Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be disregarded. Among the potential causes are leaky refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating 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 further.

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 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 from the leak. The coolant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, shut down the AC and call a qualified HVAC company to come take a look.

If the issue 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 left alone, the leak will worsen. When it does, the hissing sound will sometimes grow louder, which can be a tell if you’re looking for a cause. You must maintain adequate pressure in your system for it run as intended, 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 unit. Listen nearby the condenser for the hissing noise. If the compressor is the problem, this could be an unsafe situation because it is a sign that the pressure inside the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner immediately and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly parts 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 without a compressor. The pricing is variable based on factors such as 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 a 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 give a quote online because of the variable costs, the bill is frequently large enough to just do a replacement in older ACs. This is why it’s crucial to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.

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