What Causes Low Freon in AC or Car (incl. Symptoms and How to Fix)

What Causes Low Freon in AC or Car

Have you ever wondered what causes low freon in AC or Car? Look no more. We´ve got you covered.

Although refrigerants such as freon will be obsolete in the future, many people still have freon-based AC systems which may be prone to leakages.

If your AC is not working as well as it once did, you may be wondering what caused your freon levels to drop.

The causes of low freon in your AC may be due to defective factory parts, poor installation, or general wear and tear over time. Low freon Symptoms include poor cooling performance, ice build-up, and hissing sounds in your AC. You should fix or replace the faulty parts or buy a new AC system entirely.

There are several reasons why your AC is no longer cooling you in the hot summer months and the main culprit is freon leakages.

If you wish to know why your AC may be leaking, what to look out for and how to detect and fix the problem, please read on. 

What is Freon in ACs?

Freons are nonflammable and stable gasses or liquids typically used as refrigerants and aerosol propellants including chlorofluorocarbons  (CFCs) and hydrochlorofluorocarbons (HCFCs) such as chlorodifluoromethane

 Freons are low boiling, inert compounds of fluorine, carbon, and often chlorine that are often harmful to the environment.

The term freon is actually the brand name of a number of trademark refrigerants manufactured by E.I. du Pont de Nemours ; Company including:

  • R-12
  • R-13BI
  • R-22
  • R-410A 
  • R 502
  • R-503.  

Read also: What Type of Freon Goes In RV Air Conditioner? // R-22 Refrigerant

How Does Freon Work in an AC System?

Your AC system moves the refrigerant through a system of coils visa a compressor, moving the freon between a liquid and vapor state.

When the freon cools down to a liquid form it absorbs the heat from the external air and pushes the cold air out.

Read also: What is a Non-ducted RV Air Conditioner? (Ducted vs. Non-ducted)

The constant cycle of cooled and heated air provides the cooling you experience in your car or home AC system.

 First, the AC compresses the freon making it superheated in the form of vapor. Then the refrigerant moves through a series of coils that condense the vapor into liquid form.

 The freon then travels to the evaporator coils which convert it back to a low-pressure freon gas that cools the air in your AC area by absorbing heat and lowering the air temperature.  

Refrigerants How they work in HVAC systems >> Check out the video below:

What Are the Causes Of Low AC Freon?

Freon is a fully operational AC system with no faults or leakages that should last the lifespan of the unit.

Freon does not ‘get used up’ and the refrigerant should remain at the same level or ‘charge’ continuously circulating with the closed system. The main causes of low freon levels are when:

  • The refrigerant charge (or amount of freon in the system) does not match the manufacturer’s specifications 
  • The components such as the coils and joints have become corroded and created cracks or holes where the refrigerant may escape from the system.
  • The AC system is defective from a factory fault.

If you are trying to establish why your AC is showing signs of low freon, here are some of the main causes in more detail.

Read also: Will Low Freon Damage a Compressor? (Easy Explained)

Copper Tube Corrosion 

Most HVAC systems have metal components that may be susceptible to corrosion. The copper tube walls found in the indoor coil are prone to cracks and holes caused by the corrosive action of chemical contaminants such as aerosols, paint fumes, and even vehicle and industrial air pollutants. 

“When chemicals, particularly those with high chloride levels pass across the copper evaporator coils they cause a chemical reaction to occur.”

The caustic chemicals condensate and collect on the coil leading to pitting and formicary corrosion, which is small tunnels of corrosion that occur below the tube surface that eventually eat their way to the interior pipe surface and cause leakage. 

Joint and Connection Erosion

Flared joints and Schrader valves are often the culprits behind freon leakage in ACs.

while these joints are convenient to use but are often a weak point when it comes to protecting from erosion-based leakages.

Brazed joints are also a potential leakage site, commonly caused by poor brazing, inadequate pipe support, and lack of vibration protection.

Weld joints may cycle through high heat variations a hundred times in one day and the stress and pressure of expansion and contraction may result in fractures.

