Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be ignored. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is coming from your ductwork, then you could have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound could indicate any of these things, but we’ll try to narrow it down 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 problems. That could be refrigerant in your expansion valve, which is part and parcel of the normal day to day operation of your HVAC system.

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 may notice a slight hissing sound as the refrigerant escapes via the leak. It escapes as a gas and can be a worrisome health concern. If you see signs of a refrigerant leak, power down your HVAC and call a professional HVAC company to come inspect the system.

If the cause is a valve leak, it should be repaired by a technician as soon as possible. The job of the valves is to manage the pressurization of the refrigerant gas and without repair, the leak will worsen. When it does, the hissing sound will often intensify, which can be a tell if you’re looking for a 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 quickly if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be located in the exterior air conditioning unit, which is also called a condenser unit. Listen around here for the hissing noise. If you find the compressor is the cause, this could be an unsafe situation because it is a sign that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner pronto and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey units to repair or replace inside an AC unit. Compressors are the part responsible for circulating refrigerant through the system. You cannot turn on an air conditioner and cool your home without a compressor. The expense varies based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, you would need to replace it with another two stage compressor. It’s not possible to upgrade or downgrade the compressor type - your unit has specific requirements for what parts are installed in order to operate safely. While it’s impossible to say how much a compressor replacement is because of the variable costs, the expense is often big enough to think about a replacement in older units. This is why it’s crucial 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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