Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system should not be overlooked. 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 could 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 a little further.

Does the hissing sound cease after a few seconds?

If you hear a hissing noise that ceases after a few seconds, 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 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 presents itself, you may hear a slight hissing sound as the refrigerant escapes from the leak. Refrigerant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, power down your HVAC and call a professional HVAC company to come inspect the system.

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 manage the pressurization of the refrigerant gas and without repair, the leak will worsen. When it does, the hissing sound will often intensify, which can be a signal 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 maintenance problems. You ought 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 called a condenser. Listen nearby the condenser for the hissing noise. If you find the compressor is the problem, this could be an unsafe situation because it is a signal that the pressure in the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner without delay and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly units to repair or replace inside an AC unit. 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 like the type, unit size, and brand requirements. If you have a two stage compressor in your AC, you would 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 can’t be MacGyvered. While it’s impossible to give a quote online because of the variable costs, the receipt is often large enough to just do a replacement in older air conditioners. This is why it’s crucial 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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