How to Refill Freon in Your Home AC Unit

air conditioner with pressure gauges
  • 1-2 hours
  • Advanced
  • 125-500
What You'll Need
Face mask
Safety glasses
Freon kit
Air Conditioner Unit's user manual
What You'll Need
Face mask
Safety glasses
Freon kit
Air Conditioner Unit's user manual

Your central air conditioner works by performing a complex form of heat transfer with the assistance of a chemical refrigerant. When your refrigerant level runs low, the heat transfer does not take place, and the unit, while remaining functional and blowing air, will not provide cold air. This is a sign that you should be recharging or refilling the air conditioner with freon for AC.

Freon is a non-combustible gas that acts as a refrigerant. It's both a specific product and a common general phrase for a class of hydrocarbon products. These materials are mildly toxic. They can cause mild injuries if they contacted with skin, and serious damage if they're deeply inhaled, so always wear gloves and a mask when working with them.

Before you start, research what kind of refrigerant your unit uses. There are different types, and recharging with the wrong one could cause problems much worse than simply not having a charged AC unit. Don't try this procedure with a window AC unit.

While it is possible to acquire coolant and recharge the unit yourself by purchasing a commercial Freon kit, the rest of the functioning elements of air conditioners can seem dangerous and intimidating to an inexperienced person. If you do not feel comfortable with a project of this magnitude, it’s a good idea to call an air conditioning expert.

DISCLAIMER: We recommend avoiding this type of project and using a professional since it can be hazardous if you're inexperienced. In some areas, it's illegal to use refrigerants or do this kind of work on air conditioning units without the proper license.

Also complicating matters, Freon gas is dangerous when it enters the atmosphere so recovery of the old gas is important. For these reasons, it is necessary to have a professional recharge the air conditioner, but professionals mean spending money.

You can, however, get certified with an EPA Section 609 certification, but you will also need to have the right equipment.

Costs of Freon for AC

AC refill spray bottles

The cost is luckily not extreme, nor should your Freon need to be replaced on a regular basis. Between $100 and $150, you can get a refill which should last for many years. Usually, when a professional refills the Freon, he or she will also check to make sure the system is functioning properly.

However, if the Freon needs to be refilled again in less than three years, you may have a leak within the hoses or valves which will need to be sealed. To get the best price on a Freon refill, check for sales during the cooler months when demand is not as high.

There are some factors to consider that can either raise or lower the cost of a normal recharge. Companies charge by the pound for a Freon replacement, so the size of your unit and the level of your current refrigerant can skew this average up or down.

For a small home, a large AC unit is unnecessary, and the smaller the unit, the less Freon it will need. But, on the other hand, with a large house comes a large air conditioning unit, and this will cost more to refill when it inevitably runs low.

If your technician suspects a Freon leak, your costs will also go up; since the refrigerant is a regulated substance than can be harmful to the atmosphere, the EPA demands that a leak check be performed and any repairs made before the Freon can be refilled.

Refrigerant recharges can also sometimes vary just based on location and time of year, but these factors shouldn’t too dramatically affect the average cost.

When to Add Freon for AC

AC pressure gauges

When you start a new season of air conditioning, you generally hope that the wall air conditioner is going to work just like it did last season. However, there are times when the air conditioner just doesn't seem to be working right. The issue could be Freon.

In theory, freon should last basically forever, since it's just a medium for cooling, not a fuel that gets used up. The only time it should need replacing is when it's been seeping out of your system due to a leak.

One of the first indications that the Freon in your wall air conditioner is starting to fall below acceptable levels is that it will begin to lose its cooling power. The air will not seem to be as cold as it usually is.

Another indication that the Freon is getting low is when the wall air conditioner does not get rid of the humidity like it did previously. You will feel sticky from the heat and the moisture in the air. You may even begin to smell something sweet.

Some of these signs are also indications of other problems within the air conditioner, such as a dirty air filter. When the air filter is clogged, or full of dirt, the air will not get through to the cooling coils.

This is why it is important to regularly clean your air conditioning unit. Spending a few minutes cleaning it will save you a lot of issues in the long run and will make it clearer what the problem is if issues do arise.

Step 1 - Inspect the Unit

Using your air conditioner’s manual, locate the compressor of your unit. It will look like a metal cylinder and have two lines coming off it.

TIP: Before adding the coolant, use this opportunity to inspect the rest of the components and make sure they are clean and working. There are two reasons this is necessary:

1) it may be something other than the refrigerant that is impacting the unit’s performance.

and 2) if fresh refrigerant is added and the unit is powered on while another component isn’t functioning optimally, all kinds of general damage could occur far beyond a coolant or charging issue.

Even when it’s clear something is wrong, the only way to be 100% sure that there is a leak is to do a complete inspection and actually locate a physical leak.

Freon has a slight sweet smell, bordering on the sickly scent of chloroform. It's not flammable, but it's dangerous to breathe in, so make sure your mask is on while you're sniffing around.

Attach a temperature gauge to your valves and wait approximately five minutes to get an accurate reading. Do your research to determine what an adequate reading would be for your unit model, but anything in the 45 degrees Fahrenheit range generally means your coolant levels are sufficient.

If it's above that number, or the number designated in your manual, you may have low coolant levels. Refrigerant doesn't evaporate, so if your AC does not have a sufficient amount, it is because there is a leak.

To locate the source of your Freon leak, you'll need to connect gauges to your AC lines in order to detect any low-pressure issues. If you’re using a Freon kit, the instructions should clearly spell out what gauges and what lines attach where.

