Signs Your AC May Need A Refrigerant (Freon) Charge

Written By Lester Mclaughlin
Updated On

Are you wondering if your air conditioner needs a refrigerant charge?

You’ve come to the right place!

In this Blue National HVAC guide, you’ll learn:

  • Refrigerant’s role in air conditioning systems
  • Signs your AC unit is low on refrigerant
  • The effects of low refrigerant

And much more!

Signs Your AC May Need A Refrigerant (Freon) Charge

So, if you’re looking for answers to your questions about whether your AC unit needs a refrigerant charge, keep reading our detailed guide below to get answers to all of your questions!

What Is The Role Of Refrigerant In Air Conditioners?

All air conditioning systems contain refrigerant, which serves a vital role in cooling your home. Refrigerant is what helps to cool the air that pumps out of the supply vents in your home. Freon, a type of refrigerant, goes through a recurring cycle as it travels through the system. 

Freon, also known as R-22 refrigerant, is no longer used in new air conditioners. As it undergoes a phaseout, R410a, also known by its brand name Puron, is now the most common refrigerant in AC units. However, if you have an older AC unit, it could still use Freon refrigerant as the coolant. 

Whatever type of refrigerant your HVAC unit has, its role is the same. It undergoes various changes in pressure and temperature in the vapor-compression refrigeration cycle to remove heat from your home. 

When the air conditioning refrigerant enters the evaporator coils in the air handling unit (inside your home), the refrigerant is cool and under low pressure. As air blows across the coils, the heat from the air transfers to the refrigerant. This now cool air blows into the various rooms of your home to cool it. 

At the same time, the refrigerant gets hot and it flows from the evaporator coils to the condenser unit outdoors. There, the compressor increases the refrigerant’s pressure and releases its heat to the outdoors. 

If your air conditioning system is performing poorly, perhaps failing to kick out icy-cold air, and instead puffs out tepid or warm air, the unit may need a refrigerant charge. 

Only trained HVAC professionals who are EPA-certified and well-versed in proper safety methods should complete a refrigerant recharge. However, identifying the signs of low refrigerant first will help determine if you need professional assistance. 

What Are The Signs Your AC Is Low On Refrigerant?

Your AC system should not run out of refrigerant unless there is a leak, as it doesn’t get depleted while cycling through the unit. 

The refrigerant is contained in a closed-loop system, meaning it is not open to the outside environment. Imagine a hula-hoop filled with refrigerant; there’s no “end” or opening to the hula-hoop, so it can never “pour” out. 

Now picture a condenser unit, an air handling unit, and a thermal expansion valve connected in-line with the hula-hoop. The compressor inside the condenser pulls the refrigerant through the hula and forces it to constantly flow through each component, exchanging heat and varying in pressure along the way. In real life, the hula-hoop is made up of refrigerant lines and coils. 

This is the basic premise of a closed-loop system and why your AC unit should never lose refrigerant (there’s nowhere to escape, except a leak). 

If your refrigerant is low, you might notice several signs indicating that such a problem occurs. 

Home Takes Much Longer To Cool

When your air conditioning system is low on refrigerant, the air in your home will not cool as fast. You may notice that the vents are kicking out warm air or that it may be much warmer than usual. In this case, calling our HVAC professionals for help is the best course of action. 

Increasing Electric Bills

A lack of refrigerant in your AC unit may cause your electricity bills to skyrocket. This is due to the excess energy it takes to cool your home. 

When the refrigerant is low, the system can’t work at optimal efficiency, which causes the thermostat to trigger the AC unit to run for extended periods and rack up a substantial energy bill. 

Noises From The AC Unit

Although refrigerant leaks are usually silent, larger fissures or holes in the refrigerant line or coils may be audible. If you notice a bubbling or hissing sound originating from the AC unit, call our HVAC pros immediately, as Freon gas and other refrigerants are toxic. We’ll get a handle on the Freon leak as soon as possible. 

What Are The Negative Effects of Low Refrigerant?

