Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be disregarded. Among the possible causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is coming from your ductwork, then you might have leaking air ducts. This is annoying, but not necessarily something to panic over. A hissing sound could indicate any of these things, but we’ll try to narrow it down a little more.

Does the hissing sound cease 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 a part 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 is present, you might hear a slight hissing sound as the refrigerant escapes from the leak. It escapes as a gas and can be a worrisome health concern. If you notice signs of a refrigerant leak, power down the unit and call a qualified HVAC company to come inspect the system.

If the issue is a valve leak, it should be repaired by a technician as soon as possible. The job of the valves is to help with the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a sign if you’re looking for the cause. You must maintain proper pressure in your HVAC system for it cool your home, and leaks create additional health and mechanical problems. You want 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 within the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner pronto and call a professional 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 cycling refrigerant through the system. You cannot power on an HVAC system 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 will 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 components are installed in order to operate safely. While it’s impossible to give a quote online because of the variable costs, the expense is often high enough to just do a replacement in older units. 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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