Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system should not be overlooked. Among the possible 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 leaky air ducts. This is annoying, but not necessarily something to panic over. A hissing sound could indicate 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 moments, you may not have any issues. That might be refrigerant in your expansion valve, which is part of the normal 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 may indicate a refrigerant leak. If a refrigerant leak is present, you may hear a slight hissing sound as the refrigerant escapes via the leak. Refrigerant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, power down 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 qualified technician 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 must maintain adequate pressure in your system for it run as intended, and any leak will create additional health and maintenance problems. You want 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. Listen around here for the hissing noise. If the compressor is the issue, this could be a dangerous situation because it is a sign that the pressure in the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, turn off your air conditioner without delay 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 air conditioner. Compressors are the part responsible for cycling refrigerant through the system. You cannot power on an HVAC system and cool your home sans compressor. The expense is variable based on factors such as 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 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 frequently large enough to think about a replacement in older ACs. This is why it’s critical 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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