Low refrigerant levels come with an abundance of adverse effects. Your air conditioning system will exhibit several signs when the refrigerant is low, and you may notice several adverse side effects if you fail to address the problem. 

Problems With The Evaporator Coil

The evaporator coil in your air conditioning unit is at risk of freezing when the refrigerant is low. How is that possible in the middle of a sweltering summer day? 

Frozen AC Unit

The reason ice forms is from refrigerant gas leaking through holes in the coils themselves. When it leaves the coils, it rapidly expands (which cools it). This rapid cooling is due to the thermodynamic property of adiabatic cooling. 

When refrigerant leaks and cools, it freezes the moisture in the air around coils, forming ice.

However, if you notice ice coating the evaporator coils, don’t try to scrape it off, as you may further damage the coils or cause more refrigerant to leak. Instead, call our HVAC technicians for assistance. 

Damaged Compressor

The compressor in an air conditioning system compresses the refrigerant to a higher pressure, which heats it. 

If your air conditioning system is running with low refrigerant levels, the system will struggle to cool your home and run almost constantly in an attempt to keep up with your cooling demands. This constant running and stress can overheat and eventually burn out the compressor. 

The compressor is an essential component of your air conditioner, so if it fails, you may be looking at a costly replacement. 

In cases where the compressor fails due to a lack of refrigerant, it may be more economical to purchase a whole new cooling system rather than pour money into a new compressor. 

Influx In Humidity

Air conditioning units dehumidify the air. When the air cools as it blows past the evaporator coils, moisture condenses out of the air and drips into the condensate pan. Warm air can physically hold more moisture than cool air, which is why the humidity condenses.

Humidity meter in home

Under regular operation, the AC unit will remove a large percentage of moisture from the air. However, if your air conditioning system is operating with low refrigerant levels, you may notice that the air in your home is becoming more humid. 

Signs of Overcharged and Undercharged Refrigerant

Overcharged or undercharged refrigerant can be problematic and can be caused by overfilling, underfilling, or a leak. Your air conditioning unit should contain the designated amount recommended by the manufacturer, since too much or too little can cause issues. You want it just right. 

HVAC Technician Checking Refrigerant Levels


If the refrigerant is overcharged in an air conditioning system, it will present several telltale indicators. Signs may include:

  • Increase in system pressure
  • Flooding of refrigerant to the compressor during off cycles
  • Liquid slugging – happens when liquid refrigerant gets into the suction line and can damage the compressor
  • Noticeably louder compressor


Undercharged air conditioning systems may exhibit several signs, including:

  • Hot evaporator coils
  • Hissing or gurgling sounds during the cooling cycle
  • An overheated compressor that turns on and off frequently
  • Lack of cooling capacity
  • Low operating refrigerant pressure
  • Low suction or discharge pressure

Both overcharged and undercharged refrigerants in air conditioning systems may lead to expensive repairs. The system’s efficiency is usually compromised if it is overcharged or undercharged, leading to higher electric bills as the system tries to keep up. 

Why Should You Not Add A Refrigerant To Your AC By Yourself?

The refrigerant in your air conditioner is not safe for untrained individuals to handle. Only trained HVAC technicians who are EPA-certified should handle hazardous products like refrigerants. Not only is refrigerant terrible for you, but it is also terrible for the environment as it depletes ozone. 

Health Consequences

Refrigerant leaks can lead to refrigerant poisoning. Freon, a common refrigerant used in older systems, as well as other refrigerants, are heavier than air, so they sink to the floor. 

Children and small pets are at higher risk for refrigerant poisoning as they are closer to the floor and have smaller lungs. Adults will notice the symptoms last.

Symptoms of refrigerant poisoning range in severity. Mild to moderate symptoms include:

  • Headaches
  • Nausea
  • Vomiting
  • Dizziness
  • Vomiting
  • Irritation of the ears, eyes, and throat

Severe symptoms include:

  • Difficulty breathing
  • Loss of consciousness
  • Seizures
  • Fluid buildup in the lungs
  • Internal bleeding
  • Vomiting blood
  • Irregular heartbeat
  • Coma 
  • Sudden death

If you think there may be a refrigerant leak in your home air conditioning unit, you should contact our team of HVAC professionals immediately and evacuate the area. 

