Low AC Refrigerant: 5 Signs and Potential Problems for Your AC

low ac refrigerant level and signs ac is low on freon

Jake Smith, Online Marketing Strategist
Technically Reviewed by Jake Smith, Online Marketing Strategist on May 3, 2024 | Written by Alpha Mechanical Editorial Contributors

Role of Refrigerant (Freon) in Air Conditioner Work.

Refrigerant in an AC is a substance that absorbs heat and releases it, turning into a gas and a liquid during the process. It starts in the evaporator coil where the warm air transfers its heat to the refrigerant. After this it goes to the compressor, where it increases the temperature and pressure and sends it outdoors to the outdoor condenser coil. The refrigerant releases the heat from inside and is passed through an expansion valve which cools it off even more and it is now ready to restart the process.

When your AC unit is low on refrigerant, it has to work harder to cool your home, which can lead to higher electricity bills and breakdowns. Once diagnosed, call a professional HCAC company to fix the problem.

Now let’s discuss how to tell if your air conditioner needs freon.

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Low Freon Symptoms

Warm air blowing from the vents

This indicates the AC is struggling to absorb heat indoors. Normally, refrigerant absorbs heat from the air, making it colder. But with low refrigerant, there’s less capacity to absorb heat, causing warm air to be circulated back into your home. Warm air blowing after your system runs for an adequate amount of time is one of the bigger symptoms of low freon.

Taking a longer time to cool your home

Missing refrigerant makes it harder for the AC to reach the desired temperature. The system has to work for a longer duration to compensate, leading to increased running time and cooler temperatures taking much longer to achieve.

Ice building up on the refrigerant line

When refrigerant levels are low, the remaining refrigerant absorbs less heat and gets colder. It can get so cold that it starts to freeze within the evaporator coil, forming ice on the refrigerant line. This ice will eventually melt resulting in water dripping or pooling underneath.

Higher electricity bills

A low refrigerant level forces the AC to work harder and longer to cool your home. This increased workload translates to higher energy consumption, leading to spikes in your electricity bills.

Unusual noises coming from the unit

Low AC refrigerant can put a strain on the AC compressor, causing it to work under duress. This stress can result in strange noises like grinding or hissing sounds coming from the unit. A hissing or bubbling noise indicates a leak, hissing is escaping as a gas, while bubbling indicates it is escaping as a liquid.

Low AC Refrigerant Can Cause...

A frozen evaporator coil.

This happens because the refrigerant absorbs heat from the indoor air, and when there is not enough refrigerant, it can’t absorb enough heat. This causes the coil to get too cold and freeze surrounding water in the air on the evaporator coil.

Damage to the compressor.

The compressor is the part of the air conditioner that pumps the refrigerant throughout the system. If there is not enough refrigerant, the compressor will have to work harder to circulate the refrigerant, which can cause it to overheat and burn out.

Your air conditioner to be less efficient.

This is caused by the air conditioner having to work harder, as well as more often to cool your home. This will use more energy as well as reduce the lifespan of your AC system, while making repairs unrelated to low freon more likely.

An increase in the humidity in your home.

Air conditioners remove moisture from the air as they cool it. If there is not enough refrigerant, the air conditioner won’t be able to remove as much moisture from the air, which will make your home feel more humid.

Reduced cooling capacity.

When there is low air conditioner refrigerant your system will cool less, or not at all

What Causes Refrigerant Leaks
and How to Prevent it?


Water reacting with the copper lines can also lead to leaks. Exposure to water, even humidity in the air, can cause water droplets to form on copper lines. This can react and cause the copper to corrode.


Acid and chemicals can corrode at a quicker pace than water. Be sure to check any cleaners that you use on the pipes for compatibility with copper. Unique to copper is formicary corrosion, caused by formic acid on copper. The source can be building materials, certain cleaners, or even furniture. Acid rain can also lead to corrosion.

Improper Installation

Improper installation can also directly cause leaks if the connections between refrigerant lines and components are not done correctly. It can also be damaging if placed in bad locations that expose it to corrosion.


Accidental punctures from yard work, tools, or even rodents can also cause refrigerant leaks. It is important to be careful when near your AC unit.

