Why is my AC making a hissing noise?

July 25, 2019

A hissing noise coming from your HVAC system is not something to be disregarded. Among the probable causes are leaky refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is originating from your ductwork, then you may have leaky air ducts. This is annoying, but not necessarily a cause for alarm. A hissing sound could indicate any of these things, but we’ll try to narrow it down a little further.

Does the hissing sound end after a few seconds?

If you hear a hissing noise that stops after a few moments, you may not have any problems. That can be refrigerant in your expansion valve, which is a 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 can indicate a refrigerant leak. If a refrigerant leak develops, you might notice a slight hissing sound as the refrigerant escapes through the leak. Refrigerant escapes as a gas and can be a major health concern. If you have signs of a refrigerant leak, power down your HVAC and call a professional 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 regulate the pressurization of the refrigerant gas and if unresolved, 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 adequate pressure in your system for it operate correctly, and refrigerant leaks cause additional health and mechanical problems. You want 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 called a condenser. Listen quietly for the hissing noise. If the compressor is the problem, this could be a hazardous situation because it is a signal that the pressure inside the compressor is too much. If you hear hissing, whistling, or shrieking coming from your compressor, switch off your air conditioner immediately and call an expert technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most costly parts to repair or replace inside an air conditioner. Compressors are the part responsible for pushing refrigerant through the system. You cannot power on an HVAC system and cool your home without a compressor. The cost is variable based on factors like the type, unit size, and brand requirements. If you have a two stage compressor now, 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 components are installed in order to operate safely. While it’s impossible to provide estimates because of the variable costs, the expense is frequently big enough to consider a replacement in older units. This is why it’s so important to shut off the air conditioning and call a reliable HVAC company if you hear hissing sounds coming from the compressor.

Contact Us