Most of these health effects will dissipate after leaving the area contaminated with refrigerant and moving to an area with clean air. However, if you continue to experience the effects of inhalation, you should seek medical attention as soon as possible. 

Overfilled or Underfilled

Even though refrigerants do not need to be “topped off,” the system may require additional refrigerants if they leak. With that said, an HVAC technician will need to repair the leak before recharging the system. If the refrigerant is overfilled or underfilled, damage can occur. 

Overfilled refrigerants can cause damage to the compressor. This happens because excess refrigerant can build up inside the compressor, generate a higher pressure and temperature than normal, and wreak havoc.

If the refrigerant is underfilled, another set of issues accompanies it. The lack of refrigerant cycling through the unit can lead to poor functionality, a higher electric bill, and warm air pumping out of the vents, among other things. 

Environmental Effects

Refrigerants, including Freon, are hydrochlorofluorocarbons (HCFCs) and are toxic to the environment. The chemicals found in refrigerants make their way up to the stratosphere. They deplete the ozone layer in the stratosphere, which helps to protect people from ultraviolet radiation. 

Thankfully, our HVAC contractors are EPA-certified and know how to handle the refrigerant safely and protect the environment.

If you don’t have training in the appropriate safety methods, you should not handle refrigerant. Plus, most homeowners don’t have the proper tools to recharge refrigerants in air conditioners, nor can they buy them on the open market. 

Enlisting the assistance of an HVAC contractor if you have any questions about your HVAC system or need your refrigerant recharged is always the best course of action. Tinkering with refrigerant inside your AC unit can be very dangerous. 

How Much Does It Cost To Have Your AC Unit ReCharged?

Air conditioning systems that do not run appropriately not only waste money but are incredibly inconvenient. Recognizing early signs of undercharged systems can help save money in the long run to avoid more severe, costly failures down the line. 

In most cases, recharging the central air conditioner in your home will cost an average of $150. The repair of leaks or other forms of damage to the unit may cost more.

Air conditioning repairs associated with leaks fluctuate drastically based on the type of damage, but generally, costs vary between $150 and $550 on average. 

If you have a damaged compressor due to the depletion of refrigerant, and you purchase a new unit, you will be looking at installations that cost between $3,500 and $7,500. 

Installation of a new condenser coil or new evaporator coil due to refrigerant leaks typically costs between $900 and $2,800. If the refrigerant leak is on a refrigerant line, that costs $200 to $750 to repair (on average). 

How Can A HVAC Contractor Help?

You should enlist the help of our HVAC pros if your air conditioning unit is leaking refrigerant right away. Undercharged refrigerant in your HVAC system may be the culprit of inadequate cooling. If you’re sweating and your AC unit is constantly running, get your system checked out. 

It is essential to seek the help of an HVAC professional, as incorrectly charging the refrigerant can lead to a host of issues, including expensive repairs, health hazards, and environmental damage. 

Passing the process to our trained professionals will ensure the job is done right. Our HVAC technicians have the necessary tools, training, and EPA certifications to recharge the refrigerant in your air conditioning unit safely. They will also check for signs that the refrigerant is overcharged or undercharged, preventing future issues. 

To avoid costly repairs down the road, ensure you service your air conditioning unit regularly. Our HVAC technicians can diagnose and fix all problems with air conditioning systems, furnaces, heat pumps, and more.

Meet Your HVAC Expert

Lester Mclaughlin

HVAC systems are highly technical and often is the most misunderstood part of the house. From ductwork to heat pumps, I've been exposed to all sorts of issues facing homeowners. It really irks me when a homeowner is given bad advice like refilling freon vs fixing a leak in the system. I'm here to help our website readers with their heating and a/c problems.
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