Do you notice a suspicious hissing noise after your air conditioner turns off? The good news is there isn’t a snake in your house, the bad news is there may be something wrong with your AC compressor.

What is an AC compressor? An AC compressor, or air conditioning compressor, is an important part of an air conditioning system. It is responsible for circulating and compressing refrigerant gas within the AC system, facilitating the transfer of heat, and enabling the cooling process. The AC compressor plays a crucial role in the refrigeration cycle of an air conditioning system, allowing the continuous transfer of heat and ensuring efficient cooling.

In addition to reliably cooling your Camarillo, CA home, your air conditioner should offer ongoing humidity regulation, limited air filtration, and overall quiet functioning. Although there a several sounds that are commonly part of regular AC operation, certain noises are often cause for alarm. Hissing, especially when it occurs at the outside compressor, is one of them.

Read on to find out what hissing sounds at the AC compressor usually mean and how one of our Mom-Approved HVAC technicians can help!

Your AC Compressor Is Highly Pressurized

Central air conditioners typically have two primary units: their indoor air handlers and their outside condensers. Your air conditioner’s outdoor condenser houses its condenser coil, where the heat that’s been absorbed from your indoor air is released. The outside condenser also houses your AC compressor. This unit pressurizes the refrigerant and pumps it throughout the entire cooling system. During regular AC operation, pressure levels within the condenser rise and fall relative to the movement of refrigerant. Thus, if you stand next to your air conditioner’s condenser for a complete cooling cycle, you may find that a small amount of hissing is entirely normal, especially just after a cooling cycle has ended.

Hissing from the AC compressor is usually a sign of serious problems when it becomes particularly loud or high-pitched and when it’s a sound that the unit has never made before. Even if your AC is getting along in age and has become increasingly noisy throughout the years, you should have a licensed HVAC company inspect any hissing sounds that suddenly develop.

Refrigerant Leaks and Impending Compressor Collapse

Loud or high-pitched hissing at your AC compressor could signify a refrigerant leak. When your air conditioner cycles down and refrigerant is no longer being pumped throughout the cooling system, slight hissing indicates natural, gradual depressurization. During AC operation, high-pitched or loud hissing means that the compressor attempts to create the necessary pressure for refrigerant movement, but the rapid refrigerant loss is inhibiting it.

If you have a slow and relatively small refrigerant leak, your air conditioner could continue functioning for quite some time. However, you’ll likely notice a steady increase in the temperature of the air that’s coming out of your vents. You might additionally experience a marked rise in indoor humidity as well.

Decreased refrigerant prevents air conditioners from doing their jobs effectively. It also places tremendous strain on AC compressors. More significant and rapid refrigerant leaks will eventually cause your air conditioner to shut down. If you ignore high-pitched hissing noises coming from your outdoor AC unit, your AC compressor may even collapse. To stop a refrigerant leak from spiraling out of control, shut your air conditioner off as soon as you notice louder or higher-than-normal hissing and give our Mom-Approved team at AirWorks Solutions a call!

Excess Pressure Within the AC Compressor

It’s also possible for AC compressors to have too much pressure. This typically occurs after a poorly performed recharge service. If you’ve recently had your air conditioner’s refrigerant recharged, the HVAC technician that handled this job may have added too much.

Many modern air conditioners have built-in failsafe measures that automatically shut them off when pressure rises too high. If you heard a loud, high-pitched shrieking noise coming from your AC compressor just before an automatic shutdown, you should have your air conditioner’s refrigerant level checked. When diagnosing the underlying problem, an HVAC technician will also look for blockages along the refrigerant line.

Shifting Soil Beneath Your AC Condenser’s Concrete Slab

AC condensers are usually installed on concrete or composite pads. These pads create the stable, level surfaces condensers need to function optimally. Soil compaction, shifting soil, soil erosion, and other landscaping and grading issues can cause these supporting pads to shift, crack, or tilt. Not only can this leave condensers slanted, precariously balanced, and unable to support reliable airflow, but it can also impact pressure within the AC compressor.

A Mom-Approved HVAC technician should always handle the physical adjustment of AC condensers or their underlying pads! If you’ve recently moved your condenser or added to the soil beneath its pad, newly developed hissing noises could be the result of your self-managed efforts.

Leaky or Damaged Valves

The refrigerant in your air conditioner passes through a throttling device as it moves from the indoor evaporator to the outdoor compressor. This throttling device is called a thermostatic expansive valve or TXV. It controls the amount of refrigerant that moves from unit to unit and the pressure that this refrigerant is under during transport. If your thermostatic expansive valve malfunctions or fails, the pressure within your cooling system could fluctuate wildly. This will create hissing noises throughout the entire cooling cycle and may lead to shrill, shrieking sounds during times when pressure mounts.

Thermostatic expansion valves don’t have firmly set lifespans, but these components often fail long before air conditioners fail themselves. With most air conditioners lasting between 15 and 20 years, it’s not uncommon to have a TXV replaced at least once. Given their ongoing exposure to high pressure, these components are subjected to extraordinary amounts of wear throughout the years, especially when air conditioners are used all of the time.

In addition to hissing at the outdoor compressor, several signs of a failing or failed TXV include:

  • Warm air coming out of HVAC air vents
  • The formation of frost on the TXV
  • Increases in indoor humidity
  • Higher than normal home energy bills

The best way to catch and replace a failing TXV before it causes serious compressor issues is by regularly scheduling an annual AC maintenance service with our Mom-Approved team!

Leaky HVAC Air Ducts

Hissing noises are frequently attributed to malfunctioning compressors and refrigerant leaks. However, they can also be the result of air loss due to aging, torn, or crushed HVAC air ducts. If you hear a faint hissing noise while indoors that appears to be coming from the same side yard or backyard area that your AC condenser is installed in, it may be that ducting just in front of the adjacent exterior wall is experiencing air loss.

Leaky ducts deposit cooled air behind drywall, where it has virtually no impact on indoor temperatures at all. As fast-moving air escapes ducting, it tends to make a whispering or light hissing noise. It’s easy to assume that these sounds are coming from outside, but if you stand near your compressor and cannot hear them, you should have your ductwork inspected.

Leaks are common in air ducts that are more than ten years old. Much like air conditioners and furnaces, HVAC air ducts have finite lifespans. Your air ducts should be replaced every 10 to 15 years. If they’re currently more than a decade old and leaking, having new ones put in will likely prove more cost-effective than paying for a low-cost and temporary patch.

Need Help With Your AC Compressor? Our Mom-Approved Team Can Handle That!

Since 2010, we’ve been proudly serving the families of Camarillo, CA, and the surrounding communities. We’re committed to helping our clients save money, improve their home comfort, and extend the lifespans of their cooling systems. We’re all about getting your HVAC systems back to working order fast so you can get back to enjoying the little things in life. We offer air conditioner, heat pump, and furnace installation, maintenance, and repair services. You can also turn to us for cutting-edge indoor air quality solutions.

If your AC compressor is hissing, give AirWorks Solutions a call now!

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