any automotive supply store (Schucks, Pep Boys, NAPA, Kragen, etc.). I discuss the recharge kit in Tools Required. All cars manufactured after 1993 use a refrigerant (just like your refrigerator) called R-134a for which a simple recharge kit will suit your needs. If your car was manufactured before or during 1993, it may not be so easy.  Most of these older cars used a refrigerant called R-12 (Freon), an atmosphere depleting chemical, which has been banned from production because of its adverse environmental effects. If your car was manufactured on the cusp of this switch, or if you are unsure about which refrigerant your car requires, you can find reference to your system's refrigerant on a sticker or tag inside the engine compartment. If no sticker exists, call your local dealer to find out.

Because of the scarcity of R-12, I will focus on R-134a in this article. That said, I have a few words for those of you with R-12 systems. If you have an R-12 system, you should seriously consider converting it to R-134a. I have a 1989 BMW with a discharged R-12 system and I've done plenty of research on the subject. The cost of the conversion is similar to the cost of a couple recharges of your old R-12 system and the new system will be more easily serviceable in the future. If the R-12 system has a leak, and you drop $200 to charge the system, it's $200 wasted (and you just nuked the atmosphere a little bit more). Trust me, you're better off spending the $500ish to get the conversion done.


A fully charged air conditioner system should blow cold air for several years. If your charge lasts less than a few years, your system probably has a leak. If you think you have a leak, fret not! You're in luck; there are recharge cans that contain a leak sealer, they are a little bit more expensive but well worth the extra few bucks. As an added precaution, you can buy a fluorescent dye that goes into the system before it's charged to help you identify where your leak is coming from. This is helpful for those of you who are comfortable replacing hoses and components of your system. If your system is leaking and you intend to recharge it, fix it or have it fixed first. Don't waste your money on charging a leaky system.

Dangers (a token list of don'ts) 

R-12 and R-134a are not compatible. Do not put R-134a into a R-12 system ever. Recharge cans are filled with chemicals under extreme pressure. Do not heat them or dispose of them in a fire. Always wear gloves when handling recharge chemicals. Wear eye protection too. Don't let your kids, or the neighbor's kids (no matter how bratty they may be) play with the can. Don't keep a can in your car; if you have a can in your car and it gets hot enough to rupture, you're in for some damage at the very least. And as always, read all the labels before you proceed. 


Key Concepts

OK, I'm not going to go into all the technical mumbo jumbo that pertains to your car's air conditioner. If you want to learn all about the details of your car's system check out the information at www.autoacsystems.com and  www.familycar.com/classroom. These folks have put together comprehensive, and easy to read, descriptions of every part of the system.

Instead, I'll assume that your system's components work and that you just need to recharge the refrigerant.

As long as all of your system's components are in good working condition, your car's a/c will blow cold air when the refrigerant is filled to the proper pressure level. If the level falls below what is necessary for proper functioning, you wont get cold air. A recharge kit is basically a pressurized can of refrigerant with a valve and a gauge that will let you fill your car's refrigerant to the proper level.

Your car's system has 2 points of connection. You'll only use 1 of these, the other is for discharging the system and should only be accessed by a qualified technician. Don't worry, the two are different sizes and therefore mistaking the high pressure discharge tap for the low pressure charge tap is impossible. The low pressure charge tap is attached to a noticeably larger diameter tube than the high pressure tap. The recharge kit's adapter is specially made to fit only the charging tap; it will not fit the wrong one. On most cars it is indicated by a blue or black dust cap. See photos below.

With dust cap Without dust cap

When you connect a recharge can to your a/c system, the pressure in the can pushes refrigerant into the air conditioner. Depending on how low your system is, you may need multiple cans in order to bring your system up to the necessary level. Refrigerant level is measured by a gauge that comes with the recharge kit; the proper level is usually between 25-45 p.s.i. Don't be intimidated by these #s, the gauge makes it super simple. Your car's system only wants the new refrigerant in gas form, not liquid. Therefore keep the can upright through the entire filling process. This will ensure that none of the refrigerant enters into the system in liquid form. Always check your owner's manual for system capacities before adding or removing any fluids.


Tools Required

Recharging your a/c system's refrigerant is one of the few do-it-yourself projects I know of that doesn't require any real tools. All you need is: gloves, eye protection, working fingers, and a recharge kit (consisting of a can of refrigerant with a valve and a gauge). Below is a picture of the product I use.

Notice the simple color coded gauge. As your system charges, the needle rotates through the colors and will indicate when your system is " filled ".


Recharging Your Car's Air Conditioning System

Step 1

Make sure your car's system is built to handle R-134a. If you're unsure about what type of refrigerant to use, refer to the  R-12 vs. R-134a portion of the Discussion. 

Step 2

Obtain refrigerant. Do this AFTER identifying your system's requirements. You don't want to buy the refrigerant only to find out it isn't what you need.

Step 3

Identify point of charge. Find your car's charge tap and unscrew the cap.

Step 4

Start your car and put your air conditioner on high (max). Let it blow for a couple minutes.

Step 5

Put on your gloves and eye protection.

Step 6

Connect the can of refrigerant to the charge tap. The connector is a "quick connect" adapter designed to work like an air compressor hose chuck (pic 1). The outer sleeve is spring loaded and slides back, when pulled, to enable it to be connected (pic 2, pic 3). Once snugly fitted onto the charge tap, slide the sleeve back to its original position to lock it into place (pic 4).

pic 1   pic 2 pic 3 pic 4

Step 7

Dispense the refrigerant into your car's system, frequently stopping to check the fill gauge for progress. Multiple cans may be necessary to reach your car's adequate fill level. Be patient, this step can take up to 15 minutes per can. If multiple cans are necessary, detach and retain the hose and gauge. Then buy only extra cans. This will save you some bucks and will result in less waste.

Step 8

That's it! Once you've reached the "filled" level indicated by the gauge on your kit, simply disconnect the hose and replace the fill tap's cap. Good Job! Now just be sure to dispose of, or recycle, your recharge can properly.



Automotive air conditioner recharging is super simple. You can save a significant amount of money by taking a few minutes to learn this process and following these 8 easy steps. Believe it or not, most of the projects I write about at Project Sleuth are just as simple. Even though most projects require tools and the competency to use them, they can be broken down to a simple process of linked steps. If this article was helpful to you, check out my other articles and tell your friends and family about the Project Sleuth. If you have questions, comments, or suggestions e-mail The Sleuth at info@projectsleuth.com. Cheers!

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