Why is my AC making a hissing noise?

July 25, 2019

A hissing noise inside your HVAC system is not something to be overlooked. Among the potential causes are leaking5 refrigerant lines, an internal valve leak or a serious failure with your compressor. If the hissing noise is originating from your ductwork, then you could have leaky air ducts. This is annoying, but not necessarily a cause for alarm. 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 stops after a few seconds, you may not have any issues. That can be refrigerant in your expansion valve, which is part and parcel of the normal operation of your HVAC unit.

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 might hear a light 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, power down the unit and call a expert HVAC company to come inspect the system.

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 regulate the pressurization of the refrigerant gas and if unresolved, 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 proper pressure in your system for it operate correctly, and refrigerant leaks cause additional health and maintenance 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 called a condenser unit. Listen around here for the hissing noise. If it turns out that the compressor is the issue, this could be an unsafe situation because it is an indication 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 a professional technician.

AC compressor located in exterior condenser unit 

Compressors are some of the most expensive parts to repair or replace inside an AC. Compressors are the part responsible for cycling refrigerant through the system. You cannot turn on an air conditioner and cool your home sans compressor. The cost is variable based on factors such as the type, unit size, and brand requirements. If you have a two stage compressor now, you would need to replace it with another two stage compressor. It’s not possible to upgrade or downgrade the compressor type - your unit has specific requirements for what parts are installed and can’t be MacGyvered. While it’s impossible to give a quote online because of the variable costs, the expense is frequently big 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.

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