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 probable causes are leaky refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is coming from your ducts, then you may have leaking air ducts. This is annoying, but not necessarily a cause for alarm. 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 moments, you may not have any issues. That might 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 paired with a hissing sound? This could indicate a refrigerant leak. If a refrigerant leak is present, you might notice a slight hissing sound as the refrigerant escapes from the leak. Refrigerant escapes as a gas and can be a serious health concern. If you see signs of a refrigerant leak, turn off your HVAC and call a expert HVAC company to come inspect the system.

If the cause 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 if unresolved, the leak will worsen. When it does, the hissing sound will increase, which can be a signal if you’re looking for the cause. You need to maintain proper 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 can be found in the exterior air conditioning unit, which is also called a condenser. Listen around here for the hissing noise. If it turns out that the compressor is the problem, this could be an unsafe situation because it is a signal that the pressure in the compressor is too great. 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 units to repair or replace inside an AC unit. Compressors are the part responsible for pushing refrigerant through the system. You cannot power on an HVAC system and cool your home sans compressor. The cost varies based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in your AC, 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 and won’t accept substitutes. While it’s impossible to give a quote online because of the variable costs, the receipt is frequently big enough to consider 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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