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 issue with your compressor. If the hissing noise is heard from your ductwork, then you might have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound could indicate any of these things, but we’ll try to narrow it down a little more.

Does the hissing sound cease after a few seconds?

If you hear a hissing noise that stops 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 system.

Is the AC Making a Hissing Sound with Bubbling Noises?

Are you hearing a bubbling sound paired with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak is present, you may hear a slight hissing sound as the refrigerant escapes through the leak. It escapes as a gas and can be a serious health concern. If you see signs of a refrigerant leak, turn off the AC and call a expert HVAC company to come evaluate the noise.

If the cause 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 increase, which can be a tell if you’re looking for the cause. You need to maintain proper pressure in your system for it cool your home, and refrigerant leaks cause additional health and maintenance problems. You want to get this fixed post haste 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 unit. Listen around here for the hissing noise. If it turns out that the compressor is the issue, this could be a dangerous situation because it is an indication that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner pronto 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 circulating refrigerant through the system. You cannot run an AC and cool your home sans compressor. The pricing varies 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 a two stage compressor. It’s not possible 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 give a quote online because of the variable costs, the expense is often large enough to think about a replacement in older air conditioners. This is why it’s critical 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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