Why is my AC making a hissing noise? 

A hissing noise inside your HVAC system is not something to be disregarded. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating from your ducts, then you may have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound could be a sign for any of these things, but we’ll try to narrow it down a little further. 

Does the hissing sound end after a few seconds? 

If you hear a hissing noise that ends after a few seconds, you may not have any issues. That can be refrigerant in your expansion valve, which is part and parcel of the normal operation of your HVAC unit. 

Is the AC Making a Hissing Sound with Bubbling Noises? 

Are you hearing a bubbling sound along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak presents itself, you may hear a light hissing sound as the refrigerant escapes from the leak. The coolant escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, shut down the unit and call a expert HVAC company to come take a look. 

If the issue is a valve leak, it should be repaired by a professional as soon as possible. The job of the valves is to regulate the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will often intensify, which can be a signal if you’re looking for the cause. You need to maintain adequate pressure in your system for it operate correctly, and any leak will create additional health and maintenance problems. It’s best to get this fixed post haste if possible. 

Are Hissing Noises Coming from the Compressor? 

The compressor can be located in the outdoor air conditioning unit, which is also known as a condenser. Listen quietly for the hissing noise. If it turns out that the compressor is the issue, this could be an unsafe situation because it is a signal that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner immediately and call a professional technician. 

Photo of AC unit showing location of compressor

Compressors are some of the most costly parts to repair or replace inside an air conditioner. Compressors are the part responsible for pushing refrigerant through the system. You cannot run an AC and cool your home without a compressor. The pricing changes based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in your AC, you would need to replace it with another two stage compressor. It’s impossible to upgrade or downgrade the compressor type – your unit has specific requirements for what compressors are installed in order to operate safely. While it’s impossible to provide estimates because of the variable costs, the expense is often big enough to think about a replacement in older ACs. This is why it’s critical to shut off the air conditioning and call a trustworthy HVAC company if you hear hissing sounds coming from the compressor. 

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