How to Recharge Your Car’s Air Conditioner

Knowing how to recharge your car’s air conditioner can save you a bundle. Having a vehicle air conditioning recharge performed at a professional dealership or mechanic can cost $150 or more. 

Conversely, recharging the air system in your car sets you back the price of one AC recharge kit, generally around $50 for the refrigerant and dispenser. Best of all, you can complete this easy DIY task in minutes in the parking lot of your favorite auto parts store once you get the knack. Here’s how to give your vehicle an AC recharge. 

Signs You Need a Vehicle AC Recharge

Sometimes, it’s surprisingly hard to tell when you need a vehicle air conditioning recharge, especially if you live somewhere like Phoenix, AZ, and don’t have tinted windows. One hundred ten degrees Fahrenheit is just plain hot, and while your car’s machinery might drop interior digits down to a manageable level, you’ll still sweat. 

However, the most reliable sign that you need to recharge the AC system in your car is when your vents start blowing warm instead of cold. Other signals include: 

• Ice on the frost lines or compressor.
• Losing the AC clutch, so you can no longer hear the change when you switch to the AC function on your dial. 
• Greasy puddles form under your car when parked. 

You can also test the level of coolant you have with the same AC recharge kit you use to recharge the AC system in your car. When you purchase this kit, you’ll notice that it comes with a gauge. Attach this indicator, following the instructions below, to determine your fill level. 

Other Reasons You May Lose AC Other Than Needing an AC Recharge

Needing a vehicle AC recharge is only one reason why your car may lose AC. Other issues can also cause you to blow hot if your vents work at all. You might also consider the following: 

• A car that blows hot air may also have a faulty compressor. A new compressor can cost anywhere from $1,000 to $2,000 on average but varies by make and model. 
• AC that blows cool but not cold can also result from a filthy compressor or air cabin filter. A good cleaning and filter change may do the trick, but this sign can also indicate a worn-out compressor. 
• If the air is cold but barely blows, your filter is likely to blame. Those who live in dusty areas may need to change their air cabin filters more often. 
• If you notice freon leaking, the leak puts undue strain on your car’s AC system. It’s also not good for the environment, as it eats holes in the ozone layer and contributes to rising temperatures, which people are now beginning to feel. It could be a seal or o-ring, or you may need to replace components like your high line. 

Changing your filters is likely something you can DIY. Your cabin air filter is often behind your glove box or in your main engine compartment near the windshield — your owner’s manual will point the way. 

Changing your engine’s air filter should be a part of your car maintenance checklist. It’s not that different from changing the air filter in your house. Simply locate and unfasten the housing, then take out the old filter and drop the new one in after wiping any grime off the casing, just as you would vacuum out the dust bunnies when changing your home air filter. 

What Causes Your Vehicle’s AC to Need a Recharge? 

The refrigerant that cools your car operates as both a liquid and a gas. Over time, some of the gas escapes due to minor cracks in seals and slight parts expansion with changes in temperature. You can also develop more serious leaks in your high or low line, which often require professional attention to repair. 

Crucial Note for Hybrid Drivers Performing an AC Recharge

However, you must use the right class of refrigerant for your vehicle. Failing to use the right class of refrigerant in certain hybrids is particularly dangerous and can cause a fatal electric shock, thanks to incompatible oils and seal conditioners. 

Your vehicle’s owner’s manual should contain this information. It may also be on a sticker under the hood. However, don’t fear — if you can’t locate the information, your local auto parts store can by looking up the year, make and model of your ride in their computer system. 

The Supplies You’ll Need 

Walk right into your local auto parts store with confidence and proceed directly to the desk. Give the representative the year, make and model of your vehicle and tell them you need to recharge the AC system in your car. They’ll return with a bottle of refrigerant with an attached dispenser — a hose, pressure gauge and a line set, or a little circular clip that attaches to the low line of your vehicle. 

You can also buy the containers of refrigerant and the dispenser separately. Doing so makes sense if you own multiple vehicles that regularly require an AC recharge. It keeps a bit of plastic out of landfills and saves money. 

Alternatively, you can consult your car’s owner’s manual or the sticker inside your car’s hood to identify the correct type of refrigerant. Remember, you must get the proper class of refrigerant for your vehicle, so don’t grab any old bottle off the shelf — when in doubt, refer to your manual or ask a store associate. 

Besides your refrigerant and attached dispenser, you should also have the following: 

• Work gloves: A pair of gloves prevents your fingers from frostbite if you accidentally get a bit of refrigerant on them or from burns if you accidentally touch a hot engine component.
• Safety glasses: To prevent accidental splashes that can blind.
• A rag: For wiping up any leaked refrigerant. 

Although it’s unlikely you’ll run into trouble when learning how to recharge your car’s air conditioner, it pays to be prepared. Protecting yourself takes little but can prevent painful injury. 

Locating Your Vehicle’s Low Line 

Your next order of business is to locate your vehicle’s low line. It typically looks like a thin metal pipe that carries refrigerant at low pressure to the evaporator to cool off the car. Manufacturers generally mark it with blue, while marking the high line in red. It’s also larger in diameter than your high line. You can typically see it simply by opening the hood of your car — most manufacturers make it accessible for vehicle AC recharge purposes. 

Your owner’s manual should contain a diagram that illustrates where to find the low line. You can also locate your compressor and condenser, as it will attach to both. However, in most cases, it’s easy to find. Remove the cap and place it somewhere you’re sure not to lose it — it’s relatively tiny and easy to misplace. 