Often leaks in connections and joints are due to poor workmanship and brazing skills and low-quality materials such as the silver content of solder.

However, even good-quality installation and fittings can become thinned out and eroded over the course of their lifespan. 

Poor Installation

Poor installation by unprofessional technicians may cause a host of problems including faulty connections to ductwork, improper sizing of load calculation, and failure to calibrate the system thermostat.

Poor installation may result in improper charging of the refrigerant that may cause your AC system to freeze up, a common cause of Freon leakages. 

Read also: This Is Why Your RV Air Conditioner Is So Loud – [Do This First]

Defective Factory Components

Your AC may be leaking freons through no fault of your own due to factory defects that the manufacturers did not detect.

Incorrectly fitted parts, poor assembly, or missing parts may be the cause of a potential leak as well as poor handling of the AC unit itself. 

It is important to consult a trained technician in this case, as you may stand to lose your warranty if you conduct alterations without professional assistance. 

Low Freon Symptoms In Car or AC?

At room temperature, freon is colorless and almost odorless that is four times heavier than air.

Even though freon does have a characteristic slightly sweet, ether-like odor, the freon sinks to the floor, and the chances of detecting the leak by smell are unlikely.

If you suspect your car or AC has a freon leak, you should look out for the following symptoms: 

Poor Cooling Performance

One of the first noticeable signs of a freon leak is the altered cooling capacity of your AC. The unit may blow warm air or show a marked decrease in its cooling performance.

A lower airflow from what you are used to may also point to a leakage issue.

Your Home Takes Longer To Cool Down

If your AC has a freon leakage you may notice that your home takes longer to cool than normal. Freon leaks lower the performance capacity of your AC system resulting in a gradual loss of cooling capacity.

In the initial stages of the leak, this may be an increase in time the ambient temperature of your space becomes noticeably cooler.

You May hear Hissing Sounds

Persistent whistling or hissing sounds could be a sign of a freon leak.

The refrigerant lines or internal valve or compressor issue will often make a hissing or bubbling sound as the gas is released from the leaking pipes and these sounds typically worsen if left unchecked to a gurgling noise. 

Your Electricity Bill Goes Up

Freon leaks cause your AC system to work a lot harder than normal and utilize more electricity in the process.

If your monthly electricity bills are steadily climbing or have suddenly jumped, it may be due to a leakage in your AC.

Ice Build-Up on Lines and Coils

The freon in your evaporator coils is responsible for cooling the air. When there is a freon leakage level of the refrigerant drops the corresponding drop in pressure.

When the pressure drops, the refrigerant begins to expand and cool and the low temperatures cause the normal condensation to freeze and form ice build up on your evaporator coils.  

With normal levels of refrigerant, the evaporator will be around the freezing temperature of water.

The warmer air moves over these coils the moisture in the air will condense forming harmless drips into the condensation drain. 

When a leakage lowers the freon levels, the will be lower than the freezing temperature of water and the condensation will freeze.

As the ice builds it restricts airflow through the coils preventing the freon from absorbing more heat from the indoor air forming ice further down the coils. 

Symptoms of Low Refrigerant Charge >> Check out the video below:

What Can I Do if My AC Is Leaking Freon?

If your leak is located in a fitting or line it is relatively inexpensive to repair or change the faulty part out.

If the leak is in your exchanger coils, you would need to replace the part unless it was in an area that is open to brazing.

If the leak is in the compressor( compressor bypass leak) then the costs may be prohibitive as this is the most expensive part to fix. 

As freon-based ACs are no longer in manufacture, your system is most probably older and nearer the end of its lifespan.

Keep in mind that soon the R22 refrigerants will no longer in production so it makes sense to think of replacing your AC system entirely.

It is also a more environmentally conscious decision beyond the practicalities and expense. 

Repair options for Low Freon (How To Fix)

R-22 based systems will typically be older AC units due to the US Department of Energy ban on CFC production effected in 1995.

The replacement HCFCs are also being phased out as refrigerants with production and import halted by 2020 and all production and important stopped by 2030.

