Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be overlooked. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is heard from your air ducts, then you could have leaky air ducts. This is annoying, but not necessarily something to panic over. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down a little more.

Does the hissing sound stop after a few seconds?

If you hear a hissing noise that stops after a few moments, you may not have any problems. 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 presents itself, you might hear a slight hissing sound as the refrigerant escapes via the leak. The coolant escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, power down 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 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 sometimes grow louder, which can be a sign if you’re looking for the cause. You must maintain adequate pressure in your system for it operate correctly, and refrigerant leaks cause additional health and maintenance problems. You want to get this fixed quickly if possible.

Are Hissing Noises Coming from the Compressor?

The compressor can be located in the outdoor air conditioning unit, which is also known as a condenser. Listen around here for the hissing noise. If you find the compressor is the issue, this could be a dangerous situation because it is a signal that the pressure inside the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner without delay and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive units to repair or replace inside an AC. Compressors are the part responsible for cycling refrigerant through the system. You cannot run an AC and cool your home sans compressor. The pricing changes based on factors like 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 parts 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 bill is frequently large enough to consider a replacement in older air conditioners. This is why it’s so important 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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