If the low side pressure is below 65psi, you most likely have a leak. You can also look for visible signs of leaks along pressure lines and joint connections. Occasionally dyes are added to coolants so that you can visibly see color where a leak is happening. Once your find the source of the leak, you can start the air conditioner repair process.

person carrying freon tank toward AC unit

Step 2 - Purchase Necessary Supplies

The first thing you need to do is find out what type of Freon you’ll need for your air conditioner. If your unit was built prior to 2010, it's likely going to use R-22. To be sure, you can check the unit itself for a label that specifies which type of coolant to add.

The newer systems don’t use refrigerant, so make sure to check your unit before deciding whether a leak is the cause of inefficient cooling.

If you’re certain a leak is the problem, you should purchase a Freon repair kit. These kits are excellent for HVAC beginners and generally come with a reusable injection hose, an AC sealant, and most importantly, a detailed set of instructions. Otherwise, you can choose to buy these items separately in addition to your pressure and temperature gauges.

Step 3 - Turn Off Your System

Turn off your air conditioner and temporarily turn off the circuits that send power to it. If you are committed to doing any internal air conditioner repair, having any electricity running through the system, even if it’s not turned on at that moment is dangerous.

Step 4 - Protect Yourself

Put on your goggles, gloves, and a breathing mask. While a substance like Freon is more toxic to the environment than it is to humans, to humans, it is still important to protect yourself thoroughly.

person changing freon in AC unit

Step 5 - Plug the Service Valve

Locate the service valve inside your Freon kit. It will be the large connector valve found amongst the kit’s other contents. Plug the service valve into a compressor line (one of the lines you located next to the compressor earlier) in your air conditioner unit. Follow the Freon kit instructions to attach the service valve appropriately.

Step 6 - Plug the Tap Valve

freon tank connected to AC unit

Your Freon kit also contains a small valve connector. That valve is called the tap valve. The tap valve must be plugged into the remaining compressor line to your AC compressor.

You will find fittings on top of your air conditioner’s compressor. Follow the instructions in the Freon kit’s manual for the best results or if there is any confusion.

Step 7 - Add Freon

To add Freon to the lines, you need to attach the Freon container to the two valves that you have just installed. Follow the instructions set in your Freon kit to secure the container between the two valves. Basically, the air conditioner will force the Freon into the unit.

Step 8 - Charge Freon

Now that you’ve finished installing new refrigerant to your home AC unit, you need to let the Freon flow into it. To do so, simply turn on the unit and turn it up to the highest setting. This will force Freon into your unit, effectively recharging your air conditioner in the process.

Once the unit is done taking in all of the Freon, turn off the air conditioning unit. Remove the Freon container and the two valves that you installed.

freon tank

Step 9 - Test the System

If you believe you’ve added the proper amount, something that is much easier to determine by using your gauges, let the system circulate for 15-20 minutes as a test run. If all signs indicate that your air conditioner is properly cooling, you can detach your gauges and hoses.

If your AC is still not cooling off, you either need more Freon, or you still have a leak and need to call an HVAC specialist for further investigation.

Cleaning Your AC Unit is Important

Many people will neglect the cleaning of their wall air conditioner because of the hassle of taking it out of the wall housing. However, if this is not done, you might be getting rid of a perfectly good air conditioner. The problems that are associated with the loss of Freon are also similar to those of a dirty AC.

Clean your wall air conditioner every spring to keep from buying replacement parts, expensive equipment, or a brand new air conditioner. If the unit is clean, you have taken good care of it, and it is more than ten years old, then have it checked by a certified technician to replace the Freon.

Set a Maintenance Schedule

A central air conditioner shouldn't need to be recharged every year. However, yearly maintenance and inspection of your unit is a good idea. This will save you from being without air conditioning during the hot summer months if something goes wrong.

The inspection should include a report that details how well the unit is working, how much refrigerant is remaining, and any problem areas that may need attention.

The reality is, an air conditioner unit that's functioning perfectly should never need to be recharged. If the refrigerant level is decreasing, it's because there is a leak somewhere in the system that needs to be repaired.

If a technician suggests just recharging the system, you are leaving yourself open to more problems down the road. If money is an issue, having your unit recharged may help you make it through the summer, but the leak will eventually need to be addressed.

It's best to have the system checked for leaks every few years. This doesn't have to be part of a yearly maintenance schedule, but it's not a bad idea either.

For more on staying cool, check out our pieces on changing AC filters and removing bad odors from your cooling unit.

Refill Freon in Your Home AC Unit FAQ

Can I put Freon in my home air conditioner myself?

Filling an air conditioner with Freon may seem like a simple enough matter but if you are in the U.S., it is illegal for you to handle Freon. For both human health and environmental safety reasons, only EPA-licensed technicians are allowed to handle Freon.

How often should you refill Freon in your home air conditioner?

Unless there is a leak, the Freon in your home AC should last for years before it needs to be refilled. Most AC units need new Freon once every two to five years, on average.

How do I know if my home AC needs Freon?

If your air conditioner needs Freon, you will notice that the air blowing in your home is no longer providing enough cooling. You may even find that the air blowing out from the vents is warm.

Inspect the refrigerant line. When the Freon is low, you may see a buildup of ice on the line and/or hear a hissing noise in the line.

How much does it cost to put Freon in a home AC unit?

Depending on the size of your air conditioner, most homeowners pay around $200 to $400 to have Freon refilled. If you have a larger air conditioner, you may pay $600 or more.

Should you run AC when low on Freon?

The air conditioner can still blow air and sometimes that air may even feel somewhat cooler than warm when the Freon levels are low, but you should not attempt to run the unit while it's low on coolant.

The AC is specifically designed to function with a certain amount of Freon, which provides necessary lubricant, so you can cause damage to the air conditioner if you run it while it doesn't have enough Freon to provide cooling airflow.