Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be disregarded. 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 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 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 operation of your HVAC mechanicals.

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak develops, you may hear a light hissing sound as the refrigerant escapes from the leak. The coolant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, shut down your HVAC and call a professional HVAC company to come evaluate the noise.

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 sometimes grow louder, which can be a signal if you’re looking for a cause. You must maintain proper pressure in your system for it cool your home, and refrigerant leaks cause additional health and mechanical problems. You ought 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 known as a condenser. Listen nearby the condenser for the hissing noise. If you find the compressor is the issue, this could be a hazardous situation because it is a signal that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner immediately and call a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive units to repair or replace inside an AC unit. Compressors are the part responsible for pushing refrigerant through the system. You cannot power on an HVAC system and cool your home sans compressor. The expense changes 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 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 and won’t accept substitutes. While it’s impossible to give a quote online because of the variable costs, the receipt 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 trustworthy HVAC company if you hear hissing sounds coming from the compressor.


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