Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be disregarded. Among the potential causes are leaking5 refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is originating from your air ducts, then you might have leaky air ducts. This is annoying, but not necessarily something to panic over. 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 ceases after a few moments, 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 mechanicals.

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 presents itself, you might notice a light hissing sound as the refrigerant escapes via the leak. It escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, shut down the unit and call a professional HVAC company to come inspect the system.

If the issue is a valve leak, it should be repaired by a professional 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 signal if you’re looking for the cause. You must maintain adequate pressure in your HVAC system for it operate correctly, and refrigerant leaks cause additional health and maintenance problems. It’s best to get this fixed quickly if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is found 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 a dangerous 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, turn off your air conditioner pronto and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey parts to repair or replace inside an AC. Compressors are the part responsible for pushing refrigerant through the system. You cannot turn on an air conditioner and cool your home without a compressor. The pricing is variable 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 impossible 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 provide estimates because of the variable costs, the bill is frequently high enough to just do a replacement in older units. This is why it’s so important 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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