Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be overlooked. Among the potential causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating from your air ducts, then you may have leaking air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound may indicate 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 can be refrigerant in your expansion valve, which is part and parcel of the normal 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 could indicate a refrigerant leak. If a refrigerant leak presents itself, you may hear a light hissing sound as the refrigerant escapes via the leak. Refrigerant escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, shut down your HVAC and call a qualified 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 help with the pressurization of the refrigerant gas and left alone, the leak will worsen. When it does, the hissing sound will increase, which can be a sign if you’re looking for a cause. You need to maintain adequate pressure in your system for it operate correctly, and refrigerant leaks cause additional health and mechanical problems. You want to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be 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 problem, 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, power down your air conditioner without delay and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive parts to repair or replace inside an AC. Compressors are the part responsible for cycling refrigerant through the system. You cannot turn on an air conditioner and cool your home without a compressor. The cost varies based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor in your AC, you will need to replace it with a 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 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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