Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be disregarded. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is coming from your ductwork, then you could have leaky air ducts. This is annoying, but not necessarily a reason to worry. A hissing sound may 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 moments, you may not have any issues. That can be refrigerant in your expansion valve, which is a 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 along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak is present, you might notice a slight hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a worrisome health concern. If you see signs of a refrigerant leak, turn off the unit and call a professional HVAC company to come take a look.

If the problem is a valve leak, it should be repaired by a professional as soon as possible. The job of the valves is to help with 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 a cause. You need to maintain proper pressure in your HVAC system for it run as intended, and leaks create additional health and mechanical problems. You want 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 called a condenser unit. Listen around here for the hissing noise. If the compressor is the issue, this could be a hazardous 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 immediately and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey parts 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 without a compressor. The expense changes based on factors such as 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 and won’t accept substitutes. While it’s impossible to give a quote online because of the variable costs, the expense is frequently high enough to think about a replacement in older ACs. This is why it’s so important to shut off the air conditioning and call a reputable HVAC company if you hear hissing sounds coming from the compressor.

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