Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be overlooked. 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 a cause for alarm. A hissing sound could be a sign for any of these things, but we’ll try to narrow it down further.

Does the hissing sound cease after a few seconds?

If you hear a hissing noise that ends after a few moments, you may not have any problems. That might be refrigerant in your expansion valve, which is part of the normal 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 may indicate a refrigerant leak. If a refrigerant leak presents itself, you might notice a light hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, turn off the AC and call a qualified HVAC company to come take a look.

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 help with the pressurization of the refrigerant gas and without repair, the leak will worsen. When it does, the hissing sound will increase, which can be a tell if you’re looking for a cause. You need to maintain proper pressure in your system for it cool your home, and any leak will create additional health and mechanical problems. You ought to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be found in the exterior air conditioning unit, which is also called a condenser. Listen quietly for the hissing noise. If you find the compressor is the problem, this could be a hazardous situation because it is a signal that the pressure within the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner immediately and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey parts to repair or replace inside an AC unit. Compressors are the part responsible for cycling refrigerant through the system. You cannot run an AC and cool your home without a compressor. The expense changes based on factors like 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 compressors are installed and can’t be MacGyvered. While it’s impossible to give a quote online because of the variable costs, the expense is often high enough to consider a replacement in older air conditioners. 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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