Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be ignored. Among the probable causes are leaking5 refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is originating from your ductwork, then you may 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 develops, you may notice a light hissing sound as the refrigerant escapes via 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 expert HVAC company to come inspect the system.

If the cause is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to manage 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 cool your home, and any leak will create 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 called a condenser unit. Listen quietly for the hissing noise. If it turns out that the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure in the compressor is too much. 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 expensive parts to repair or replace inside an AC unit. Compressors are the part responsible for cycling refrigerant through the system. You cannot run an AC and cool your home sans compressor. The expense changes based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, 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 compressors are installed in order to operate safely. While it’s impossible to say how much a compressor replacement is because of the variable costs, the expense is frequently high enough to consider 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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