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So your air conditioning (AC) is blowing hotter air than a politician hoping for reelection Bummer! Rolling the windows down only goes so far, and sitting in a stagnant olfactory pool of under-thigh sweat and oil-rich exhaust fumes is a recipe for an uncomfortable and nauseating ride.
Contrary to the perceived belief that AC injects icy air into the cabin, an AC system creates the feeling of cool air by making the hot air less hot. It removes heat rather than adds cold. This is accomplished with a circulating system that includes both a compressor and a condenser and relies on refrigerant, which absorbs heat. The most frequent reason an AC system goes warm is a low level of that refrigerant.
Luckily, that’s also the easiest thing to fix. To get you back to feeling icy and cool in the summer’s heat, The Drive’s informational team is here to show you exactly what you need, what to do, and how to do it.
Now, let’s follow these steps to learn how to recharge car AC.
Recharging Car AC Basics
Estimated Time Needed: Half-hour
Skill Level: Beginner
Vehicle System: AC System
How Does Car AC Work?
There are seven main components of a car’s AC system. The system uses a closed-loop format and runs refrigerant throughout. Here’s the role of each piece of the puzzle:
- Compressor: Powered by a belt-drive, the compressor pulls in cool gas refrigerant, turns the refrigerant hot, and pumps the refrigerant through the AC system loop. From the compressor, the pressurized refrigerant goes through the high-pressure tubing into the condenser.
- Condenser: The condenser turns the gas refrigerant into a liquid refrigerant. The air passing through the condenser helps cool down the hot refrigerant and remove heat from the air conditioning. This cools the refrigerant into a liquid. From the condenser, the refrigerant moves to the receiver/dryer.
- Receiver/dryer: A canister or reservoir that helps remove moisture from the AC system. If water gets into the system, it could freeze and damage an AC system’s components.
- Thermal expansion valve/orifice tube: Between the dryer and evaporator is a valve that restricts the flow of the liquid refrigerant and lowers its temperature. This allows the refrigerant to expand and pressure to go down.
- Evaporator: The evaporator is typically located under the dash inside the car. Cool low-pressure refrigerant enters the evaporator and turns into a gas as it absorbs heat from within the cabin.
- Accumulator: An accumulator is typically located between the evaporator and the condenser. Similar to a receiver/dryer, it acts as a system filter and helps eliminate moisture, whether that be water or refrigerant.
- Refrigerant: The refrigerant that goes in automotive AC systems is called R134a, or 1,1,1,2-tetrafluoroethane. It is a chemical gas that has a boiling point of 15 degrees Fahrenheit below zero. This boiling point rises, however, under pressure and condenses into a liquid.
Car AC Safety
Working on your car can be dangerous and messy, so here’s exactly what you’ll need to ensure you don’t die, get maimed, or lose a finger.
- Safety Glasses
- Mechanic Gloves
Additionally, working with cans of compressed air presents its own set of safety concerns. Never leave the pressurized can in direct heat or on top of a hot engine block. In extremely rare cases, the can could be heated to the point the compressed air explodes.
NOTE: Spraying refrigerant into the air is ILLEGAL.
Everything You’ll Need To Recharge Your AC
Take a quick trip to the local auto parts store, and you’ll be ready to go.
- Can of refrigerant
- Hose connector, if not included with refrigerant.
Or if you don't want to bother with a bunch of parts, and like to have everything that you need nicely organized in one place, then you can use an AC Recharge Kit .
Organizing your tools and gear so that everything that you need to recharge your AC is easily reachable, will save precious minutes waiting for your handy-dandy child or four-legged helper to bring you the sandpaper or blowtorch. (You won't need a blowtorch for this job. Please don’t have your kid hand you a blowtorch—Ed.)
You’ll also need a flat workspace in order to recharge your AC properly, such as a garage floor, driveway, or street parking. Check your local laws to make sure you’re not violating any codes when using the street because we aren’t getting your ride out of the clink.
Here’s How To Recharge Car AC
Anybody who can follow instructions can recharge car AC. Get your glasses and gloves, grab the refrigerant and attachment hose, and let’s get chilly!
- Turn the car on, make sure it’s in park, and put the parking brake on.
- Turn the AC to its coldest setting, crank the fan to its highest setting, and hit the button to recirculate the air.
- Pop the hood, find the AC low-pressure service port between the compressor and the evaporator, and remove the plastic cap. If you are unable to find the service port, A/C Pro offers a handy online port finder. A secondary method is to use the connector piece from the refrigerant hose, as it will only fit on the low-pressure port.
- With the attachment hose disconnected from the can of refrigerant, connect the hose to the low-pressure point.
- With the compressor cycling, look at the included gauge and rotate the temperature dial to the current temperature.
- If the pressure reading is in the red portion of the gauge, do not recharge. This is a sign of a bigger problem, possibly a faulty or malfunctioning compressor.
- If the PSI reads lower than the designated “full” area on the gauge, it needs more refrigerant.
- Detach the hose from the service port.
- Remove the safety tab from the can of refrigerant, shake the can, and reattach the gauge and hose to the can.
