Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be overlooked. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is coming from your ductwork, then you may have leaking air ducts. This is annoying, but not necessarily a reason to worry. 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 seconds, you may not have any issues. That might be refrigerant in your expansion valve, which is part of the normal operation of your HVAC mechanicals.

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 hear a slight hissing sound as the refrigerant escapes from the leak. Refrigerant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, power down the unit and call a qualified HVAC company to come take a look.

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 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 sign if you’re looking for the cause. You must maintain proper pressure in your HVAC system for it cool your home, and refrigerant leaks cause additional health and maintenance problems. You want to get this fixed quickly 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 unit. Listen around here for the hissing noise. If it turns out that the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure within the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner pronto and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey units 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 sans compressor. The pricing varies based on factors like the type, unit size, and brand requirements. If you have a two stage compressor now, 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 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 bill is often large enough to consider a replacement in older units. This is why it’s crucial 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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