Why is my AC making a hissing noise? 

A hissing noise inside your HVAC system should not be overlooked. Among the probable causes are leaking refrigerant lines, an internal valve leak or a serious issue with your compressor. If the hissing noise is coming from your air ducts, then you might 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 a little more. 

Does the hissing sound cease after a few seconds? 

If you hear a hissing noise that ends after a few moments, you may not have any issues. That could be refrigerant in your expansion valve, which is a 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 paired with a hissing sound? This can indicate a refrigerant leak. If a refrigerant leak is present, you might hear a slight hissing sound as the refrigerant escapes through the leak. The coolant escapes as a gas and can be a major health concern. If you notice signs of a refrigerant leak, turn off the unit and call a qualified HVAC company to come evaluate the noise. 

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 regulate the pressurization of the refrigerant gas and without repair, 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 need to maintain adequate pressure in your system for it operate correctly, 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 unit. Listen nearby the condenser for the hissing noise. If you find the compressor is the cause, this could be an unsafe situation because it is a signal that the pressure within the compressor is too great. If you hear hissing, whistling, or shrieking coming from your compressor, power down your air conditioner immediately and call a professional technician. 

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 turn on an air conditioner and cool your home without a compressor. The cost is variable based on factors such as 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 another two stage compressor. It’s impossible to upgrade or downgrade the compressor type – your unit has specific requirements for what components are installed and can’t be MacGyvered. While it’s impossible to provide estimates because of the variable costs, the bill is often large enough to think about a replacement in older air conditioners. 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.