AC Making A Hissing Noise: Why and What To Do?

Is your AC making a hissing noise that’s causing concern? While some hissing noises are normal, indicating the flow of refrigerant through your AC unit, persistent or loud hissing can signal a problem that shouldn’t be ignored.

A hissing noise from your AC could be a minor issue, like a slightly loose valve, or a more serious concern, such as a refrigerant leak. When you hear a hissing sound coming from your air conditioner, it’s essential to investigate further. The hissing noise may be accompanied by other symptoms, such as reduced cooling capacity, warm air blowing from the vents, or increased energy bills.

The hissing noise may originate from various components of your air conditioning system, such as the compressor, expansion valve, or evaporator. Each of these parts plays a vital role in the cooling process.

In this article, we’ll explore the potential reasons behind your AC’s hissing noise and provide guidance on when it’s time to call in a professional HVAC technician.

6 Causes of a Hissing Noise in AC Units

1. Refrigerant Leak

A refrigerant leak is one of the most common causes of a hissing sound coming from your air conditioning unit. When refrigerant escapes due to a leak, it creates a hissing noise as it moves from a high-pressure area to a lower-pressure area.

A leak can occur at various points in the AC system, and it’s essential to address the issue promptly. Without refrigerant, your AC unit won’t be able to cool the air effectively, causing it to work harder and leading to further damage. Remember, they can cause toxicity, flammability, asphyxiation, and physical hazards.

2. Internal Valve Leak

An internal valve leak can also cause your AC to make a hissing noise. If a valve inside the unit is leaking, refrigerant can escape at high pressure, resulting in a hissing sound. The noise may be continuous or intermittent, depending on the size of the leak and the pressure within the system.

3. Compressor Issues

If you hear a hissing noise coming from your AC compressor, it could indicate internal damage or wear. A malfunctioning compressor can cause coolant leaks or pressure imbalances, leading to hissing sounds. This noise may signify that the compressor is struggling to maintain the necessary pressure levels for proper operation.

According to Climate Care, a well-maintained compressor should last about 12-15 years.

4. High Pressure in the System

Excessive pressure buildup within your air conditioning unit can cause refrigerant to escape from high-pressure areas, resulting in a hissing sound. High pressure can be caused by blockages, dirty condenser coils, or overcharging the system with refrigerant. When the pressure is too high, it puts strain on the components and can lead to leaks and other issues.

5. Expansion Valve Issues

A malfunctioning expansion valve can cause improper refrigerant flow, leading to pressure imbalances and hissing noises. If the valve is not working correctly, it can result in frost buildup on the coils and damage the compressor.

6. Normal Operational Sounds

Not all hissing sounds from your AC unit are cause for concern. Some hissing noises are normal during operation, particularly when the refrigerant expands and adjusts to pressure changes. Short, intermittent hissing is common when the AC starts or stops as the refrigerant pressure equalizes.

6 Solutions for a Hissing Noise in AC Units

1. Addressing Refrigerant Leaks

If you suspect a coolant leak is causing the hissing noise in your unit, it’s better to have a professional inspect your system. They can perform a visual inspection for signs of oil stains or ice buildup and use electronic leak detectors to pinpoint the exact location of the leak.

Once the leak is located, the technician will repair or replace the leaking component, such as hoses, connectors, or coils, to restore your AC’s performance. For proper functioning of your unit, a leak inspection must be conducted every 12 months.

2. Fixing Internal Valve Leaks

An internal valve leak can be the reason behind the hissing sound coming from your air conditioning unit. For minor leaks, tightening connections or replacing seals and gaskets may resolve the problem. However, significant leaks may require replacing the entire valve assembly to restore proper function.

3. Resolving Compressor Problems

If the hissing noise is due to compressor issues, an AC professional will diagnose the problem through inspection and testing of electrical components and refrigerant flow. Minor repairs may involve replacing worn-out seals, gaskets, or valves within the compressor.

In cases of extensive damage, replacing the entire compressor may be necessary to restore system efficiency. When selecting a new compressor, opt for one with a high Seasonal Energy Efficiency Ratio (SEER) rating for optimal energy efficiency and performance.

4. Managing System Pressure

To prevent hissing sounds caused by high pressure in your AC system, regular maintenance is key. A professional will check and clean the condenser coils to maintain efficient heat dissipation, monitor refrigerant levels, and adjust as needed to prevent overcharging. Installing pressure gauges can help keep track of system pressure and identify issues early.

4. Handling Expansion Valve Issues

If a faulty expansion valve is causing your AC to create a hissing noise, an expert will diagnose the issue by inspecting the valve and refrigerant flow patterns. Cleaning or replacing clogged filters and screens associated with the valve may resolve the problem. In some cases, replacing the valve with a new, compatible unit may be necessary to restore proper function.

5. Recognizing Normal Sounds

To differentiate between normal operational noises and issues, familiarize yourself with the typical sounds of your unit during normal operation. Note the duration and frequency of hissing sounds; short and intermittent sounds are often normal. Pay attention to any changes in the noise pattern, which may indicate emerging issues. If you’re unsure whether a hissing sound is cause for concern, it’s always best to consult with a local HVAC professional for guidance.

Tired Of A Hissing AC Unit? Call HVAC Angel

If your AC unit is making a hissing noise, it’s time to call in the experts at HVAC Angel. Our team of highly skilled technicians has the experience and equipment necessary to diagnose and fix any issue causing your AC to hiss.

We understand the frustration and discomfort that comes with a malfunctioning air conditioner, which is why we prioritize prompt and efficient service to get your home back to a comfortable temperature as quickly as possible.

At HVAC Angel, we invest in state-of-the-art leak detection tools, pressure gauges, and duct inspection cameras to pinpoint the source of the problem quickly and accurately. Our technicians undergo rigorous training to stay up-to-date with the latest techniques and technologies in the industry, so that we can handle any challenge your AC unit presents.

Whether it’s a refrigerant leak, a faulty valve, a clogged duct, or any other issue causing your AC to hiss, we have the knowledge and expertise to get your unit back up and running smoothly.

Don’t let a hissing AC unit disrupt your comfort or lead to costly repairs down the line. Trust HVAC Angel to provide prompt, professional, and reliable service that will have your AC running quietly and efficiently in no time. Contact HVAC Angel today to schedule your appointment and experience the difference that our expertise and dedication can make in your home’s comfort.

Frequently Asked Questions

1. Should I turn off my AC if it’s making noise?

If your AC is making unusual noises, including loud hissing, it’s best to turn it off and call a professional. Continuing to run the unit may cause further damage.

2. Is AC hissing noise normal?

While some brief hissing sounds are normal during AC startup and shutdown, persistent or loud hissing is not normal and may indicate a problem like a refrigerant leak.

3. Why is my AC hissing but no cold air?

A hissing AC unit that’s not producing cold air may have a coolant leak, preventing the system from cooling properly. A clogged air filter or duct can also restrict airflow.

4. Why is my AC making a hissing sound but not turning on?

If your AC is hissing but not turning on, it could be due to a compressor issue, an electrical problem, or a stuck valve. It’s best to have a professional diagnose the issue and get your ac repaired.