- Connect the hose to the low-pressure service port and use the trigger to begin recharging the system with refrigerant. Rotate the can up and down to maintain good refrigerant flow.
- Use the built-in gauge to determine when the system is full. Do not overcharge.
- Remove the connector from the port and recycle any empty cans according to local recycling laws.
You did it, congrats!
Get Help With Recharging Car AC From a Mechanic On JustAnswer
The Drive recognizes that while our How-To guides are detailed and easily followed, a rusty bolt, an engine component not in the correct position, or oil leaking everywhere can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs.
So if you have a question or are stuck, click here and talk to a mechanic near you.
Pro Tips to Recharge Car AC
Over the years, The Drive’s editors have worked on dozens of vehicles and logged hundreds of hours wrenching under fluorescent garage lights. During our experiences, we’ve picked up a few tricks and noted the important things. Here’s what we learned in our times recharging car AC.
- Do not overcharge the system with too much refrigerant. This could damage the system’s internal components.
- If a system gets cold after recharging but reverts to pumping out warm air, there might be a leak in the system. An easy way to detect that is by using a refrigerant leak detector.
Related Post:Best RV Air Conditioners
How Often Do You Need To Recharge Car AC?
Refrigerant slowly leaks out of a car’s AC system, but there isn’t a schedule to follow for AC maintenance. If you own one of the AC pressure gauges, simply use that to check the system whenever the AC seems to be losing its cool.
How Much Does It Cost To Recharge Car AC?
A basic can of generic refrigerant costs less than $10. A can that includes a hose and a gauge will likely cost roughly $40-50.
Life Hacks To Recharge Car AC
Because you may not have access to the right tools, or have a friend you can bum a wrench off of, we also compiled our best hacks to make your life easier and drain your pocket less.
- If you have access to a chain auto parts store such as O’Reilly’s, Autozone, or Advanced Auto Parts, you don’t need to buy the refrigerant with the build-in hose. These stores will lend you the tool to use with the can of refrigerant you just purchased.
Featured Car AC Products
Got a question? Got a pro tip? Send us a note: firstname.lastname@example.org
How much AC recharge do I need for my car? ›
Most cars hold between 28 and 32 ounces of refrigerant (or about 2—3 12oz cans), however larger vehicles and those with rear A/C will likely hold more. Check your vehicle manual for the system capacity for your specific vehicle.What happens if you put too much AC recharge in your car? ›
Having too much refrigerant in your AC can damage the compressor. This can happen because the excess refrigerant will likely collect inside the compressor and cause subcooling, wherein temperatures are below normal. Furthermore, the extra refrigerant can flood the compressor and damage its mechanical parts.Why won t my air conditioner take refrigerant? ›
If you see a very high pressure on the high side gauge and very low pressure on the low side gauge, there's a Freon blockage. Start by checking the expansion valve or orifice tube. You'll likely need to clean or replace it. If the pressure differential is 150 psi or more, you can recharge the Freon.How do I know if my car AC just needs to be recharged? ›
- Your car is blowing warm or hot air instead of cold. ...
- Your car is visibly leaking refrigerant. ...
- The A/C clutch is not engaging. ...
- There's a weird smell coming from your vents.
- Uneven Pressure Levels. You might have trouble telling if you have varying pressure levels on your own. ...
- Frost Layers. ...
- No Air Flow. ...
- Unusual Noises. ...
- Weak Cooling. ...
- Increased Bills. ...
- Shutting Down Completely.
It could be an electrical failure in the circuit during charging, overheating vehicle, or maybe the coolant is just low.How long does it take for AC to get cold after recharge in car? ›
Refrigerant can leak slowly from your car's air conditioning system over time, but recharging the system so it once again blows cold air is an easy DIY task and takes just about 15 minutes.Will my A c compressor not come on if I have to much refrigerant? ›
Refrigerant Levels Have To Be Right
If your system senses the incorrect amount of refrigerant, it will trigger either the high or low-pressure switches and result in your AC compressor not turning on.
If your central AC is not blowing cold air, the refrigerant may be the problem. The unit could be running low and need additional refrigerant added. The most likely cause of this is a leak. A leak not only keeps the AC unit from cooling properly, but also it can cause other issues within the home.Do you run the car when adding freon? ›
Step 3: Hooking Up the Freon
Now start the car and turn the AC or climate control to high and the fan on high. Make sure the temperature control is at full cold or set it to the lowest temp you can if it has numbers. Now we are ready to charge the system.
How long does AC recharge last in car? ›
Most AC systems in a car last for around 3-4 years, or five years, with recharging freon. Freon is a refrigerant recirculated in a closed system in your car to cool the interior.Is it OK to run car AC without freon? ›
Although an air conditioner can still function at lessened cooling power after it loses refrigerant, it will start to sustain serious damage that will eventually lead to larger repair needs and possibly a full system breakdown.How do I know if my car AC has enough Freon? ›
Listen For The A/C Clutch to Engage
When you turn on your vehicle's air conditioner, if you listen closely, you will hear a 'click' which signifies the clutch engaging. If the Freon levels are too low, the clutch will fail to engage which means there's not enough refrigerant for the compressor to pressurize.
