Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be ignored. Among the possible causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is coming from your ductwork, then you may have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound may indicate any of these things, but we’ll try to narrow it down further.

Does the hissing sound end 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 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 paired with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak is present, you may hear a slight hissing sound as the refrigerant escapes via the leak. It escapes as a gas and can be a major health concern. If you notice signs of a refrigerant leak, turn off the AC and call a expert HVAC company to come inspect the system.

If the problem is a valve leak, it should be repaired by a technician 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 increase, which can be a sign 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 post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is located in the exterior air conditioning unit, which is also called a condenser unit. Listen quietly for the hissing noise. If you find the compressor is the issue, this could be an unsafe situation because it is a signal that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner pronto 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 pushing refrigerant through the system. You cannot run an AC and cool your home without a compressor. The pricing varies based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in your AC, you will 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 give a quote online because of the variable costs, the receipt is often large enough to just do a replacement in older units. 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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