Attaching the Refrigerant to the Low Line 

Perhaps the trickiest aspect when learning how to recharge your car’s air conditioner is attaching the can of refrigerant to the high line. If you don’t attach it correctly, you’ll waste valuable refrigerant, costing you money and harming the planet. Furthermore, the gauge won’t work. 

First, find a flat place to park and apply your parking brake. You’ll need to run the motor while recharging the AC system in your car, and you don’t want to roll. A set of wheel chocks enhances safety when working alone, especially in hilly areas. 

It’s best to perform your vehicle’s air conditioning recharge when the engine is cool. Other components can get quite hot and burn you when your car is fresh off the highway. However, sometimes you simply can’t wait. Fortunately, once you’ve mastered the art of how to recharge your car’s air conditioner, you can quickly and safely perform all the steps, even in less-than-ideal conditions.

When to Start Your Engines

Here’s a pro tip for the newbies. You’ll want your engine running when you perform a vehicle air conditioning recharge. Starting the engine before opening the hood lets you see the belts on the compressor turning, which experts appreciate. However, popping the hood with everything running can seem intimidating at first. It’s okay if you attach the refrigerant before cranking the engine and turning your AC and fan to the highest settings. 

To attach the refrigerant, pull back the line set on the dispenser to clip the bottle to the protruding metal stem on your low line. Test to see that you have attached it correctly by tugging on it — it should adhere to the stem and not detach. Ensure you have established this firm grip before proceeding to the next step.

Manufacturers design the hose and line set on dispensers to fit on the low line, not the high line, preventing you from accidentally attaching your kit to the wrong port. If yours doesn’t readily attach, check to ensure that you have located your low line, not your high line. Another clue is that your high line will be hot if you have been driving. 

Charging Your Air Conditioner 

Here’s the easiest part of the operation — but it may require the greatest mindfulness. Section 608 of the Clean Air Act prohibits knowingly venting refrigerants during the maintenance or repair of an appliance or car. What does this mean to the average Jane or Joe? It means you must take your vehicle to a mechanic if you accidentally overfill, so keep your eyes on that gauge. When it gets just above the center of the green, you’re good to go. 

If you are a 2-person operation, one person can remain in the car as you begin your vehicle AC recharge process. They’ll feel the air beginning to blow cold as you enter the green zone. Otherwise, you must rely on the gauge.  

Occasionally, albeit rarely, you’ll need more than one can of refrigerant to finish the job. If this occurs, keep the dispenser connected to the low line and untwist the old can. Reattach the new can to resume the AC recharge process. Twisting the can slightly from side-to-side during the fill — from 12 pm to 3 pm — dispenses the product smoothly and consistently. 

When you complete recharging the AC system on your car, carefully detach the line set from the stem. Store the excess in a safe location away from sunlight and heat, or follow the instructions for safe disposal below. 

Special Conditions to Note While Charging Your Car’s Air Conditioner

What if you hop back in your ride after performing a vehicle air conditioning recharge and still have problems? Follow the recommendations if any of the following conditions apply. 

1. What If You Notice Dye Along the Line When Doing an AC Recharge? 

Many refrigerants today come with a dye that tells you if you have a leak. These often occur along seals, but not always. What is certain is that noticing dye means you have a leak that usually requires a trip to the mechanic. Even if you have the necessary know-how to replace O-rings and seals, such as between the low line and the compressor, you’ll need special tools to avoid refrigerant release that most DIY mechanics lack. 

2. What If the Refrigerant Will Not Dispense? 

Several things could have gone wrong if the refrigerant doesn’t dispense when refilling. First of all, a vehicle AC recharge can sometimes take several minutes. However, if you still aren’t making progress:

• Check to ensure your engine is running and the AC and fan are on full blast. 
• Check to ensure the dispenser is properly attached to the low line stem. 
• Check to see if your compressor is broken. Otherwise, the computer that controls it may need to be reset. The compressor in many models automatically stops working when refrigerant levels get too low. Many modern cars lack a reset button, necessitating a trip to the mechanic. You could also try disconnecting the battery for at least 15 minutes to reset your systems. After reconnecting it, observe the belts on your compressor to ensure they turn. 

3. What If the Car’s AC Doesn’t Blow Cold? 

If the car’s AC still doesn’t blow cold, the problem likely lies in your compressor or elsewhere in your vehicle’s AC system. Adding more refrigerant is not the answer. Consult a mechanic who can often diagnose the problem using your car’s OBD-II port. 

4. What Happens If You Accidentally Add Too Much Refrigerant? 

Adding too much refrigerant inhibits the process of converting it from a liquid to a gas. As a result, it remains liquid and can damage your compressor and other engine components. You must take your car to a mechanic with specialized equipment to bleed your lines of excess refrigerant to avoid damage.

Disposing of the Empty Freon Containers 

Disposing of empty refrigerant containers is sometimes as easy as returning them to the store for recycling. Not all retailers offer this capability, but simply asking about the option increases the odds they’ll add such services in the future. Otherwise, you can contact your regular waste management provider to inquire about recommended disposal methods. 

You can store leftover refrigerant for later use, keeping it away from heat and flame. You can also contact an EPA-certified reclaimer, although you may have to call around quite a bit to locate one that serves your area for small quantities. 

Recharging Your Car’s Air Conditioner 

It’s relatively simple for even novice DIYers to learn how to recharge your car’s air conditioner and save money at the shop. You can find a far better use for that extra $100 in your wallet. Performing a vehicle air conditioning recharge increases your confidence that you can handle minor repairs without calling a pro. It also keeps you riding cool with your fresh AC recharge.