Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be ignored. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is originating from your ducts, then you may have leaking air ducts. This is annoying, but not necessarily a reason to worry. A hissing sound may indicate any of these things, but we’ll try to narrow it down further.

Does the hissing sound stop after a few seconds?

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

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound paired with a hissing sound? This can indicate a refrigerant leak. If a refrigerant leak presents itself, you might notice a slight hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a worrisome health concern. If you see signs of a refrigerant leak, turn off the AC and call a professional HVAC company to come inspect the system.

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 manage the pressurization of the refrigerant gas and left alone, the leak will worsen. When it does, the hissing sound will increase, which can be a sign if you’re looking for a cause. You need to maintain proper pressure in your system for it operate correctly, and any leak will create additional health and maintenance problems. You want to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is located in the exterior air conditioning unit, which is also called a condenser. Listen around here for the hissing noise. If you find the compressor is the issue, this could be a dangerous situation because it is a sign that the pressure inside the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner without delay and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly parts to repair or replace inside an air conditioner. Compressors are the part responsible for circulating refrigerant through the system. You cannot run an AC and cool your home sans compressor. The pricing is variable based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you will need to replace it with a two stage compressor. It’s impossible to upgrade or downgrade the compressor type - your unit has specific requirements for what components are installed and can’t be MacGyvered. While it’s impossible to say how much a compressor replacement is because of the variable costs, the expense is frequently large enough to consider a replacement in older ACs. This is why it’s so important to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.

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