An A/C System that is working properly should have 150 PSI on the high side and 30 PSI on the low side.Can AutoZone recharge my AC? ›
When it's time for an AC recharge, turn to AutoZone. We carry R134a refrigerant, PAG46 oil, AC stop leak, AC system cleaner, and more.How long does a full AC recharge take? ›
Car Air Conditioning recharge process takes about 45-60 minutes to completely remove the old gas and refill with fresh refrigerant.Will an overcharged AC still cool? ›
Experts say that excess refrigerant in an overcharged residential or commercial AC unit will collect inside the compressor and cause subcooling, resulting in extremely cold temperatures that can reach sub-zero levels, Air conditioners aren't designed to handle sub-zero temperatures.
- Odd Sounds. You might hear some strange noises when you flip on your vehicle's air conditioner and if you do, it's probably the compressor. ...
- Hot Air. The whole point of turning on your vehicle's AC is to get cold air to come through the vents. ...
- Fluid Leaks. ...
- Stuck Clutch.
“How often should I be adding refrigerant to my A/C?” is a question we get a lot here at Needham Oil Complete Heating & Cooling…and the answer is a simple one: Never.Why is my car AC blowing hot air after recharge? ›
A car A/C blowing hot air is often the result of a refrigerant leak. Refrigerant is a liquid that circulates through your car's A/C system, expanding and contracting as it removes heat and humidity from the cabin.
Can AC lose Freon without a leak? ›
This is, unfortunately, a dangerous misconception. Because, if you're losing refrigerant from your system, it actually means you have a leak.How do I reset my AC compressor? ›
- Power down your AC. Start at your circuit breaker panel and flip the breaker that powers your AC. ...
- Find the button. Most air conditioning units are equipped with a reset button. ...
- Hold down the reset button for 3 to 5 seconds and then release.
- Restore power to your AC.
Common Reasons AC Doesn't Run Cold
The most common causes of broken air conditioning leaks or compression issues. If you are feeling cool — but not cold — air, the issue could be a clogged filter, a problem with the cooling fan, signs of radiator trouble, or it could simply mean it's time to recharge your AC.
If your ac is still not cooling there is one more thing you need to do. This is very important.... TURN IT OFF and call your HVAC service provider to assist you. We always tell our customers to turn off an ac that is not cooling properly.How do I know if my AC compressor is low on freon? ›
- It takes a long time for your home to cool off. ...
- Vents are not blowing cool air. ...
- The temperature you set is never reached. ...
- Your electric bill is higher than normal. ...
- Ice on refrigerant lines. ...
- Water leaking around heater. ...
- Hissing or bubbling noise.
If the refrigeration circuit seems to be working (refrigerant in the system, compressor running and building pressure), but there is still no cooling, the problem might be an obstruction in the orifice tube (located in the high-pressure hose between the condenser in the front of the radiator, and the evaporator located ...Do you add freon to high side or low side? ›
Every auto air conditioning system has two service ports: one on the high pressure and one on the low pressure side. When recharging with AC Avalanche refrigerant, for safety, you will charge through the low side service port. Never charge through the high side port.How long does Freon last in a car without a leak? ›
You're safe to drive without checking the Freon for at least five years—or until you notice a problem (like no cool air). If you need Freon more frequently— like if you're not able to cool down your vehicle even if the refrigerant was recently topped up—then you may have a leak.Can AC recharge damage your car? ›
This process can take many years -- but, eventually, every vehicle will need its A/C system recharged. When you use a DIY canister to add more refrigerant, you can't be sure how much is remaining in the system! This can lead to overcharging the system, which can cause significant damage.Can you overfill a car AC system? ›
Overcharging the unit can cause permanent failure of the compressor, which is the pump for the refrigerant. Replacing the compressor can actually cost more than replacing the entire outdoor unit.
How long does it take for AC recharge to work in car? ›
Has your car's A/C system lost its cool? Refrigerant can leak slowly from your car's air conditioning system over time, but recharging the system so it once again blows cold air is an easy DIY task and takes just about 15 minutes.How long does a recharged car AC last? ›
So, how long does an AC recharge last? Your air conditioning is not something that runs constantly, so unless you live in a very hot climate, you can usually expect a recharge to last at least three years.Will overcharged AC not cool? ›
The Consequences of an Overcharged Air Conditioner
One major problem is that when there's too much refrigerant, it won't be able to properly switch between gaseous and liquid state, and more of it will remain in liquid state. This will harm the system's efficiency and affect cooling in the house.
Your A/C is Blowing Warm Air
One of the most obvious symptoms of low Freon levels is if your air conditioner is blowing warm or room temperature air. As we discussed, the air conditioning system in your vehicle operates by circulating this pressurized refrigerant.
Extreme cold. Experts say that excess refrigerant in an overcharged residential or commercial AC unit will collect inside the compressor and cause subcooling, resulting in extremely cold temperatures that can reach sub-zero levels, Air conditioners aren't designed to handle sub-zero temperatures.