Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be ignored. Among the possible causes are leaking5 refrigerant lines, an internal valve leak or a serious problem with your compressor. If the hissing noise is originating from your ducts, then you could have leaking air ducts. This is annoying, but not necessarily something to panic over. A hissing sound may indicate 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 ends after a few moments, you may not have any problems. That could be refrigerant in your expansion valve, which is 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 along with a hissing sound? This can indicate a refrigerant leak. If a refrigerant leak develops, you might hear a slight hissing sound as the refrigerant escapes from the leak. It escapes as a gas and can be a major health concern. If you notice signs of a refrigerant leak, power down 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 without repair, the leak will worsen. When it does, the hissing sound will increase, which can be a tell if you’re looking for a cause. You need to maintain adequate pressure in your HVAC system for it cool your home, and any leak will create 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 outdoor air conditioning unit, which is also known as a condenser. Listen around here for the hissing noise. If the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure inside the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner pronto and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive units 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 expense varies based on factors like the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you will 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 in order to operate safely. While it’s impossible to give a quote online because of the variable costs, the bill is frequently large enough to just do a replacement in older ACs. This is why it’s critical to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.

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