Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be disregarded. Among the potential causes are leaking5 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 a cause for alarm. 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 stops after a few seconds, you may not have any problems. That can 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 might notice a light hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, turn off your HVAC and call a expert HVAC company to come inspect the system.

If the problem is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to regulate the pressurization of the refrigerant gas and if unresolved, the leak will worsen. When it does, the hissing sound will often intensify, which can be a tell if you’re looking for the cause. You must maintain adequate pressure in your HVAC system for it cool your home, and refrigerant leaks cause additional health and mechanical problems. It’s best to get this fixed post haste if possible.

Are Hissing Noises Coming from the Compressor?

The compressor is located in the outdoor air conditioning unit, which is also called a condenser. Listen around here for the hissing noise. If you find the compressor is the issue, this could be an unsafe situation because it is a sign that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, shut off your air conditioner immediately and call an HVAC technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most pricey parts to repair or replace inside an air conditioner. Compressors are the part responsible for pushing refrigerant through the system. You cannot run an AC and cool your home sans compressor. The pricing is variable based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, 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 won’t accept substitutes. While it’s impossible to provide estimates because of the variable costs, the expense is often big enough to think about a replacement in older units. 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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