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 heard from your air ducts, then you could have leaking air ducts. This is annoying, but not necessarily a reason to worry. A hissing sound may indicate any of these things, but we’ll try to narrow it down 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 problems. That might 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 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 via the leak. The coolant escapes as a gas and can be a major health concern. If you see signs of a refrigerant leak, shut down the AC and call a expert HVAC company to come evaluate the noise.

If the cause is a valve leak, it should be repaired by a technician as soon as possible. The job of the valves is to manage the pressurization of the refrigerant gas and left alone, the leak will worsen. When it does, the hissing sound will often intensify, which can be a sign if you’re looking for a cause. You must maintain proper pressure in your HVAC 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 can be found in the outdoor air conditioning unit, which is also known as a condenser. Listen quietly for the hissing noise. If it turns out that the compressor is the cause, this could be a dangerous situation because it is an indication that the pressure within the compressor is too high. If you hear hissing, whistling, or shrieking coming from your compressor, shut off your air conditioner without delay 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 AC. 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 pricing changes based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor in the unit today, you would need to replace it with another 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 receipt is frequently big enough to consider a replacement in older air conditioners. This is why it’s critical to shut off the air conditioning and call a trustworthy HVAC company if you hear hissing sounds coming from the compressor.

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