Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be ignored. Among the potential causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is coming from your ducts, then you may have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down a little more.

Does the hissing sound end after a few seconds?

If you hear a hissing noise that ceases after a few seconds, you may not have any problems. That could be refrigerant in your expansion valve, which is 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 along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak develops, you may notice a light hissing sound as the refrigerant escapes from the leak. Refrigerant escapes as a gas and can be a worrisome health concern. If you notice signs of a refrigerant leak, power down the AC and call a professional HVAC company to come evaluate the noise.

If the problem is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to manage the pressurization of the refrigerant gas and left alone, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a sign if you’re looking for a cause. You need to maintain adequate pressure in your HVAC system for it cool your home, and refrigerant leaks cause additional health and maintenance problems. It’s best to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be found in the outdoor air conditioning unit, which is also known as a condenser. Listen nearby the condenser for the hissing noise. If the compressor is the cause, this could be an unsafe situation because it is a signal that the pressure within the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner without delay 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 AC. Compressors are the part responsible for pushing refrigerant through the system. You cannot run an AC and cool your home sans compressor. The cost varies 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 parts are installed and won’t accept substitutes. While it’s impossible to provide estimates because of the variable costs, the expense is frequently big enough to consider a replacement in older air conditioners. This is why it’s so important 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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