Car Care

How To Recharge AC on a Car

How To Recharge Car AC

Recharging the AC on a Car Is an Easy Task for Beginner DIYers. Here’s How to Recharge Your Car Air Conditioner at Home.

  • DIY Difficulty Level: Beginner
  • Time Required: 10 minutes
  • Tools & Materials: Car air conditioning recharge kit (about $20-$50 at your local auto parts store or online)

What Is Recharging the Car Air Conditioner?

Before you recharge the AC on a car, it’s important to understand how your AC works and what’s involved with this repair. Your air conditioning system uses a special refrigerant called R134a to remove moisture from the air inside your car and deposit it outside. (This is why sometimes after running your AC you’ll find a puddle of water under your car.) This process cools the air as the moisture is removed, and the blower brings cool air into the cabin. 

Over time, this refrigerant can escape, either through normal evaporation or through leaks that form in your system. Without refrigerant, the AC can no longer move moisture from the inside to the outside of your car. 

Recharging the AC is simply the process of adding more refrigerant to the system. It needs to be at a certain level, not too little, not too much, in order to work properly. A recharge kit is really just a can of R134a refrigerant with a little bit of leak sealer mixed in, a hose that connects it to your car, and a gauge to measure how much of it is in your car. These recharge kits are available for $20 to $50 in any auto parts store and are easy to use. The average cost for an AC recharge at a mechanic is between $123 and $155, so you can save a lot of time and money by doing it yourself.

Is It Safe to Drive with Broken Air Conditioning?

Yes. People have been driving cars without air conditioning for years, from the first cars to hit the road all the way to modern times when the AC stops working. It is perfectly safe to drive without the air conditioner. The only possible safety concern is that your defogger will not work as effectively without the AC running to help it do its job. It will still blow air onto the windshield, which can still help defog it.

All that said, car air conditioner recharge kits make it so easy to do at home that there’s no reason not to at least give it a try. The most common reason for your AC not working properly is a low charge of refrigerant. It’s not the only reason, but it’s certainly worth a try before investigating replacing major components of the AC system.

How Often to Recharge the Car Air Conditioner

Recharging the AC on a car is not a regular maintenance item on your car’s manufacturer recommended maintenance schedule. In theory, the system is sealed, and you should never need to do this. In practice, however, rubber seals dry up and wear out, and refrigerant slowly evaporates over time, leaving not enough left in the system for the air conditioner to work effectively. Other components can fail as well, but attempting a recharge is the first thing you should try, particularly since this is often all it needs to start working again.

What Are Common Symptoms Indicating You Need to Recharge Your Car AC?

  • Cold air no longer comes out of your air conditioning vents
  • Fog doesn’t disappear from your windshield when you switch your climate control to defrost

Keep in Mind

Although recharging the AC on your car is the first thing to try when it stops working, this isn’t a guaranteed fix. The leaks may be too large for the recharge kit to fix, or perhaps your AC compressor has failed. If that is the case, your best bet is to take your car to a professional who is equipped to repair and refill air conditioning systems. Not all mechanics have this equipment. If yours doesn’t, ask them to recommend someone they trust who does. Alternatively, you can use the FIXD app to locate a qualified, trustworthy repair shop in your area.

How It’s Done

Step 1: Buy a Recharge Car Air Conditioning Kit

AC Pro recharge kit

Most auto part stores sell air conditioning recharge kits for about $20 to $50. Make sure the label says “R134a,” which is the correct refrigerant for modern cars. This kit includes a can of refrigerant, plus a hose that connects to the correct port in your car. It should also have a gauge to tell you when you have the correct amount of refrigerant in your car. If there’s too little, it won’t work. If there’s too much, further problems and failures can occur.

Step 2: Start Your Engine and Crank the AC

Air conditioner set to max

To completely recharge your car air conditioner, you need to crank those lines wide open so that the refrigerant will fill everything it needs to fill. Start your engine, set your AC to MAX, and turn the blower all the way to its highest setting. If your vehicle has separate controls for rear AC, do the same for those as well, as shown here.

Step 3: Connect the Kit to the Low Pressure Port

Air conditioner low pressure port

There are two major lines that move refrigerant through your air conditioning system: a low-pressure line, and a high-pressure line. The recharge kit connects to a special port on the low-pressure line for safety. Look up the exact location for your particular car, but generally it’s on a metal pipe that’s easily accessible under the hood. The dust cover for this port often has the letter “L” printed on it. The kit is designed to only connect to the low pressure port. It won’t snap onto the high pressure port, so if you can’t get it to connect, try the other port.

Step 4: Open the Valve and Charge the System

Air conditioner recharge kit

Now that you’re all hooked up, it’s time to tighten the knob or thumbscrew, break the can’s seal, and allow the refrigerant to flow into the car’s air conditioner. During this process, you may notice the AC compressor engage, the engine running slightly faster, and the engine fan turn on. These are all signs that the AC system is filling with refrigerant and beginning to work properly again. (If none of these occur, it’s a sign that your compressor itself may have failed.) 

Air conditioner recharge full

Watch your gauge, and keep charging until the needle is somewhere in the green zone. This means that the system is full, but not too full. Close the valve and remove the hose from the port.

Step 5: Stay Cool

Hop in the car and make sure that cold air is coming out of the vents. If it is, then you’re done! If not, or if you get cold air for a short while but it stops again, find a local mechanic with the knowledge and equipment to work on automotive air conditioning systems. This is one of those jobs that really does require specialized equipment and should be left to a professional.

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Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

Justin Hughes
Recovering autocross and track day enthusiast. Once turned a VW Jetta into a pickup truck. Lives in a van down by the river. Dream car: 2001 Subaru WRC rally car.

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    1. Note; If there is no pressure at all in the system when you attach the gage then you should take to professional. There may be air in the system and needs to be evacuated out after leak has been found and repaired. No refrigerant at all means a bigger leak and your wasting your refrigerant and money. If there is still pressure that means there is less chance of air getting in and you can recharge it.

      1. I would argue that trying this first is less expensive than taking it to a shop immediately, especially if all it needs is a simple recharge. But I agree that if there is still any pressure at all, just low, you have a much better chance of a DIY recharge working.

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