african american woman smelling freon from air conditioner leak

“What does Freon smell like?” is a common question with a debatable answer. But before we get into its odor, let’s talk about what Freon is. Freon is a colorless liquid or gas used to cool warm air. Freon is a chemical compound used as a refrigerant in some air conditioning units, freezers, and even dehumidifiers. Freon is a brand name trademarked by the Chemours Company, but the name has become a generic term, like Band-Aid, for any refrigerant. The most common type of Freon is Freon 22, also known by the generic name R-22.

Without refrigerant, your air conditioning system would not possess any cooling power. The refrigerant absorbs heat from your home’s air, and the freshly cooled air is blown into your home through your vents. Freon continually cycles from gas to liquid as it flows through the various parts of the air conditioner in a circuit. Occasionally, air conditioning systems develop a Freon leak.

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Does Freon smell?

Freon is clear, tasteless, and generally odorless; however, Freon’s odor may be detected in high concentrations. Freon smells differently to different people. People describe Freon as having a sweet smell, chemical odor, or reminiscent of the scents of nail polish remover, acetone, paint, paint thinner, and gasoline.

An odor emanating from your air conditioner does not always indicate a Freon leak. Other odors, such as vinegar or urine indicate other air conditioner problems. You can read about them here: Why does my air conditioner smell?

Is Freon Dangerous?

Inhaling Freon deliberately is dangerous; leaking Freon from an air conditioner poses little to no risk to your health. You will unlikely experience any symptoms from a Freon leak since Freon quickly dissipates into the air, and leaks usually occur outside. If a leak appears inside the home, you could experience mild symptoms like headaches and nausea. Generally, symptoms will only present if you have been sitting near the leak for a prolonged period.

Ventilating the house by opening windows and turning on a fan helps to dissipate the Freon and reduces the likelihood of ill effects. Freon gas is heavier than air, so it sinks to ground level. Therefore, children and pets are more susceptible. Consider leaving the premises until the leak is repaired.

What happens if you smell Freon?

If you smell Freon, immediately turn off the thermostat and call a local HVAC professional. Subsequent damage to the air conditioner can occur from running it with a leak. Also, leaking Freon harms the environment and can affect humans and pets. Freon will continue to circulate after shutting off the thermostat because the system is pressurized, so you should have a professional inspect your air conditioning unit as soon as possible.

Freon leaks often occur in the evaporator coils, valves, “U” connectors, or copper lines and tubing. HVAC professionals check for leaks using various methods. One method involves applying soapy water to the welds and joints, parts that often develop leaks. Bubbles will appear at the leak’s location. Another approach is to add ultraviolet (UV) dye to the air conditioner’s Freon. Any refrigerant that leaks out will fluoresce. An electronic detector is a third, extremely accurate method of finding leaks. This device can detect leaks as small as a tenth of an ounce per year.

HVAC professionals can only repair refrigerant leaks. An air conditioning system requires a certain amount of refrigerant to work properly and has to be “recharged” or refilled after the leak is repaired. A refrigerant certification is required to purchase HVAC grade R22 and R410A refrigerants.

HVAC professional testing the amount of freon refrigerant in air conditioner unit

In the 1990s, AC Freon (R22) was determined to be harmful to the ozone layer, and the United States began phasing it out of use. Therefore, newer air conditioning units use another refrigerant, R410A. Old air conditioning units can continue to use Freon, but no Freon may be produced or imported to the United States as of 2020. Consequently, Freon from the remaining stock can be expensive to purchase. If your air conditioner or heat pump uses Freon22 and is leaking, you’ll likely have to replace it with a new unit that uses R410A.

How long does the Freon smell last?

How long the Freon smell lasts depends on the size of the leak and the home’s ventilation. The odor from large leaks may last longer, especially if ventilation is poor. Opening the windows and turning on a fan will help to circulate the air and dissipate the odor.

Freon leaks that go undetected will gradually worsen over time. Factors such as the size of the leak and the amount of pressure affect how quickly the refrigerant leaks out. It could take minutes or years for enough Freon to leak out that the air conditioning system stops working.

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Causes of a Freon Leak

Several circumstances can cause Freon leaks:

  • Excessive vibration
  • Improper installation
  • Factory defects
  • Wear and tear
  • Corrosion
  • Damage

Excessive Vibration

Isolation inhibitors reduce vibrations within the air conditioning unit. These parts wear out over time, and refrigerant lines can crack from vibrating excessively.

Improper Installation

The unit might excessively vibrate if it was installed improperly. Excessive vibration can cause refrigerant lines to crack.

Factory Defects

The air conditioner may have always been defective. If numerous issues with the unit have arisen since it was installed, a factory defect may be the cause.

Wear and Tear

Air conditioner parts wear out over time. The welds on the copper refrigerant lines are a common source of Freon leaks.


Air conditioners are made from various metals such as aluminum, copper, and galvanized steel. Parts corrode and rust due to air pollutants, the elements, and even animal urine.


Air conditioning units can sustain damage from lawnmowers shooting out sticks and rocks, children playing on them, and animals nesting in them.


Freon is a colorless and generally odorless gas or liquid, though an odor may be detected if a large amount leaks from the air conditioning system. Some people describe the smell as sweet; others think it resembles a chemical like nail polish remover.

If you suspect a Freon leak, immediately turn off the air conditioning system, ventilate the house, and call an HVAC technician. Running the system with a leak can be damaging, and Freon will continue to leak even when the system is off. A technician certified in the handling of refrigerants will inspect the unit for leaks and repair them.

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