Why is my AC making a hissing noise?
A hissing noise coming from your HVAC system should not be disregarded. Among the possible causes are leaky 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 leaky air ducts. This is annoying, but not necessarily something to panic over. A hissing sound may be a sign for any of these things, but we’ll try to narrow it down a little more.
Does the hissing sound stop after a few seconds?
If you hear a hissing noise that stops after a few moments, you may not have any issues. That can be refrigerant in your expansion valve, which is part and parcel 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 is present, you may hear a slight hissing sound as the refrigerant escapes via the leak. The coolant escapes as a gas and can be a serious health concern. If you notice signs of a refrigerant leak, turn off your HVAC and call a expert HVAC company to come take a look.
If the issue is a valve leak, it should be repaired by a technician as soon as possible. The job of the valves is to help with the pressurization of the refrigerant gas and left alone, the leak will worsen. When it does, the hissing sound will increase, which can be a signal 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 maintenance problems. You ought to get this fixed post haste if possible.
Are Hissing Noises Coming from the Compressor?
The compressor can be located in the exterior air conditioning unit, which is also known as a condenser unit. Listen quietly for the hissing noise. If the compressor is the cause, this could be an unsafe situation because it is a sign that the pressure inside 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 a professional technician.

Compressors are some of the most pricey units to repair or replace inside an AC unit. Compressors are the part responsible for pushing refrigerant through the system. You cannot run an AC and cool your home sans compressor. The expense 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 impossible 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 receipt is often large enough to just do a replacement in older ACs. This is why it’s so important to shut off the air conditioning and call a reputable HVAC company if you hear hissing sounds coming from the compressor.