It makes sense to rathe replace your AC system with a newer version as the availability of freon and its price has increased with scarcity.

It is of paramount importance to consult a qualified AC technician when attempting to repair your leakage as there are potential hazards involved with the process.

However, to fix or repair low freon, you need to follow the steps below which includes:

  • Safe removal of the remaining refrigerant 
  • Conduct repairs or replace the faulty component
  • Larger freon leaks will need to be soldered and the evaporator and condenser coils replaced
  • Check for additional leaks by pressurizing your AC system
  • Vacuum your AC system and recharge it with a new refrigerant, as old refrigerant may turn your system acidic and wear down the coils and pipes.

Options for AC Leak Repair

  • Leak seal treatment is a temporary fix to tide you over until the proper repair is conducted
  • Adding more freon is a less logical option as it will not repair the leakage which will return the next cooling season
  • Get a new AC system if the repairs are too costly and seek advice from a qualified AC technician on how to proceed. 

How Do I Test For Freon Leakage in My AC?

Experts suggest that one should contact a reputable ACV repair company in your area as you may further damage your system without the technical experience in AC repairs.

 Although freon is less harmful than other solvents, there have been freon-induced fatalities over the years.

The fact that freon is four times heavier than air also means that pets and children are at higher risk of freon-based illness. 

With the aid of your AC technician, the most common ways to test for freon leaks are:

Dye Detection

With dye detection, a fluorescent dye is circulated through the AC system and then isolated by means of a detection lamp.

AC repair companies have the specialized equipment to conduct the test in a matter of minutes and identify the specific areas of leakage for repairs or replacement. This test may also be run whether your AC is working or not. 

Electronic Detection

There are a variety of electronic methods to detect freon leakage in your AC in a precise and efficient manner. These methods use specialized equipment to suit your particular refrigerant and AC stem. The most common testing methods are as follows:

Negative Corona Testing

Negative corona testing or corona suppression takes the form of an instrument with two electrodes with a current passing between them.

When a refrigerant gas passes between these electrodes, the ‘baseline ‘shows interference and a drop in current. The higher the interference the larger the leak of refrigerant.

Heated Diode Leak Detection

When using the heated diode detection, the refrigerant is heated to the point where the bonds of the molecules are broken apart.

This results in the release of positively charged concentrations of chemicals such as fluorine or chlorine which triggers an alarm.

Fluorine and chlorine are common components in CFCs and HCFCs on the market today.  This technology is less likely to trigger false alarms than negative corona detection. 

Nitrogen Leakage Detection

An AC professional would first empty all the refrigerant from your unit and replace the gas with compressed nitrogen.

This test works much the same way as one isolates leaks in a bicycle tire through the sound of the escaping air.

The greater pressure of nitrogen moving through the AC system causes a distinct hissing sound as it exits the system through undetected areas of leakage.

The Soap Bubble Technique

The soap bubble test is one of the common ways to test for freon leakages and involves sending warm, soapy water through your AC system. 

However, it is not always accurate as it may be hard to tell where the bubbles arise.

It is also important to use soap without corrosive elements as this could damage your AC system. this type of test works best in tandem with a more accurate testing method such as electronic leak detection. 

What Shall I Do If My AC Is Leaking Freon?

Opening windows and doors and utilizing fans to circulate the air in the affected area

  • Remove all pets and children to a well-ventilated area preferably outdoor and monitor them for any signs of illness
  • Call an AC technician immediately to solve your leakage problems. 


Due to the environmental impact of CFCs and HCFCs, by the year 2030 freon should be a thing of the past in America.

Existing AC systems using freon should be nearing their lifespan and it is a logical process that when their systems expire they will move on to less environmentally harmful refrigerants.

 In the meantime, ensure that your freon is at safe levels and watch out for the above signs of freon leakage. 



Mike Gilmour

Hi, I'm Mike, co-founder, and editor of RV and Playa. My passion is traveling (with my RV) and enjoying the day at the beach (Playa)! Well, I originally created this blog as a way to share what I've learned by experimenting with the RV lifestyle, and I want to help others develop in life through new skills and opportunities.

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