Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be disregarded. Among the probable causes are leaky refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating from your ducts, then you may have leaking 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 further.

Does the hissing sound stop after a few seconds?

If you hear a hissing noise that stops after a few seconds, you may not have any issues. That could be refrigerant in your expansion valve, which is part and parcel 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 along with a hissing sound? This may indicate a refrigerant leak. If a refrigerant leak develops, you may notice a slight hissing sound as the refrigerant escapes via the leak. The coolant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, shut down your HVAC and call a qualified HVAC company to come take a look.

If the issue is a valve leak, it should be repaired by a qualified technician as soon as possible. The job of the valves is to help with 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 sign if you’re looking for a cause. You must maintain proper pressure in your system for it operate correctly, and refrigerant leaks cause additional health and maintenance problems. It’s best 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 known as a condenser unit. Listen around here for the hissing noise. If it turns out that the compressor is the cause, this could be an unsafe situation because it is a signal that the pressure inside 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 expensive parts to repair or replace inside an air conditioner. Compressors are the part responsible for circulating refrigerant through the system. You cannot run an AC and cool your home without a compressor. The pricing changes 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 a two stage compressor. It’s impossible 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 say how much a compressor replacement is because of the variable costs, the bill is often big enough to consider a replacement in older ACs. 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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