Lack Of maintenance

Lack of maintenance causes small easily fixable problems, such as moisture, to become larger and costlier issues.

Other Issues

  • Lesser known causes of corrosion include having different metals, such as steel or iron, directly connected to the line.
  • Uncontrolled electrical currents can cause rapid damage to copper lines.
  • Loose assembly joints can also develop leaks over time, especially if the AC unit is subjected to vibrations.

When freon is low or completely empty, that is a good time to think about what refrigerant you are using.

R-22 is not legal to produce in the USA, so any refills will be more costly than replacements. On top of that, if a top up is the better choice over completely refilling, but the supplies of R-22 have run out, you will have to swap regardless. The refrigerants that can be swapped to will be indicated by the sticker or plate on the compressor or evaporator. Make sure to check this, as putting in the wrong refrigerant can damage an air conditioning system.

A qualified technician will check for low refrigerant charge symptoms during routine maintenance, so make sure to mention any that you have experienced to pay special attention to. They can also identify and replace worn out parts before they fail and cause leaks.

Avoid hitting the outdoor unit with yard tools or objects, as this can damage the refrigerant lines and cause leaks.

Regular maintenance is the best way to catch small issues before they become big problems.

So, how do I find a freon leak in HVAC systems early rather than later?

Keep an eye out for signs AC is low on freon, such as if your home takes longer to cool and the vents aren’t blowing as much cool air. This, along with unusual sounds or ice on the refrigerant line, could signal low AC refrigerant levels.

Contact Alpha Mechanical for Recharging the Refrigerant in Your Air Conditioner in the Sacramento Area

What do I do if I find signs of the freon in my system being low?

Contact Alpha Mechanical, your trusted 5-star HVAC contractor, is ready for any AC repair in Sacramento.

We expertly diagnose and recharge refrigerant levels, getting your air conditioning system back to peak performance quickly and efficiently. With our dedication to quality service with attention to detail, our technicians are skilled in troubleshooting cooling problems and ensuring your AC system runs efficiently.

Contact Us at 916.848.5980 for any and all AC repair services in Sacramento.

Final Thoughts

Your air conditioner keeps you cool by using refrigerant to bring heat from indoors and release it outdoors.

When refrigerant runs low, your AC struggles. Some signs of low freon are warm air blowing from vents, cooling takes longer than normal, and strange noises emerge. Even worse, the compressor can get damaged, leading to higher electricity bills and humidity.

Leaks are the cause of low AC refrigerant, caused by wear and tear, corrosion, bumps, or improper installation. Regular maintenance by a professional can prevent these leaks and catch low refrigerant early.

If you suspect trouble based on the signs mentioned, call Alpha Mechanical, your Sacramento area’s trusted AC experts. We’ll diagnose and repair the problem or problems to ensure your AC system is up to par. If it is necessary we are fully capable of any air conditioner installation in Sacramento.

Frequently Asked Questions

How to tell if AC unit is low on freon?

Signs of low freon include blowing warm air regardless of how long it’s running, taking longer than normal to cool down, or having ice on the refrigerant line.

You might also hear strange noises or see a spike in your electricity bill.

Is it possible to retrofit an older air conditioner to use a new refrigerant?

Yes, particularly with the ban of R-22 freon, sometimes it is not possible to refill AC systems with refrigerants.

A full refill instead of mixing in a new refrigerant is necessary because different refrigerants need different pressure and sometimes different systems.

Can I recharge the refrigerant in my air conditioner myself?

It is highly recommended for a professional to recharge freon, as it can be dangerous when not handled properly, as well as a band aid solution.

Without finding where the refrigerant leaks, and fixing it, the new refrigerant will simply seep through the same place

Does low freon affect heat?

Freon is the part of an AC system that moves the heat, so when freon is low it has less heat moving. This may affect your cooling in a few ways. Warm air could flow from vents due to the heat not being moved elsewhere.

Even if cool air is flowing, the AC system has to work harder for the same result causing more cost in electricity, as well as more wear and tear on the system.

How to tell how much refrigerant is in an ac system?

The easiest way to measure freon in AC systems is to look at the pressure gauges for high or low pressure correlating to high or low refrigerant charge.

Checking The compressor/condenser, evaporator and piping and combining the results to see total charge in the system.

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