Why is my AC making a hissing noise? 

A hissing noise inside your HVAC system is not something to be ignored. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is heard from your ductwork, then you may have leaking 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 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 issues. That might be refrigerant in your expansion valve, which is a part of the normal operation of your HVAC unit. 

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 might hear a light hissing sound as the refrigerant escapes through the leak. It escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, turn off the AC and call a professional HVAC company to come inspect the system. 

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 help with the pressurization of the refrigerant gas and without repair, 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 must maintain proper pressure in your system for it operate correctly, and refrigerant leaks cause additional health and mechanical problems. You ought to get this fixed quickly if possible. 

Are Hissing Noises Coming from the Compressor? 

The compressor is found in the exterior air conditioning unit, which is also called a condenser. 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 a signal that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, shut off your air conditioner pronto and call an HVAC technician. 

Photo of AC unit showing location of compressor

Compressors are some of the most expensive units to repair or replace inside an AC. Compressors are the part responsible for pushing refrigerant through the system. You cannot power on an HVAC system and cool your home sans compressor. The expense varies based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, you would 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 receipt is frequently high enough to just do a replacement in older ACs. This is why it’s critical 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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